Method and system for intake air filter diagnosis

Abstract

The present disclosure provides "Methods and systems for intake air filter diagnosis". Methods and systems are provided for diagnosing an intake air filter during a vehicle off condition. In one example, an engine can be caused to reverse rotate without fueling and air flow through an exhaust manifold and an intake manifold is estimated and compared to a baseline air flow. A clogged intake air flow can be indicated based on the comparison between air flow through the exhaust manifold and the intake manifold and the baseline air flow after an auxiliary flow path to atmosphere is opened.

Description

TECHNICAL FIELD

[0001] The present description generally relates to methods and systems for diagnosing an intake air filter during a vehicle off condition. BACKGROUND

[0002] An air filter positioned within or as part of an intake system of an engine provides filtered air to the engine. The air filter can extract dust, dirt, and other airborne material from the air intake system of the engine so that the airborne material does not accumulate in the engine and degrade engine performance and operation. However, the airborne material can accumulate within the air filter over time so that the air filter can restrict the flow of air into the engine. The restriction of air flow caused by the air filter can increase the engine pumping work and decrease vehicle fuel economy. To replace or clean a clogged air filter, the status of the air filter can be diagnosed periodically and indicated to an operator.

[0003] Various methods for performing a diagnosis of an intake air filter are provided. In one exemplary method, shown in U.S. Patent Application Publication No. 20110185895 to Freen et al., a diagnostic method for an intake air filter is shown using a pressure sensing module that includes a battery-powered pressure sensing probe coupled across an intake air filter. The pressure sensing probe measures a pressure differential between a first location upstream of the air filter and a second location downstream of the air filter. The filter condition is then determined by comparing the pressure differential to a predetermined baseline pressure differential.

[0004] However, the inventors herein have recognized potential drawbacks of the above method. As one example, in the system described by Freen, a battery-powered probe is used to measure a pressure differential across an air filter that is generally not present around an air filter in a naturally aspirated engine. The additional probe can add complexity and cost to the engine system. Also, the operation of a sensor operated off of a battery can increase parasitic losses of engine power due to the energy required to recharge the battery. Furthermore, because the user will perform a recalibration of the baseline pressure differential each time a new filter is installed, the described method can result in an incorrect estimation of the filter condition if the recalibration is not performed in a timely manner. The air filter diagnosis relies on the engine being operated and intake flow into the engine. However, in a hybrid vehicle, the engine can be operated for a short duration. Thus, the air filter diagnosis can not be performed on a regular basis, resulting in the vehicle being operated for long periods of time with a clogged or blocked air filter. SUMMARY

[0005] The inventors herein have recognized that the problems described above can be addressed by an engine method that includes indicating a clogged intake air filter based on an air flow through an exhaust system relative to an air flow through an intake system and further based on a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere during a run-on of the engine without fuel when the engine is turned in a reverse direction. In this way, by timely turning the engine in a reverse direction during a vehicle off condition and monitoring the air flow through the exhaust manifold and intake manifold, a clogged intake air filter can be diagnosed.

[0006] As one example, a diagnostic routine for an intake air filter can be timely implemented during a vehicle off condition when the engine is not in operation and the vehicle is unoccupied. The diagnostic routine includes rotating the engine in a reverse direction via an electric motor and also turning a battery-operated electric supercharger coupled to an intake manifold in a reverse direction to draw ambient air from an exhaust tailpipe and deliver the air to the intake manifold. An air flow through the exhaust passage is estimated via a differential pressure sensor coupled across a particulate filter, and an air flow through the intake passage is estimated via a manifold air flow (MAF) sensor. The exhaust air flow and the intake air flow can be compared to each other and then further compared to a baseline air flow. The baseline air flow can be obtained after installing an intake air filter by reversing the engine and estimating the air flow through the intake manifold via the MAF sensor. If the intake air flow is determined to be substantially equal to each of the exhaust air flow and the baseline air flow, then the intake air filter can be indicated as not being clogged. If the exhaust air flow is determined to be substantially equal to the intake air flow but lower than the baseline air flow, then a canister purge valve (CPV) and a canister vent valve (CVV) coupled to a canister purge line of an evaporative emission control (EVAP) system can be opened to enable an alternative route for fluid communication between the engine system and atmosphere. After opening the CPV and CVV, air entering through the exhaust manifold can be released to atmosphere through the canister purge line without flowing through the portion of the intake passage that houses the MAF sensor and the intake air filter. Thus, if an increase in the exhaust air flow to the baseline air flow is observed without a significant change in the intake air flow, then it can be inferred that the intake air filter is clogged and a diagnostic code can be set.

[0007] In this way, the diagnosis of the intake air filter can be performed in a timely manner using components that are already present in the engine system, thereby providing a cost benefit. The technical effect of detecting clogging in the intake air filter is that the desired air-fuel ratio can be maintained and the combustion of rich stoichiometric air-fuel blends can be reduced. By maintaining the desired air-fuel ratio, the fouling of the spark plug can be reduced and the desired timing of the ignition can be maintained. Overall, by periodically monitoring the health of the intake air filter, degradation of the air filter can be detected in a timely manner, and replacement of a clogged intake air filter can result in increased vehicle fuel economy and emissions quality.

[0008] It is understood that the above summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter to any implementation described in this summary. Furthermore, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages described above or in any part of this disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 An exemplary hybrid vehicle propulsion system is schematically illustrated.

[0010] Figure 2 An exemplary vehicle system with an electric supercharger is schematically illustrated.

[0011] Figure 3 A block diagram schematically illustrating an exemplary autonomous driving system is illustrated.

[0012] Figure 4A And Figure 4B An exemplary H-bridge circuit that can be used to rotate a vehicle engine in either a forward or reverse direction is schematically illustrated.

[0013] Figure 5 A flowchart illustrating an exemplary method that can be implemented to diagnose degradation of an exhaust tuning valve is illustrated.

[0014] Figure 6 Exemplary operation of an engine and electric supercharger for exhaust tuning valve diagnosis in accordance with the present disclosure is illustrated.

[0015] Figure 7A And Figure 7B A flowchart illustrating an exemplary method for diagnosing degradation of an intake air filter is illustrated.

[0016] Figure 8 Exemplary operation of an engine and electric supercharger for intake air filter diagnosis in accordance with the present disclosure is illustrated. DETAILED DESCRIPTION

[0017] The following description relates to systems and methods for diagnosing exhaust tuning valves and intake air filters during vehicle shutdown conditions. Such methods may include turning or rotating the engine without fuel injection, wherein the engine is connected via a hybrid vehicle (e.g., in a...). Figure 1 The electric motor in the hybrid vehicle (described here) is used to run the engine even when no fuel is being added. Figure 2 The diagram illustrates an exhaust tuning valve for regulating exhaust noise and an intake air filter for cleaning ambient air entering the engine intake manifold. In some examples, a set of predetermined conditions for performing diagnostics on one or more of the exhaust tuning valve and the intake air filter may include an indication that the vehicle is not occupied. Therefore, in some examples, such measurements can be performed in an autonomous vehicle that is not occupied, where... Figure 3 An exemplary autonomous vehicle control system is depicted. To enable the engine to rotate in both forward and reverse directions without fuel, an H-bridge circuit can be utilized, for example in… Figures 4A-4B The H-bridge circuit is depicted here. The engine controller can be configured to execute control routines, such as... Figure 5 Exemplary routines are provided to diagnose deterioration of the exhaust tuning valve. The engine controller can execute... Figures 7A-7B An exemplary routine is provided to detect a clogged intake air filter. Figure 6 and Figure 8 The diagrams show exemplary electric supercharger operation and engine operation for implementing exhaust tuning valve diagnostics and intake air filter diagnostics, respectively.

[0018] Figure 1 An exemplary vehicle propulsion system 100 is described. The vehicle propulsion system 100 includes a fuel-burning engine 110 and a motor 120. As a non-limiting example, the engine 110 includes an internal combustion engine and the motor 120 includes an electric motor. The motor 120 can be configured to utilize or consume energy sources different from those of the engine 110. For example, the engine 110 may consume liquid fuel (e.g., gasoline) to produce engine output, while the motor 120 may consume electrical energy to produce motor output. Therefore, a vehicle having the propulsion system 100 can be referred to as a hybrid electric vehicle (HEV).

[0019] The vehicle propulsion system 100 can utilize various operating modes depending on the operating conditions encountered by the vehicle propulsion system. Some of these modes allow the engine 110 to remain in a shut-off state (i.e., set to a deactivated state), in which combustion of fuel at the engine is stopped. For example, under selected operating conditions, when the engine 110 is deactivated, the motor 120 can propel the vehicle via the drive wheels 130, as indicated by arrow 122.

[0020] During other operating conditions, the engine 110 can be set to an inactive state (as described above), while the motor 120 can be operated to charge the energy storage device 150. For example, the motor 120 can receive wheel torque from the drive wheels 130, as indicated by arrow 122, where the motor can convert the vehicle's kinetic energy into electrical energy for storage at the energy storage device 150, as indicated by arrow 124. This operation can be referred to as regenerative braking of the vehicle. Thus, in some examples, the motor 120 can provide a generator function. However, in other examples, a generator 160 can instead receive wheel torque from the drive wheels 130, where the generator can convert the vehicle's kinetic energy into electrical energy for storage at the energy storage device 150, as indicated by arrow 162.

[0021] During other operating conditions, the engine 110 can be operated by burning fuel received from the fuel system 140, as indicated by arrow 142. For example, when the motor 120 is inactive, the engine 110 can be operated to propel the vehicle via the drive wheels 130, as indicated by arrow 112. During other operating conditions, the engine 110 and the motor 120 can each be operated to propel the vehicle via the drive wheels 130, as indicated by arrows 112 and 122, respectively. The configuration in which the engine and motor can selectively propel the vehicle can be referred to as a parallel type vehicle propulsion system. It should be noted that, in some examples, the motor 120 can propel the vehicle via a first set of drive wheels, and the engine 110 can propel the vehicle via a second set of drive wheels.

[0022] In other examples, the vehicle propulsion system 100 can be configured as a series type vehicle propulsion system, whereby the engine does not directly propel the drive wheels. Rather, the engine 110 can be operated to supply power to the motor 120, which can in turn propel the vehicle via the drive wheels 130, as indicated by arrow 122. For example, during selected operating conditions, the engine 110 can drive the generator 160, as indicated by arrow 116, which can in turn supply electrical energy to one or more of the motors 120, as indicated by arrow 113, or to the energy storage device 150, as indicated by arrow 162. As another example, the engine 110 can be operated to drive the motor 120, which can in turn provide a generator function to convert the engine output into electrical energy, where the electrical energy can be stored at the energy storage device 150 for later use by the motor.

[0023] In other examples, to be discussed in detail below, in some examples the motor 120 can be utilized to rotate or spin the motor in an unfueled configuration. More specifically, the motor 120 can use electrical power from an on-board energy storage device 150, which can include, for example, a battery, to spin the engine without fuel. In cases where the motor 120 is used to spin the engine without fuel, fuel injection to the engine cylinders can be prevented, and a spark can not be provided to each of the engine cylinders.

[0024] The fuel system 140 can include one or more fuel storage tanks 144 for storing fuel on the vehicle. For example, the fuel tanks 144 can store one or more liquid fuels, including, but not limited to, gasoline, diesel, and ethanol fuels. In some examples, fuel can be stored on the vehicle as a blend of two or more different fuels. For example, the fuel tanks 144 can be configured to store a blend of gasoline and ethanol (e.g., E10, E85, etc.) or a blend of gasoline and methanol (e.g., M10, M85, etc.), whereby these fuels or fuel blends can be delivered to the engine 110 as indicated by the arrows 142. Other suitable fuels or fuel blends can be supplied to the engine 110, where they can be combusted at the engine to produce an engine output. The engine output can be utilized to propel the vehicle, as indicated by the arrows 112, or to recharge the energy storage device 150 via the motor 120 or generator 160.

[0025] In some examples, the energy storage device 150 can be configured to store electrical energy, which can be supplied to other electrical loads resident on the vehicle in addition to the motor, including cabin heating and air conditioning, engine starting, headlamps, cabin audio and video systems, etc. As non-limiting examples, the energy storage device 150 can include one or more batteries and / or capacitors.

[0026] The control system 190 can communicate with one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160. The control system 190 can receive sensory feedback information from one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160. In addition, the control system 190 can send control signals to one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160 in response to this sensory feedback. The control system 190 can receive an indication of an operator-requested output of the vehicle propulsion system from the vehicle operator 102. For example, the control system 190 can receive sensory feedback from a pedal position sensor 194 in communication with a pedal 192. The pedal 192 can illustratively be a brake pedal and / or an accelerator pedal. In addition, in some examples, the control system 190 can communicate with a remote engine start receiver 195 (or transceiver) that receives a wireless signal 106 from a key fob 104 having a remote start button 105. In other examples (not shown), a remote engine start can be initiated via a cellular phone or smart phone-based system, where the user's cellular phone sends data to a server and the server communicates with the vehicle to start the engine.

[0027] The vehicle system 100 can include a human-machine interface (HMI) 133 coupled to a vehicle dashboard via which an operator can communicate with the control system 190. The HMI 133 can include a touch-sensitive display screen. In one example, an operator can specify a desired level of engine exhaust noise via input to the HMI 133. The operator can also want to adjust the exhaust noise level based on the time of day. In one example, the operator can set the exhaust noise to a lower level during the morning hours and then change the noise level to a higher level during later hours of the day. In another example, the operator can want to maintain a constant exhaust noise level and can not frequently change the setting for the desired exhaust noise level. The position of the butterfly of the exhaust tuning valve can be adjusted based on the desired exhaust noise level to change the exhaust flow through the exhaust muffler. With respect to Figure 2 The exhaust system and the exhaust tuning valve are described together.

[0028] The energy storage device 150 can periodically receive electrical energy from a power source 180 that resides outside of the vehicle (e.g., is not part of the vehicle), as indicated by arrow 184. As a non-limiting example, the vehicle propulsion system 100 can be configured as a plug-in hybrid electric vehicle (HEV), whereby electrical energy can be supplied from the power source 180 to the energy storage device 150 via an electrical energy transfer cable 182. The electrical energy transfer cable 182 can electrically couple the energy storage device 150 and the power source 180 during a recharging operation of the energy storage device 150 from the power source 180. The electrical energy transfer cable 182 can be disconnected between the power source 180 and the energy storage device 150 when operating the vehicle propulsion system to propel the vehicle. The control system 190 can identify and / or control the amount of electrical energy stored at the energy storage device, which can be referred to as the state of charge (SOC).

[0029] In other examples, the electrical energy transfer cable 182 can be omitted, where electrical energy can be received wirelessly at the energy storage device 150 from the power source 180. For example, the energy storage device 150 can receive electrical energy from the power source 180 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Thus, it should be appreciated that any suitable method can be used for recharging the energy storage device 150 from a power source that does not form part of the vehicle. In this way, the motor 120 can propel the vehicle by utilizing an energy source other than fuel utilized by the engine 110.

[0030] The fuel system 140 can periodically receive fuel from a fuel source that resides outside of the vehicle. As a non-limiting example, the vehicle propulsion system 100 can be refueled by receiving fuel via a fuel dispensing device 170, as indicated by arrow 172. In some examples, the fuel tank 144 can be configured to store fuel received from the fuel dispensing device 170 until the fuel is supplied to the engine 110 for combustion. In some examples, the control system 190 can receive an indication of a level of fuel stored at the fuel tank 144 via a fuel level sensor. The level of fuel stored at the fuel tank 144 (e.g., identified by the fuel level sensor) can be communicated to a vehicle operator, for example, via a fuel gauge or indicator in a vehicle dashboard 196.

[0031] The vehicle propulsion system 100 can also include an ambient temperature / humidity sensor 198 and roll stability control sensors (e.g., lateral and / or longitudinal and / or yaw rate sensors 199). The vehicle instrument panel 196 can include indicator lights and / or a text-based display in which messages are displayed to the operator. The vehicle instrument panel 196 can also include various input portions for receiving operator input, such as buttons, touchscreens, voice input / recognition, etc. For example, the vehicle instrument panel 196 can include a refueling button 197 that can be manually actuated or pressed by the vehicle operator to initiate refueling. For example, as described in greater detail below, in response to the vehicle operator actuating the refueling button 197, the fuel tank in the vehicle can be depressurized so that refueling can be performed.

[0032] The control system 190 can be communicatively coupled to other vehicles or infrastructure using appropriate communication techniques that are well known in the art. For example, the control system 190 can be coupled to other vehicles or infrastructure via a wireless network 131, which can include Wi-Fi, Bluetooth, cellular service types, wireless data transfer protocols, etc. The control system 190 can broadcast (and receive) information about vehicle data, vehicle diagnostics, traffic conditions, vehicle location information, vehicle operating procedures, etc. via vehicle-to-vehicle (V2V), vehicle-to-infrastructure-to-vehicle (V2I2V), and / or vehicle-to-infrastructure (V2I) techniques. The communications and information exchanged between vehicles can be direct between vehicles or can be multi-hop. In some examples, longer range communications (e.g., WiMax) can be used instead of or in conjunction with V2V or V2I2V to extend the coverage area several miles. In other examples, the vehicle control system 190 can be communicatively coupled to other vehicles or infrastructure via wireless networks 131 and the Internet (e.g., the cloud) that are generally known in the art.

[0033] The vehicle system 100 can also include an on-board navigation system 132 (e.g., a global positioning system) that an operator of the vehicle can interact with. The navigation system 132 can include one or more position sensors for assisting in estimating vehicle speed, vehicle elevation, vehicle positioning / location, etc. This information can be used to infer engine operating parameters, such as local barometric pressure. As discussed above, the control system 190 can be further configured to receive information via the Internet or other communication networks. Information received from the GPS can be cross-referenced with information that can be obtained via the Internet to determine local weather conditions, local vehicle regulations, etc. In one example, information received from the GPS can be utilized in conjunction with a route learning method, such that the vehicle control system 190 can learn the routes that the vehicle typically travels. In some examples, other sensors, such as lasers, radar, sonar, acoustic sensors, etc. can additionally or alternatively be utilized in conjunction with the on-board navigation system to perform route learning of the routes that the vehicle typically travels.

[0034] The vehicle system 100 can also include sensors that are dedicated to indicating the occupancy status of the vehicle, such as seat load sensors 107, door sensing technology 108, and on-board cameras 109.

[0035] Figure 2 A schematic depiction 200 of a vehicle system 206 is shown. It can be appreciated that the vehicle system 206 can include the same vehicle system as the vehicle system 100 depicted at Figure 1 The vehicle system 206 includes an engine system 208 coupled to an emissions control system 251 and a fuel system 219. It can be appreciated that the fuel system 219 can include the same fuel system as the fuel system 140 depicted at Figure 1 The emissions control system 251 includes a fuel vapor container or canister 222 that can be used to capture and store fuel vapor. In some examples, the vehicle system 206 can be a hybrid electric vehicle system.

[0036] Engine system 208 may include engine 110 having a plurality of cylinders 230. Although not explicitly shown, it is understood that each cylinder may include one or more intake valves and one or more exhaust valves. Engine 110 includes engine intake port 223 and engine exhaust port 225. Engine intake port 223 includes throttle valve 262 in fluid communication with engine intake manifold 244 via intake passage 242. Throttle valve 262 may include an electronic throttle valve that can be controlled via a vehicle controller that sends a signal to actuate the throttle valve to a desired position. In such examples where the throttle valve is electronic, the power used to control the throttle valve to the desired position may come from an on-board energy storage device (e.g., 150), such as a battery. Furthermore, engine intake port 223 may include an air box and intake air filter 215 positioned upstream of throttle valve 262.

[0037] In the depicted embodiment, engine 110 is a turbocharged engine coupled to a turbocharger, which includes a compressor 114 driven by a turbine 116. Specifically, fresh air is introduced into engine 110 via an intake air filter 215 along an intake duct 242 and flows to compressor 114. The compressor can be any suitable intake compressor, such as a motor-driven or driveshaft-driven supercharger compressor. In engine system 110, the compressor is a turbocharger compressor mechanically coupled to turbine 116 via a shaft 19, turbine 116 being driven by expanding engine exhaust.

[0038] like Figure 2 As shown, compressor 114 is connected to throttle valve 262 via booster air cooler (CAC) 118. Compressed air charge flows from compressor through booster air cooler 118 and throttle valve 262 to intake manifold 244.

[0039] To assist the turbocharger, an electric supercharger 155 (eBooster) can be incorporated into the vehicle propulsion system. The electric supercharger 155 can be powered via an on-board energy storage device 250, which can include a battery, a capacitor, a super capacitor, etc. In one example, the electric supercharger 155 can be activated (actuated on) in response to a demand for wheel torque in order to quickly provide the desired boost air without delay if the turbocharger were utilized without the electric supercharger, which can otherwise occur. In this example, the electric supercharger 155 can be actuated off or deactivated in response to the turbocharger spinning up to a threshold speed (e.g., 70,000 rpm). More specifically, operation control of the electric supercharger 155 can be controlled by a vehicle controller (e.g., controller 12). For example, the controller can send a signal to an electric supercharger actuator 155b, which can actuate on the electric supercharger. In another example, the controller can send a signal to the electric supercharger actuator 155b, which can actuate off the electric supercharger. In one example, the electric supercharger actuator can include a motor that drives compression of air.

[0040] The electric supercharger 155 can be positioned between a first electric supercharger conduit 159a and a second electric supercharger conduit 159b. The first electric supercharger conduit 159a can fluidly couple the intake tract 42 to the electric supercharger 155 upstream of an electric supercharger bypass valve 161. The second electric supercharger conduit 159b can fluidly couple the electric supercharger 155 to the intake tract 42 downstream of the electric supercharger bypass valve 161. For example, air can be drawn into the electric supercharger 155 upstream of the electric supercharger bypass valve 161 via the first electric supercharger conduit 159a, and compressed air can exit the electric supercharger 155 and be carried to the intake tract 42 downstream of the electric supercharger bypass valve 161 via the second electric supercharger conduit. In this way, compressed air can be carried to the engine intake 244.

[0041] In situations where the electric supercharger 155 is activated to provide boost more quickly than if relying solely on the turbocharger, it can be appreciated that the electric supercharger bypass valve 161 can be commanded closed when the electric supercharger 155 is activated. In this way, intake air can flow through the turbocharger and the electric supercharger 155. Once the turbocharger reaches a threshold speed, the electric supercharger 155 can be closed, and the electric supercharger bypass valve 161 can be commanded open. In one example, when the engine is made to rotate in a reverse direction, the electric supercharger can also be made to rotate in a direction opposite the default rotation direction in order to create a flow of air from the exhaust tract to the engine cylinders 230.

[0042] The engine exhaust system 225 includes an exhaust manifold 248 leading to an exhaust passage 235 that carries exhaust gases to the atmosphere. The engine exhaust system 225 can include one or more exhaust catalysts 270 that can be mounted in close coupled locations in the exhaust. The one or more emission control devices can include a three-way catalyst, a lean NOx trap, a diesel particulate filter, an oxidation catalyst, etc. It will be appreciated that other components can be included in the engine, such as various valves and sensors. For example, a barometric pressure sensor 213 can be included in the engine intake. In one example, the barometric pressure sensor 213 can be a manifold air pressure (MAP) sensor and can be coupled to the engine intake downstream of a throttle valve 262. Alternatively, the MAP can be inferred from alternative engine operating conditions, such as mass air flow (MAF) measured by a MAF sensor 210 coupled to the intake manifold.

[0043] The engine exhaust system 225 can also include a gasoline particulate filter (GPF) 217. The GPF 217 can include a particulate filter, a hydrocarbon trap, a catalytic coating, or a combination thereof. In some examples, during operation of the engine 110, the GPF 217 can be periodically regenerated by operating at least one cylinder of the engine within a certain air-fuel ratio to increase the temperature of the GPF 217 such that retained hydrocarbon and soot particulates can be oxidized.

[0044] In some examples, a temperature sensor 226 can be positioned upstream of the inlet of the GPF 217 and a temperature sensor 229 can be positioned downstream of the GPF 217. The temperature sensors 226 and 229 can be used to assess the temperature of the GPF 217, for example, for the purpose of regeneration. Further, a pressure sensor 263 can assess the pressure in the exhaust system. For example, the pressure sensor 263 can be a differential pressure sensor positioned upstream and downstream of the GPF 217. The pressure sensor 263 can be used to determine the pressure at the inlet of the GPF 217 in order to assess the operating conditions of the air to be introduced to the inlet of the GPF 217 for regeneration. Further, in some examples, a soot sensor can be positioned downstream of the GPF 217 to assess the level of soot released from the GPF 217.

[0045] A muffler 220 is also positioned downstream of the GPF 217. The muffler 220 can reduce the amplitude of the sound pressure produced by the exhaust gases before the exhaust gases exit into the atmosphere. The exhaust gases can pass through one or more chambers or other sound-reducing structures within the muffler 220 before exiting the muffler via a muffler outlet to an exhaust tailpipe 231 of the exhaust system to the atmosphere.

[0046] The exhaust system includes an exhaust tuning valve 218, which is controlled to regulate a portion of the exhaust gas flowing through the muffler 220. The exhaust tuning valve 218 is installed downstream of the GPF 217 and upstream of the exhaust tailpipe 231 in the exhaust system, wherein the exhaust tuning valve 218 is coupled to the muffler 220 in a bypass passage 224 (a bypass passage 224 connected in parallel with the exhaust passage 235). Depending on whether the exhaust tuning valve 218 is in the open or closed position, exhaust gas leaving the exhaust system via the internal combustion engine 110 may pass through the valve under certain conditions. In one embodiment, when the exhaust tuning valve 218 is in the closed position, exhaust gas may exit only through the muffler 220 (e.g., to the atmosphere). When the exhaust tuning valve 218 is in the open position, at least a portion of the exhaust gas may pass through the muffler 220. Figure 2 The bypass passage 224 shown in the figure bypasses the muffler 220. In some examples, the exhaust tuning valve may operate partially open or partially closed, thereby allowing the exhaust to be partially transported through the muffler and partially transported through the exhaust tuning valve and into the bypass passage 224 before leaving the atmosphere.

[0047] Engine exhaust noise can be adjusted by changing the opening of exhaust tuning valve 218. The operator can control this via an HMI (e.g., connected to the vehicle's instrument panel and controller 212). Figure 1 The controller uses the HMI 133 input to indicate the desired engine noise level. When a higher exhaust noise level is required, the controller can increase the opening of the exhaust tuning valve 218 to increase the volume of exhaust flowing downstream of the GPF 217 to the exhaust tailpipe via the exhaust tuning valve 218. Because the exhaust flowing via the exhaust tuning valve 218 bypasses the muffler 220, the amplitude of the sound pressure generated by the exhaust may not be significantly reduced, and the perceived engine exhaust noise increases. Similarly, when a lower exhaust noise level is required, the controller can close the exhaust tuning valve 218 to deliver the entire exhaust volume to the exhaust tailpipe via the muffler 220, where the amplitude of the sound pressure can be attenuated and the operator perceives a lower engine exhaust sound.

[0048] The controller can perform diagnostics of the exhaust tuning valve 218 periodically or opportunistically during conditions when the vehicle (vehicle system 206) is unoccupied and the vehicle is not in motion. With the engine turned in reverse without fuel, the position of the exhaust tuning valve 218 is varied from a fully closed position to a fully open position at a constant rate and the intake air flow at each position of the exhaust tuning valve is estimated via the MAF sensor 210. A non-degradation of the exhaust tuning valve can be indicated in response to the intake air flow at each position of the exhaust tuning valve decreasing from a highest intake air flow at the fully open position to a lowest intake air flow at the fully closed position. Correspondingly, a degradation of the exhaust tuning valve can be indicated in response to the intake air flow at each position of the exhaust tuning valve being constant. Further, when the engine is turned in reverse, the intake electric supercharger 155 is operated in the reverse direction to increase the ambient air flow from the engine exhaust 235 to the engine intake manifold 244 via one or more engine cylinders 230.

[0049] During reverse rotation of the engine, the MAP sensor 213 can also be used to diagnose the exhaust trim valve 218. In one example, during reverse rotation of the engine, the exhaust trim valve 218 can first be commanded to the closed position and after a threshold duration of time has elapsed since the exhaust trim valve 218 was closed, the valve can be actuated to the fully open position. The threshold duration of time can be calibrated based on stabilization of intake manifold air pressure during reverse rotation of the engine. When the exhaust trim valve 218 is opened, there is an increase in the amount of air that is delivered into the engine system, resulting in a corresponding increase in intake manifold pressure. If a corresponding increase (e.g., more than 5%) in the MAP sensor 213 reading is observed after the exhaust trim valve 218 is opened, it can be concluded that the exhaust trim valve 218 can be actuated from the closed position to the open position and is not stuck. However, if no significant change (e.g., more than 5%) in the MAP sensor 213 reading is observed after the exhaust trim valve 218 is opened, it can be concluded that the exhaust trim valve 218 is stuck and can not be actuated. When the engine is rotated in reverse, the exhaust valve can be opened for a longer duration, in turn allowing for higher boost of the intake manifold at lower engine speeds. By operating the engine at lower engine speeds, power consumption from the electric motor can be reduced and the diagnosis can be performed with lower engine noise. In this way, during a first engine operating condition, the engine can be rotated in the forward direction with fuel injected via the fuel injectors 266 and the electric supercharger 155 can be rotated in the forward direction based on torque demand, and during a second engine operating condition, the engine can be rotated in the reverse direction without fuel injection via the electric motor and the electric supercharger 155 can be rotated in the reverse direction during diagnosis of the exhaust trim valve. In Figure 5 Details of the diagnostic method for the exhaust trim valve 218 are set forth in the detailed description.

[0050] The fuel system 219 can include a fuel tank coupled to a fuel pump system 221. It can be appreciated that the fuel tank can include the same fuel tank as depicted above at Figure 1 The fuel pump system 221 can include one or more pumps for pressurizing fuel delivered to the injectors (e.g., the example injectors 266 shown) of the engine 110. While only a single injector 266 is shown, additional injectors are provided for each cylinder. It will be appreciated that the fuel system 219 can be a no-return fuel system, a return fuel system, or various other types of fuel systems. The fuel tank can hold a variety of fuel blends, including fuels having a range of ethanol concentrations, such as various gasoline-ethanol blends, including E10, E85, gasoline, and the like, and combinations thereof.

[0051] Vapors generated in the fuel system 219 can be carried via a vapor recovery line 278 to a vapor emission control system 251 including a fuel vapor canister 222, after which the vapors are purged to the engine air intake 223. The vapor recovery line 278 can be coupled to the fuel tank via one or more conduits, and can include one or more valves for isolating the fuel tank during certain conditions.

[0052] The emission control system 251 can include one or more emission control devices, such as one or more fuel vapor canisters 222 filled with an appropriate adsorbent 286b, configured to temporarily trap fuel vapors (including vaporized hydrocarbons) during fuel tank refilling operations and "run losses" (i.e., fuel vaporized during vehicle operation). In one example, the adsorbent 286b used is activated carbon. The emission control system 251 can further include a canister vent path or vent line 227 that can carry gas exiting the canister 222 to the atmosphere when storing or trapping fuel vapors from the fuel system 219.

[0053] The canister 222 can include a buffer 222a (or buffer zone), each of which includes an adsorbent. As shown, the volume of the buffer 222a can be less than the volume of the canister 222 (e.g., a fraction of the volume of the canister). The adsorbent 286a in the buffer 222a can be the same or different than the adsorbent in the canister (e.g., both can include charcoal). The buffer 222a can be positioned within the canister 222 such that, during canister loading, fuel tank vapors are first absorbed within the buffer, and subsequently, when the buffer is saturated, additional fuel tank vapors are absorbed in the canister. In contrast, during canister purging, fuel vapors are first desorbed from the canister (e.g., to a threshold amount), and then from the buffer. In other words, the loading and unloading of the buffer is not in sync with the loading and unloading of the canister. Thus, the effect of the canister buffer is to dampen any fuel vapor peaks flowing from the fuel tank to the canister, in turn reducing the likelihood of any fuel vapor peaks going to the engine. One or more temperature sensors 232 can be coupled to and / or within the canister 222. As fuel vapors are absorbed by the adsorbent in the canister, heat is generated (absorption heat). Likewise, as fuel vapors are desorbed by the adsorbent in the canister, heat is consumed. In this way, the absorption and desorption of fuel vapors by the canister can be monitored and estimated based on temperature changes within the canister.

[0054] Vent line 227 can also allow fresh air to be drawn into canister 222 when stored fuel vapor is purged from fuel system 219 to engine intake manifold 223 via purge line 228 and purge valve 261. For example, purge valve 261 can be normally closed, but can be opened during certain conditions so that a vacuum from engine intake manifold 244 is provided to the fuel vapor canister for purging. In some examples, vent line 227 can include an air filter 259 disposed therein upstream of canister 222.

[0055] In some examples, the flow of air and vapor between canister 222 and atmosphere can be regulated by a canister vent valve 297 coupled within vent line 227. When included, canister vent valve 297 can be a normally open valve so that fuel tank isolation valve 252 (FTIV) can control venting of the fuel tank to atmosphere. FTIV 252 can be positioned between the fuel tank and fuel vapor canister 222 within vapor recovery line 278. FTIV 252 can be a normally closed valve that, when opened, allows fuel vapor from the fuel tank to be vented to fuel vapor canister 222. The fuel vapor can then be vented to atmosphere or purged to engine intake system 223 via canister purge valve 261.

[0056] Fuel system 219 can be operated in multiple modes by controller 212 by selectively adjusting various valves and solenoids. It can be appreciated that control system 214 can include the same control system as control system 190 depicted above at Figure 1 For example, the fuel system can be operated in a fuel vapor storage mode (e.g., during a fuel tank refueling operation and with the engine not burning air and fuel), where controller 212 can close canister purge valve (CPV) 261 while opening FTIV 252 to direct refueling vapors into canister 222 while preventing fuel vapors from being directed into the intake manifold.

[0057] As another example, the fuel system can be operated in a refueling mode (e.g., when a vehicle operator requests refueling of the fuel tank), where controller 212 can maintain canister purge valve 261 closed while opening isolation FTIV 252 to relieve pressure from the fuel tank, before allowing fuel to be added therein. Thus, FTIV 252 can be kept open during refueling operations to allow refueling vapors to be stored in the canister. After refueling is complete, FTIV 252 can be closed.

[0058] As another example, the fuel system can be operated in a filter tank purge mode (e.g., after the emission control device light-off temperature has been achieved and with the engine combusting air and fuel), where the controller 212 can close the FTIV 252 while opening the filter tank purge valve 261. Herein, vacuum created by the intake manifold of the operating engine can be used to draw fresh air through the vent line 227 and through the fuel vapor filter tank 222 to purge the stored fuel vapor into the intake manifold 244. In this mode, the purged fuel vapor from the filter tank is combusted in the engine. The purge can continue until the amount of stored fuel vapor in the filter tank is below a threshold value.

[0059] The controller 212 can form part of a control system 214. In some examples, the control system 214 can be the same as the control system 190 described in Figure 1 The control system 214 is shown receiving information from a plurality of sensors 216 (various examples of which are described herein) and sending control signals to a plurality of actuators 281 (various examples of which are described herein). As one example, the sensors 216 can include an exhaust gas sensor 237 located upstream of the emission control device 270, a pressure sensor 263 coupled across the particulate filter 217, temperature sensors 233, 226, and 229, a MAP sensor 213, a MAF sensor 210, and a filter tank temperature sensor 232. Other sensors, such as pressure sensors, temperature sensors, air / fuel ratio sensors, and composition sensors, can be coupled to various locations in the vehicle system 206. As another example, the actuators can include the throttle valve 262, the fuel tank isolation valve 252, the filter tank purge valve 261, and the filter tank vent valve 297, the exhaust tuning valve 218, and the electric supercharger actuators 155b. The controller can receive input data from the various sensors, process the input data, and in response to the processed input data trigger the actuators based on instructions or code programmed therein corresponding to one or more routines. In one example, during a vehicle off condition, the controller can timely implement a diagnostic method for the exhaust tuning valve 218. The controller can send a signal to each of the electric supercharger actuators 155b to rotate the electric supercharger in a reverse direction to continuously alter the opening of the exhaust tuning valve 218 while ambient air is flowed in via the exhaust tailpipe 231 and air flow is monitored via the MAF sensor 210. In another example, during a vehicle off condition, the controller can timely implement a diagnostic method for the intake air filter 215. The controller can send a signal to each of the electric supercharger actuators 155b to rotate the electric supercharger in a reverse direction to continuously alter the opening of the exhaust tuning valve 218 while ambient air is flowed in via the exhaust tailpipe 231 and air flow is monitored via the pressure sensor 263 and the MAF sensor 210.

[0060] In some examples, the controller can be placed in a reduced power mode or hibernate mode in which the controller maintains only essential functions and operates with lower battery consumption than in a corresponding wake mode. For example, the controller can be placed in hibernate mode after a vehicle shutdown event to perform a diagnostic routine for a duration of time after the vehicle shutdown event. The controller can have a wake input that allows the controller to return to the wake mode based on input received from one or more sensors. For example, opening a door of the vehicle can trigger a return to the wake mode.

[0061] For example, the wake capability can enable the circuit to wake the controller to perform a diagnostic of the intake air filter 215 in a timely manner. During a vehicle cutout condition, the engine can be made to turn without fuel, air flow through the exhaust system and air flow through the intake system can be compared to each other and to a baseline air flow, and in response to the air flow through the exhaust system being substantially equal to the air flow through the intake system and each of the air flow through the exhaust system and the air flow through the intake system being lower than the baseline air flow, an air flow blockage can be indicated. The air flow blockage can be indicated as a blocked intake air filter 215 based on an increase in the air flow through the exhaust system relative to the baseline air flow after opening an auxiliary path to atmosphere. The auxiliary path to atmosphere can be to atmosphere from downstream of the MAF sensor 210 via the canister purge line 228, the canister 222, and the canister vent path 227 of the evaporative emission control system 251, and can be opened by actuating each of the canister purge valves 261 to an open position and actuating the canister vent valve 297 to an open position.

[0062] The air flow through the exhaust system is estimated via a differential pressure (dP) sensor 263 coupled across the particulate filter 217, and the air flow through the intake system is estimated via the MAF sensor 210. During the diagnostic of the intake air filter 215, the intake electric supercharger 155 can also be operated in a reverse direction to carry ambient air from the engine exhaust tract 235 to the engine intake manifold 244 via one or more engine cylinders.

[0063] The diagnostic routine of the exhaust tuning valve and air filter can be performed in a vehicle configured as an autonomous vehicle, and is discussed below with respect to Figure 3 An example autonomous driving system is discussed. Figure 3 is a vehicle that can be operated as discussed above in Figure 1A block diagram of an exemplary autonomous driving system 300 of the vehicle system 100 described above. Herein, the vehicle system 100 will be referred to simply as the "vehicle." As shown, the autonomous driving system 300 includes a user interface device 310, a navigation system 315, at least one autonomous drive sensor 320, and an autonomous mode controller 325. It can be appreciated that the in-vehicle navigation system 315 can be the same as the in-vehicle navigation system 132 depicted at Figure 1 above, and the user interface device 310 can be the same as the HMI 133 depicted at Figure 1 above.

[0064] The user interface device 310 can be configured to present information to a vehicle occupant under conditions in which a vehicle occupant can be present. However, it can be appreciated that the vehicle can be autonomously operated under certain conditions in the absence of a vehicle occupant.

[0065] The presented information can include audible information or visual information. Additionally, the user interface device 310 can be configured to receive user input. Thus, the user interface device 310 can be located in a passenger cabin (not shown) of the vehicle. In some possible approaches, the user interface device 310 can include a touch-sensitive display screen.

[0066] The navigation system 315 can be configured to determine a current location of the vehicle using, for example, a global positioning system (GPS) receiver configured to triangulate the location of the vehicle relative to satellite or ground-based transmitter towers. The navigation system 315 can be further configured to form a route from the current location to a selected destination, and to display a map and present driving directions to the selected destination via, for example, the user interface device 310.

[0067] The autonomous drive sensors 320 can include any number of devices configured to produce signals that facilitate navigation of the vehicle. Examples of autonomous drive sensors 320 can include radar sensors, lidar sensors, vision sensors (e.g., video cameras), vehicle-to-vehicle infrastructure networks, etc. The autonomous drive sensors 320 can enable the vehicle to "see" the road and vehicle surroundings, and / or to navigate over various obstacles while the vehicle 100 is operating in autonomous mode. The autonomous drive sensors 320 can be configured to output sensor signals to, for example, the autonomous mode controller 325.

[0068] The autonomous mode controller 325 can be configured to control one or more subsystems 330 when the vehicle is operating in autonomous mode. Examples of subsystems 330 that can be controlled by the autonomous mode controller 325 can include a brake subsystem, a suspension subsystem, a steering subsystem, and a powertrain subsystem. The autonomous mode controller 325 can control any one or more of these subsystems 330 by outputting signals to control units associated with the subsystems 330. In one example, the brake subsystem can include an anti-lock brake subsystem configured to apply a braking force to one or more of the vehicle wheels. As discussed herein, applying a braking force to one or more of the vehicle wheels can be referred to as activating the brakes. To autonomously control the vehicle, the autonomous mode controller 325 can output appropriate commands to the subsystems 330. The commands can cause the subsystems to operate in accordance with the driving characteristics associated with the selected drive mode. For example, the driving characteristics can include how aggressive the vehicle accelerates and decelerates, how much space the vehicle leaves from the vehicle in front, how frequently the autonomous vehicle changes lanes, etc.

[0069] Figure 4A and Figure 4B An exemplary circuit 400 that can be used to reverse the rotational orientation of an electric motor is shown. The circuit 400 schematically depicts an H-bridge circuit that can be used to run a motor 410 in a first (forward) direction and, alternatively, in a second (reverse) direction. The circuit 400 includes a first (LO) side 420 and a second (HI) side 430. Side 420 includes transistors 421 and 422, while side 430 includes transistors 431 and 432. The circuit 400 also includes a power source 440.

[0070] In Figure 4A the transistors 421 and 432 are activated (energized) while the transistors 422 and 431 are turned off. In this configuration, the left leg lead 451 of the motor 410 is connected to the power source 440 and the right leg lead 452 of the motor 410 is grounded. In this way, the motor 400 can be run in the forward (or default) direction. When an engine is operated via the motor in the forward direction, the engine can be in a rotational start mode for initial combustion initiation. Additionally and / or alternatively, when an engine is operated via the motor in the forward direction, the engine (and motor or another motor) can be in a drive mode for driving a vehicle. It can be appreciated that in some examples, the engine can be rotated in the forward (e.g., default) direction under conditions where the vehicle is stationary and only the engine is desired to be rotated or spun in the forward direction without combustion.

[0071] In Figure 4BIn this configuration, transistors 422 and 431 are activated (energized), while transistors 421 and 432 are turned off. In this configuration, the right leg 452 of the motor 410 is connected to the power supply 440, and the left leg 451 of the motor 410 is grounded. In this way, the motor 410 can run in the reverse direction.

[0072] In this way, Figures 1-4A The components of -B provide a system for a hybrid vehicle, the system comprising: a vehicle; an engine; an electric machine coupled to a battery, the electric machine capable of rotating the engine; an intake tract comprising an intake air filter and a compressor; an exhaust tract comprising a particulate filter; a manifold air flow (MAF) sensor coupled to the intake tract; a differential pressure sensor coupled across the particulate filter; a canister flush line and a vent path coupling the intake tract to the atmosphere via a canister, the canister flush line comprising a canister purge valve (CPV) and the vent path comprising a canister vent valve (CVV). The vehicle further comprises a controller having computer readable instructions stored on a non-transitory memory for: obtaining a baseline air flow via the MAF sensor by using the electric machine to counter-rotate the engine when the intake air filter is installed for a first time; and after using the intake air filter for a threshold duration since the intake air filter was installed and while the engine is being rotated in reverse by the electric machine, obtaining a first intake air flow via the MAF sensor and a first exhaust air flow via the differential pressure sensor, comparing the first intake air flow, the first exhaust air flow, and the baseline air flow, and in response to the first intake air flow and the first exhaust air flow being equal to each other and lower than the baseline air flow, diagnosing the intake air filter in response to a change in the first exhaust air flow after the CPV and CVV are opened.

[0073] Figure 5 An exemplary method 500 that can be implemented to perform a diagnosis of exhaust tuning valves during engine non-combustion conditions is shown. The instructions for performing method 500 and the remainder of the methods included herein can be executed by a controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of an engine system, such as the sensors described above with reference to Figure 2 The controller can employ engine actuators of the engine system to adjust engine operation in accordance with the methods described below.

[0074] At 502, the method includes determining whether a condition for initiating a diagnosis of exhaust tuning valves (e.g., exhaust tuning valves 130) is satisfied. Figure 2Conditions for diagnosing the exhaust tuning valve (218) in the system. In one example, the conditions for initiating exhaust tuning valve diagnosis may include vehicle shutdown conditions when the vehicle is not occupied (no passengers are present in the vehicle). Seat force sensors, onboard cameras, and / or door sensing technology can be used to ensure the vehicle is not occupied. In another example, tuning valve diagnosis can be performed during autonomous vehicle mode when the vehicle is operated without a human driver and when the vehicle is not propelled by engine torque. Vehicle operation can be controlled from a remote location, or vehicle operation can be pre-programmed in the controller memory. During vehicle operation in an autonomous node, the diagnosis can be performed when the vehicle stops at a traffic signal or immediately after a driving cycle is completed. In another example, tuning valve diagnosis can be performed in response to waking up the controller after a predetermined duration following a cut-off event. Conditions for initiating exhaust tuning valve diagnosis include confirmation that engine sensors such as the MAF sensor and oxygen sensor are not deteriorated, and that there are generally no diagnostic codes (flags) set indicating deterioration of any engine components. Furthermore, before initiating exhaust tuning valve diagnostics, the controller can verify whether a predetermined duration has elapsed since the previous exhaust tuning valve diagnostic routine was performed. In some examples, such a predetermined duration may include one day, more than one day but less than two days, more than two days, etc. In other examples, the predetermined duration may include miles driven, hours of vehicle operation, or other parameters.

[0075] If it is determined that the conditions for initiating exhaust tuning valve diagnostics are not met, then at 503, the exhaust tuning valve diagnostic routine can be postponed until the conditions are met. In some examples, if the exhaust tuning valve diagnostic conditions are not met, then the current operating parameters can continue until the exhaust tuning valve diagnostic conditions are met. If the vehicle is being operated, then such operating parameters may include those via the fuel system (e.g., Figure 2 The fuel system 219 delivers fuel to one or more engine cylinders via fuel injectors, and the combustion of air and fuel occurs in the cylinders. The engine torque generated by the combustion in the engine cylinders can be used to propel the vehicle. Vapor generated in the fuel system can be transported via a vapor recovery line to an evaporative emission control system (e.g., fuel vapor tank) including a fuel vapor tank. Figure 2 The EVAP system 251 in the example can flush vapor stored in the filter canister into the engine intake manifold via a flushing line and a filter canister flushing valve (CPV) that regulates the vapor flow from the filter canister to the engine intake. The ventilation line allows fresh air to be drawn into the filter canister while the stored fuel vapor is flushed into the engine intake.

[0076] Electric supercharger (e.g., Figure 2An electric supercharger 155 in FIG. 1 can be coupled to a conduit in parallel with the intake tract, and can be used to provide the desired boost pressure using energy from the on-board energy storage device during conditions when the boost pressure provided by operation of the turbocharger (e.g., intake compressor 114 and exhaust turbine 116 in FIG. 1) is below the desired boost pressure. Figure 2 An electric supercharger 155 in FIG. 1 can be coupled to a conduit in parallel with the intake tract, and can be used to provide the desired boost pressure using energy from the on-board energy storage device during conditions when the boost pressure provided by operation of the turbocharger (e.g., intake compressor 114 and exhaust turbine 116 in FIG. 1) is below the desired boost pressure.

[0077] The opening of the exhaust tuning valve can be adjusted based on a desired engine noise level selected by an operator (e.g., via a human-machine interface). When a higher exhaust noise level is desired, the controller can increase the opening of the exhaust tuning valve to increase the volume of exhaust that flows to the exhaust tailpipe via the exhaust tuning valve, bypassing the muffler. Because the exhaust that flows via the exhaust tuning valve bypasses the muffler, the amplitude of the sound pressure generated by the exhaust can not be significantly reduced, in turn resulting in an increased perceived engine exhaust noise.

[0078] If it is determined that the conditions for initiating the exhaust tuning valve diagnosis are met, at 504 the routine includes causing the engine to rotate or turn in a reverse direction at a predetermined rotational speed (e.g., a predetermined RPM) without fueling. Causing the engine to rotate in a reverse direction can include causing the engine to rotate in an opposite direction than when the engine is operated to combust air and fuel. Causing the engine to rotate in a reverse direction without fueling can include routing a flow of air through the exhaust system, the engine, and the intake manifold (in that order). Causing the engine to rotate in a reverse direction without fueling can include causing the engine to rotate via a motor (e.g., motor 120 in FIG. 1), where the motor can be powered via an on-board energy storage device (e.g., energy storage device 150 in FIG. 1), such as a battery. Figure 1 If it is determined that the conditions for initiating the exhaust tuning valve diagnosis are met, at 504 the routine includes causing the engine to rotate or turn in a reverse direction at a predetermined rotational speed (e.g., a predetermined RPM) without fueling. Causing the engine to rotate in a reverse direction can include causing the engine to rotate in an opposite direction than when the engine is operated to combust air and fuel. Causing the engine to rotate in a reverse direction without fueling can include routing a flow of air through the exhaust system, the engine, and the intake manifold (in that order). Causing the engine to rotate in a reverse direction without fueling can include causing the engine to rotate via a motor (e.g., motor 120 in FIG. 1), where the motor can be powered via an on-board energy storage device (e.g., energy storage device 150 in FIG. 1), such as a battery. Figure 1 If it is determined that the conditions for initiating the exhaust tuning valve diagnosis are met, at 504 the routine includes causing the engine to rotate or turn in a reverse direction at a predetermined rotational speed (e.g., a predetermined RPM) without fueling. Causing the engine to rotate in a reverse direction can include causing the engine to rotate in an opposite direction than when the engine is operated to combust air and fuel. Causing the engine to rotate in a reverse direction without fueling can include routing a flow of air through the exhaust system, the engine, and the intake manifold (in that order). Causing the engine to rotate in a reverse direction without fueling can include causing the engine to rotate via a motor (e.g., motor 120 in FIG. 1), where the motor can be powered via an on-board energy storage device (e.g., energy storage device 150 in FIG. 1), such as a battery. Figures 4A-4B If it is determined that the conditions for initiating the exhaust tuning valve diagnosis are met, at 504 the routine includes causing the engine to rotate or turn in a reverse direction at a predetermined rotational speed (e.g., a predetermined RPM) without fueling. Causing the engine to rotate in a reverse direction can include causing the engine to rotate in an opposite direction than when the engine is operated to combust air and fuel. Causing the engine to rotate in a reverse direction without fueling can include routing a flow of air through the exhaust system, the engine, and the intake manifold (in that order). Causing the engine to rotate in a reverse direction without fueling can include causing the engine to rotate via a motor (e.g., motor 120 in FIG. 1), where the motor can be powered via an on-board energy storage device (e.g., energy storage device 150 in FIG. 1), such as a battery. Figure 2 If it is determined that the conditions for initiating the exhaust tuning valve diagnosis are met, at 504 the routine includes causing the engine to rotate or turn in a reverse direction at a predetermined rotational speed (e.g., a predetermined RPM) without fueling. Causing the engine to rotate in a reverse direction can include causing the engine to rotate in an opposite direction than when the engine is operated to combust air and fuel. Causing the engine to rotate in a reverse direction without fueling can include routing a flow of air through the exhaust system, the engine, and the intake manifold (in that order). Causing the engine to rotate in a reverse direction without fueling can include causing the engine to rotate via a motor (e.g., motor 120 in FIG. 1), where the motor can be powered via an on-board energy storage device (e.g., energy storage device 150 in FIG. 1), such as a battery. Figure 2The CPV 261 in the figure remains closed to ensure that air is not delivered to the evaporative emission system and / or fuel system. Furthermore, although not explicitly stated, for vehicles equipped with exhaust gas recirculation (EGR) (e.g., high-pressure EGR and / or low-pressure EGR), one or more valves controlling exhaust gas recirculation may be commanded or maintained closed.

[0079] At position 506, an electric supercharger (e.g., Figure 2 The electric supercharger 155 rotates in the reverse direction. During periods when the boost pressure provided by operating the turbocharger is lower than the desired boost pressure, the electric supercharger can be operated in the forward, default direction to provide the desired boost. The reverse rotation of the electric supercharger generates lower pressure at the exhaust manifold, thereby promoting airflow through the exhaust system, engine, and intake manifold. The controller can send signals to the electric supercharger actuator (e.g., Figure 1 The actuator 155b in the middle is used to utilize the energy storage device (e.g., connected to the electric supercharger) to power the electric supercharger. Figure 1 The electric supercharger is actuated by energy stored in the energy storage device 250. The rotational speed of the electric supercharger during the diagnostic routine can be lower than the rotational speed of the electric supercharger when it is operated to compensate for the lag of the mechanical turbocharger. In one example, the rotational speed of the electric supercharger during the diagnostic routine can be 2500 RPM. By operating the electric supercharger at a lower speed, power consumption can be reduced, and noise generated during the operation of the electric supercharger can also be reduced. In one example, step 506 of method 500 can be optional, and the exhaust tuning valve diagnostic can be performed without rotating the electric supercharger. When the engine is reversed during the exhaust tuning valve diagnostic routine, the electric supercharger can be kept in a deactivated condition. At 508, the opening of the exhaust tuning valve can be changed from a fully open position (fully open throttle) to a fully closed position. The controller can send signals to the actuator coupled to the exhaust tuning valve to actuate the valve to the fully open position, and subsequently actuate the valve from the fully open position to the fully closed position. The opening of the exhaust tuning valve can decrease from the fully open position to the fully closed position at a constant rate (dE / dt). In one example, the scanning rate of the disc in the exhaust tuning valve can be 5 seconds / 90-degree stroke.

[0080] Changing the position of the exhaust tuning valve alters the airflow into the exhaust system. In one example, when the exhaust tuning valve is fully open, ambient air can flow through the muffler and bypass passages (e.g., due to the low pressure generated in the engine intake manifold by the counter-rotation of the engine and electric supercharger) to the exhaust system. Figure 2Each of the bypass passages 224) into the exhaust manifold. Air entering the exhaust manifold can continue to flow via the engine cylinders and then into the intake manifold. Ambient air can then exit the engine system via the intake tract. As the exhaust tuning valve is decreased in opening, the path for air flow via the bypass passages narrows, and air flow is restricted to the path via the muffler, and the total volume of air entering the exhaust manifold can decrease. After the exhaust tuning valve is fully closed, air can no longer flow into the exhaust manifold via the bypass passages, and thus the total volume of air entering the exhaust manifold can further decrease.

[0081] Alternatively, the controller can send a signal to an actuator coupled to the exhaust tuning valve to first actuate the position of the exhaust tuning valve to the fully closed position, and then actuate the position of the valve from the fully closed position to the fully open position. The opening of the exhaust tuning valve can increase from the fully closed position to the fully open position at a constant rate.

[0082] At 510, for each position of the exhaust tuning valve, the amount of air flowing through the exhaust manifold, and then through the cylinders and intake manifold, can be estimated via the manifold air flow sensor (e.g., MAF sensor 210) in the intake tract. The amount of air flowing through the engine components can be directly proportional to the degree of opening of the exhaust tuning valve. In one example, the amount of air entering the exhaust manifold can increase as the exhaust tuning valve opening increases, and correspondingly, the amount of air entering the exhaust manifold can decrease as the exhaust tuning valve opening decreases. Thus, as the opening of the exhaust tuning valve decreases from the large open position to the fully closed position, the MAF sensor reading indicative of intake air flow can proportionally decrease. Figure 2

[0083] At 511, the rate of change (dF / dt) of the estimated intake air flow based on the MAF sensor reading is estimated over time. The estimation of dF / dt can be performed during the time period in which the opening of the exhaust tuning valve decreases from the fully open position to the fully closed position (at a constant rate). In one example, the MAF sensor output can be sampled periodically (e.g., at evenly spaced intervals), beginning when the exhaust tuning valve is in the large open position (e.g., 100% open) and continuing until the exhaust tuning valve is in the fully closed position (e.g., 0% open). During this time, the MAF sensor output can be sampled when the exhaust tuning valve is 90% open, 80% open, 70% open, etc. Each time the MAF sensor output is sampled, the sampled output can be stored in the memory of the controller. In some examples, the corresponding position of the exhaust tuning valve can also be stored with the MAF output at that exhaust tuning valve position.

[0084] ​At 512, the routine includes determining whether the rate of change of intake air flow (dF / dt) and the rate of change of exhaust tuning valve opening (dE / dt) are related. When the exhaust tuning valve opening is reduced from a fully open position to a fully closed position at a constant rate (dE / dt), the intake air flow can be proportionally reduced. In one example, the routine can determine whether dF / dt is directly proportional to dE / dt.

[0085] In another example, the routine can include determining whether the MAF sensor reading is highest at the exhaust tuning valve fully open position and the MAF sensor reading is lowest at the exhaust tuning valve closed position. As described above, at the exhaust tuning valve fully open position, a highest MAF sensor reading is expected corresponding to a highest volume of ambient air entering the engine system. Also, at the exhaust tuning valve closed position, a lowest MAF sensor reading is expected corresponding to a lowest volume of ambient air entering the engine system.

[0086] The highest MAF sensor reading described above can be a sampled MAF sensor output having a highest value among all sampled MAF sensor outputs collected during the time of scanning the exhaust tuning valve from the fully open position to the fully closed position. The lowest MAF sensor reading described above can be a sampled MAF sensor output having a lowest value among all sampled MAF sensor outputs collected during the time of scanning the exhaust tuning valve from the fully open position to the fully closed position.

[0087] In another example, the routine can include determining whether the MAF sensor reading at each position of the exhaust tuning valve reading (e.g., when the tuning valve is open 100%, 75%, 50%, 25%, and 0%) is substantially equal to an expected intake air flow. In one example, substantially equal can include the MAF sensor reading being within 5% of the expected intake air flow. The controller can use a lookup table to determine the expected intake air flow corresponding to the exhaust tuning valve opening. For example, the input to the lookup table can be the exhaust tuning valve opening, where the output is the intake air flow. The expected intake air flow can be proportionally reduced in the case of a reduced tuning valve opening.

[0088] If it is determined that the rate of change of intake air flow (dF / dt) and the rate of change of exhaust tuning valve opening (dE / dt) are related (directly proportional), it can be inferred that the exhaust tuning valve was successfully actuated from the fully open position to the fully closed position and was not stuck at any position between the fully open position and the closed position.

[0089] If it is determined that the MAF sensor readings are highest at the wide open position of the exhaust tuning valve and the MAF sensor readings are lowest at the closed position of the exhaust tuning valve, it can also be inferred that the exhaust tuning valve was successfully actuated from the fully open position to the fully closed position. Moreover, if for each position of the exhaust tuning valve, the MAF sensor readings substantially equal the expected intake air flow, it can be inferred that the exhaust tuning valve is not stuck at any position between the fully open position and the fully closed position. Accordingly, at 514, the exhaust tuning valve can be indicated as not degraded. At 516, the diagnostic routine is completed and each of the engine and the electric supercharger can be stopped from rotating. The controller can send a signal to the motor that powers the engine to stop rotating the engine. The controller can also send a signal to the actuator coupled to the electric supercharger to pause operation of the electric supercharger.

[0090] If at 512 it is determined that the rate of change of intake air flow (dF / dt) and the rate of change of the opening of the exhaust tuning valve (dE / dt) are not proportional, it can be inferred that the exhaust tuning valve can not have been actuated from the fully open position to the fully closed position. If it is determined that the MAF sensor readings are not highest at the wide open position of the exhaust tuning valve and / or the MAF sensor readings are not lowest at the closed position of the exhaust tuning valve, the MAF sensor readings do not substantially equal the expected intake air flow, it can be inferred that the exhaust tuning valve is degraded. At 518, a diagnostic code (flag) indicating that the exhaust tuning valve is degraded can be set. In one example, valve degradation can include the valve being stuck at a fixed position (e.g., the fully open position, the fully closed position, or a position between the fully open position and the fully closed position) even when the valve is actuated to move to a different position. In another example, valve degradation can include a leak in the valve causing air to flow through a bypass passage and the valve even when the valve is commanded to reach the fully closed position.

[0091] Because the valve is degraded, it can not be possible to properly adjust the position of the valve corresponding to the exhaust noise setting, thereby adversely affecting the driving experience. Accordingly, in response to the indication of the exhaust tuning valve being degraded, at 520, the engine can disable engine exhaust noise regulation via adjustment of the exhaust tuning valve until the valve has been serviced.

[0092] In this manner, when operating the vehicle without a human driver and when the vehicle is not being propelled by engine torque, during a first engine operating condition, the position of the exhaust tuning valve can be adjusted based on an operator selected noise pattern and, during a second engine operating condition, the opening of the exhaust tuning valve can be adjusted from a fully closed position to a fully open position, the intake air flow corresponding to each opening of the exhaust tuning valve can be estimated via the MAF sensor, and the exhaust tuning valve can be diagnosed based on changes in the intake air flow and the increase in the opening of the exhaust tuning valve. The first engine operating condition includes the engine being rotated in a forward direction with fuel being injected via fuel injectors and the electric supercharger being rotated in a forward direction based on a torque demand, and the second engine operating condition includes the engine being rotated in a reverse direction without fuel via an electric machine.

[0093] Figure 6 An exemplary timeline 600 is shown illustrating a diagnosis of an exhaust tuning valve (e.g., exhaust tuning valve 218 in Figure 2 FIG. 2). The horizontal (x-axis) represents time and the vertical markers ti - t4 identify active times in an operating routine of the electric supercharger.

[0094] A first plot (line 602) illustrates a change in vehicle speed over time. A second plot (line 604) illustrates a rotational direction of the engine. During engine operation, for example, with air-fuel combustion in the engine cylinders, the engine can be rotated in a forward, default direction with fuel being supplied to the engine cylinders via fuel injectors. Alternatively, the engine can be rotated in a reverse direction without fuel, for example, via an electric machine coupled to a hybrid electric vehicle (HEV). A third plot (line 606) illustrates an electric supercharger (e.g., electric supercharger 208 in FIG. 2) coupled to a duct in parallel with an intake manifold downstream of an intake compressor and upstream of a charge air cooler (CAC). The fourth plot (line 608) illustrates an exhaust tuning valve (e.g., exhaust tuning valve 218 in FIG. 2) coupled to the duct downstream of the electric supercharger and upstream of the CAC. Figure 1The fourth plot (line 608) shows operation of an electric motor coupled to a hybrid electric vehicle (HEV). The electric motor can be operated to provide motor torque to propel the HEV. The fifth plot (line 610) shows the opening of the exhaust tuning valve. The sixth plot (line 612) shows the volume of intake air flow estimated based on input from a manifold air flow (MAF) sensor. The dashed and dotted line 613 shows the expected intake air flow corresponding to the opening of the exhaust tuning valve at any given point in time. The controller uses a lookup table to estimate the expected intake air flow corresponding to each opening of the exhaust tuning valve (e.g., at 100%, 75%, 50%, 25%, and 0% of the tuning valve opening), with the exhaust valve opening as input to the lookup table and the expected intake air flow as output from the lookup table. The seventh plot (dashed line 616) shows a flag that represents a diagnostic code set to indicate a degraded exhaust tuning valve.

[0095] Prior to time tl, the vehicle is operated via engine torque. The engine is driven by combustion and is rotated in the forward direction. The electric supercharger is rotated in the forward direction to provide the desired boost pressure based on torque demand. Intake manifold air flow during engine combustion is estimated based on the reading of the MAF sensor. The HEV electric motor is not operated for engine rotation or vehicle propulsion. The exhaust tuning valve is maintained at a fixed position between the fully open and fully closed positions based on the desired engine exhaust noise setting (via the on-board human machine interface by the operator). Because the exhaust tuning valve is not indicated to be degraded, the flag is maintained in the closed position.

[0096] At time tl, the vehicle speed is reduced to zero and between times tl and t2, the vehicle is no longer operated using engine torque and / or electric motor torque (vehicle cut-off condition begins). Accordingly, at time tl, the engine is turned off by pausing fuel injection and spark to the engine cylinders. The electric supercharger is no longer operated between times tl and t2. When the engine is turned off, intake air flow is no longer monitored via the MAF sensor.

[0097] At time t2, after a threshold duration has elapsed since the vehicle was shut off at time ti, a diagnosis of the exhaust tuning valve is initiated by the wake-up controller. The controller sends a signal to the HEV motor to cause the engine to turn in a reverse direction without fueling. Also, the controller sends a signal to an actuator coupled to the electric supercharger to cause the electric supercharger to spin in a reverse direction. As the engine and electric supercharger spin in their respective reverse directions, a lower pressure is created at the engine exhaust manifold and ambient air can enter the engine system via the exhaust passage. The controller then sends a signal to an actuator coupled to the exhaust tuning valve to move the exhaust tuning valve to a fully closed position. Between t2 and t3, air flows into the engine system via the muffler with the exhaust tuning valve closed and the MAF reading can stabilize.

[0098] At time t3, the controller sends a signal to the actuator coupled to the exhaust tuning valve to gradually increase the exhaust tuning valve opening from the fully closed position at a constant rate. The rate of increase of the exhaust tuning valve opening is 18 degrees / second. Between times t3 and t4, as the position of the exhaust tuning valve increases, there is a corresponding increase in the flow of air into the engine system via the exhaust passage and then to the intake manifold via the engine cylinders. The actual air flow through the engine system corresponding to each position of the exhaust tuning valve is monitored via the MAF sensor. The actual air flow (line 612) is compared to the expected air flow (line 613) corresponding to the opening of the exhaust tuning valve at any given point in time. It is observed that the actual air flow correlates with the expected air flow and the MAF sensor reading increases proportionally to the opening of the exhaust tuning valve.

[0099] Thus, at the end of the diagnostic routine at time t4, based on the observation that the actual air flow correlates with the expected air flow and the MAF sensor reading corresponds to a highest at the fully open position of the exhaust tuning valve and a lowest at the fully closed position of the exhaust tuning valve, it is concluded that the exhaust tuning valve is not deteriorated (not stuck anywhere and / or does not have a leak). Because it is concluded that the exhaust tuning valve is not deteriorated, the flag is maintained in the off condition.

[0100] At time t4, at the end of the diagnostic routine, the exhaust tuning valve is actuated back to the position of the valve prior to the initiation of the diagnostic routine, e.g., the position of the valve prior to time t3. Also, at time t4, the controller sends a signal to each of the HEV motor and electric supercharger actuators to pause operation and stop the rotation of the engine and electric supercharger, respectively. After time t4, the engine torque and / or motor torque is not used to propel the vehicle and the engine is maintained in the off condition until the vehicle is subsequently turned on.

[0101] If the exhaust trim valve has deteriorated, then between times t3 and t4, the MAF sensor reading does not increase proportionally with the increase in exhaust trim valve opening. As shown by the dashed line 611, if the exhaust trim valve is stuck open at a particular position, then even if the controller sends a signal to the actuator coupled to the exhaust trim valve to gradually actuate the valve from the fully closed position to the fully open position, the valve opening does not change appreciably. Accordingly, as shown by the dashed line 614, the MAF reading remains substantially constant for the duration of the diagnostic routine between times t3 and t4. From the substantially constant MAF sensor reading, it can be inferred that the exhaust trim valve has deteriorated and the flag indicating a deteriorated exhaust trim valve is set at time t4.

[0102] In this way, the engine is rotated in a reverse direction and the intake electric supercharger is rotated in a reverse direction to draw air into the engine through the exhaust passage and subsequently deliver the air to the atmosphere through the intake passage, the opening of the exhaust trim valve is varied, and whether the exhaust trim valve has deteriorated is diagnosed based on the correlation between the opening of the exhaust trim valve and the flow of air through the intake passage.

[0103] Figure 7A - 7B shows an exemplary method 700 that can be implemented to perform a diagnosis of the intake air filter. Similar to the diagnosis of the exhaust trim valve, the diagnosis of the intake air filter can be performed by reversing the engine without fuel during an engine non-combustion condition. In one example, the intake air filter diagnosis and the exhaust trim valve diagnosis can be continuously performed during a vehicle shut-off condition.

[0104] At 702, the routine includes determining whether a condition for initiating a diagnosis of the intake air filter (e.g., the engine is off, the engine is running, the engine is running in a non-combustion condition, etc.) is met. Figure 2diagnosis can be implemented during autonomous vehicle mode when the vehicle is operated without a human driver and when the vehicle is not propelled by engine torque. The vehicle operation can be controlled from a remote location or the vehicle operation can be pre-programmed in the controller memory. The diagnosis can be implemented opportunistically when the vehicle is stopped at a traffic signal or shortly after a drive cycle is completed during vehicle operation in autonomous mode. In another example, the intake air filter diagnosis can be implemented in response to a wake-up of the controller after a predetermined duration after a shut-off event. Another condition for initiating the intake air filter diagnosis is that the soot load on the exhaust particulate filter (PF) is below a threshold soot load. The threshold soot load can correspond to a load on the PF that can not affect the output of a differential pressure (dP) sensor coupled across the PF. For example, the threshold soot load can correspond to the soot load remaining on the PF at the end of PF regeneration.

[0105] The expected air flow through the intake manifold can be estimated as a function of the intake throttle opening, and the actual air flow through the intake manifold can be estimated based on input from a manifold air flow (MAF) sensor. Due to clogging in the intake air filter, the actual air flow through the intake manifold can decrease below the expected air flow. If the actual air flow is detected to be below the expected air flow, a diagnosis of the intake air filter can be opportunistically implemented.

[0106] The expected engine torque output can be estimated based on engine operating conditions including engine speed, engine load, engine temperature, etc. A clogged intake air filter can reduce the amount of air entering the cylinders for combustion, which in turn can adversely affect the engine torque output. Thus, a decrease in the engine output relative to the expected engine output (engine stall) can trigger the intake air filter diagnosis.

[0107] Conditions for initiating a diagnosis of the intake air filter include confirmation that engine sensors, such as the MAF sensor, dP sensor, oxygen sensor, etc., are not deteriorated, and that no diagnostic codes (flags) are set that generally indicate deterioration of any engine components. In addition, prior to initiating the intake air filter diagnosis, the controller can verify that a predetermined duration has elapsed since a previous intake air filter diagnostic routine. In some examples, such a predetermined duration can include one day, more than one day but less than two days, more than two days, etc. In other examples, the predetermined duration can include miles driven, hours of vehicle operation, or other parameters.

[0108] If it is determined that the conditions for initiating the intake air filter diagnosis are not met, at 704, the intake air filter diagnostic routine can be deferred until the conditions are met. In some examples, if the intake air filter diagnostic conditions are not met, the current operating parameters can continue until the intake air filter diagnostic conditions are met. During combustion, the intake throttle can be opened to allow air to flow into the intake manifold via the intake air filter. The air filter removes dust, dirt, and other airborne particulates from the air entering the intake manifold. Fuel can be delivered to one or more engine cylinders via fuel injectors of a fuel system (e.g., fuel system 219 in Figure 2 Engine torque can be generated by combustion in the engine cylinders and used to propel the vehicle. Vapors generated in the fuel system can be carried to an evaporative emission control system (e.g., EVAP system 251 in Figure 2 including a fuel vapor can via a purge line, a canister purge valve (CPV) that regulates the flow of vapors from the canister to the engine intake. A vent line can allow fresh air to be drawn into the canister as the stored fuel vapors are purged to the engine intake.

[0109] An electric supercharger (e.g., electric supercharger 155 in Figure 2 may provide a desired boost pressure during conditions when the boost pressure provided by operating a turbocharger (e.g., intake compressor 114 and exhaust turbine 116 in Figure 2 may provide a desired boost pressure during conditions when the boost pressure provided by operating a turbocharger (e.g., intake compressor 114 and exhaust turbine 116 in

[0110] If it is determined that the conditions for initiating an intake air filter diagnosis are met, the method 700 proceeds to 706 and includes causing the engine to rotate or turn in a reverse direction at a predetermined rotational speed (e.g., a predetermined RPM) without fueling. Causing the engine to rotate without fueling can include causing the engine to rotate in a direction opposite to when the engine is operated to combust air and fuel. Causing the engine to rotate in the reverse direction without fueling can include routing a flow of air through the exhaust system, the engine, and the intake manifold (in that order). Causing the engine to rotate in the reverse direction without fueling can include causing the engine to rotate via a motor (e.g., motor 120 in Figure 1 , where power can be supplied to the motor via an on-board energy storage device (e.g., energy storage device 150 in Figure 1 , such as a battery). To cause the engine to rotate in reverse, a H-bridge circuit, such as depicted at Figures 4A-4B , can be utilized. Rotational starting of the engine without fueling while causing the engine to turn in reverse is performed under a predetermined set of conditions, including engine rotational speed, duration of engine rotational starting, intake throttle position, and exhaust tuning valve position. The rotational speed of the engine can be controlled to a predetermined rotational speed via the motor. In one example, the predetermined rotational speed can be less than 500 rpm. The predetermined engine conditions can include a set of conditions under which robust measurements of air flow can be obtained via a MAF sensor (e.g., MAF sensor 210 in Figure 2 , when causing the engine to turn in reverse. In one example, the predetermined conditions can be calibrated by the controller prior to initiating the diagnostic routine based on a desired air flow via the MAF sensor. Further, to cause the engine to rotate in the reverse direction without fueling, valve timing can be controlled to a default value.

[0111] While not explicitly shown, for vehicles equipped with exhaust gas recirculation (EGR) (e.g., high pressure EGR and / or low pressure EGR), one or more valves controlling exhaust gas recirculation can be commanded or maintained closed.

[0112] At 708, an electric supercharger can be caused to rotate in a reverse direction. The electric supercharger can be coupled to a pipe in parallel with an intake tract, the pipe being coupled to the intake tract downstream of an intake compressor and upstream of an air charge cooler. The electric supercharger can be caused to rotate in the reverse direction by causing the electric supercharger to rotate in a direction opposite to when the electric supercharger is operated to compress air (e.g., Figure 2The electric supercharger can be operated in the reverse direction to provide a boost pressure that is lower than the desired boost pressure when conditions exist that the boost pressure provided by the intake compressor 114 and exhaust turbine 116 in the engine 100 is lower than the desired boost pressure. The reverse rotation of the electric supercharger creates lower pressure at the exhaust manifold, facilitating air flow through the exhaust system, engine, and intake manifold (in that order). The controller can send a signal to the electric supercharger actuator (e.g., actuator 155b in the engine 100) to actuate the electric supercharger using energy from an energy storage device (e.g., energy storage device 250 in the engine 100) coupled to the electric supercharger. The electric supercharger can be operated at a predetermined rotational speed at which a robust measurement of air flow can be obtained via the MAF sensor while the engine is rotated in reverse and the electric supercharger is rotated in reverse. In one example, the predetermined rotational speed of the electric supercharger can be calibrated by the controller based on the desired air flow via the MAF sensor prior to starting a diagnostic routine. During a cranking of the engine with the engine un-fueled, while the engine is rotated in reverse and the electric supercharger is rotated in reverse, a low pressure zone is created within the exhaust manifold and ambient air can enter and flow through the exhaust manifold, engine cylinders, and intake manifold (in that order) via the exhaust tailpipe, and then the air can escape to the atmosphere via the intake tract. In one example, step 708 of the method 700 can be optional and the diagnostic of the intake air filter can be performed without rotating the electric supercharger. The electric supercharger can be maintained in a deactivated condition when the engine is rotated in reverse during the intake air filter diagnostic routine to carry ambient air into the exhaust manifold via the exhaust tailpipe. Figure 1 Figure 1 The electric supercharger can be operated in the reverse direction to provide a boost pressure that is lower than the desired boost pressure when conditions exist that the boost pressure provided by the intake compressor 114 and exhaust turbine 116 in the engine 100 is lower than the desired boost pressure. The reverse rotation of the electric supercharger creates lower pressure at the exhaust manifold, facilitating air flow through the exhaust system, engine, and intake manifold (in that order). The controller can send a signal to the electric supercharger actuator (e.g., actuator 155b in the engine 100) to actuate the electric supercharger using energy from an energy storage device (e.g., energy storage device 250 in the engine 100) coupled to the electric supercharger. The electric supercharger can be operated at a predetermined rotational speed at which a robust measurement of air flow can be obtained via the MAF sensor while the engine is rotated in reverse and the electric supercharger is rotated in reverse. In one example, the predetermined rotational speed of the electric supercharger can be calibrated by the controller based on the desired air flow via the MAF sensor prior to starting a diagnostic routine. During a cranking of the engine with the engine un-fueled, while the engine is rotated in reverse and the electric supercharger is rotated in reverse, a low pressure zone is created within the exhaust manifold and ambient air can enter and flow through the exhaust manifold, engine cylinders, and intake manifold (in that order) via the exhaust tailpipe, and then the air can escape to the atmosphere via the intake tract. In one example, step 708 of the method 700 can be optional and the diagnostic of the intake air filter can be performed without rotating the electric supercharger. The electric supercharger can be maintained in a deactivated condition when the engine is rotated in reverse during the intake air filter diagnostic routine to carry ambient air into the exhaust manifold via the exhaust tailpipe.

[0113] ​At 710, the controller can retrieve a baseline air flow from an on-board database. In one example, the baseline air flow can be estimated via the MAF sensor by starting the engine in a reverse direction without fuel and spinning the electric supercharger in a reverse direction after installation of the air cleaner. In one example, installing the air cleaner can include assembling the air cleaner in the engine at a manufacturing facility. In another example, installing the air cleaner can include replacing an old air cleaner with a new air cleaner at a service location. The baseline air flow can be estimated within a first threshold duration since installation of the intake air cleaner, while a diagnosis of the air cleaner can be performed when the intake air cleaner has been used for more than a second threshold duration, the second threshold duration being longer than the first threshold duration. In one example, the first threshold duration can be 1 day since installation of the air cleaner. In another example, the second threshold duration can be 30 days since installation of the air cleaner. Alternatively, the baseline air flow can be estimated within a first threshold distance (of the vehicle) since installation of the intake air cleaner, while a diagnosis of the air cleaner can be performed when the intake air cleaner has been used for more than a second threshold distance, the second threshold distance being longer than the first threshold distance. In one example, the first threshold distance can be 30 miles since installation of the air cleaner. In another example, the second threshold distance can be 300 miles since installation of the air cleaner.

[0114] The baseline air flow can be obtained while operating the engine and the electric supercharger under a predetermined set of conditions, including engine speed, duration of engine spin-up, intake throttle position, exhaust valve position, and rotational speed of the electric supercharger. For example, the predetermined set of conditions under which the baseline air flow is estimated is the same as the predetermined set of conditions under which the engine is spun in step 706 and the electric supercharger is spun in step 708.

[0115] In one example, the baseline air flow can be a single baseline air flow estimated via the intake MAF sensor during engine operation under the predetermined set of conditions. In another example, there can be two separate baseline air flows: a first baseline intake air flow estimated via the intake MAF sensor, and a second baseline exhaust air flow estimated via an exhaust differential pressure (dP) sensor coupled across the exhaust particulate filter. Each of the first baseline intake air flow and the second baseline exhaust air flow can be estimated during engine operation under the predetermined set of conditions. For an undegraded engine system, because the same ambient air flow flows through each of the exhaust runner and the intake manifold during reverse rotation of the engine (during non-combustion conditions), the air flow estimated by the dP sensor can be substantially equal to the air flow estimated by the MAF sensor. Thus, the first baseline intake air flow and the second baseline exhaust air flow can be substantially equal to each other. In one example, substantially equal includes the first baseline intake air flow being within a threshold margin of the second baseline exhaust air flow. For example, the threshold margin can be 5%. Also, the first baseline intake air flow can be equal to the second baseline exhaust air flow.

[0116] At 712, the method proceeds to a diagnostic routine of the intake air filter, and estimates the air flow through the intake system via the MAF sensor (intake air flow) and estimates the air flow through the exhaust system via the dP sensor (exhaust air flow). In the absence of a clog or leak in the engine system, the same amount of air can flow through each of the exhaust runner, the engine cylinder, and the intake runner.

[0117] At 714, the method includes determining whether there is a correlation between the intake air flow, the exhaust air flow, and the baseline air flow. In one example, the controller can determine whether the intake air flow, the exhaust air flow, and the baseline air flow are substantially equal to each other. As described earlier, substantial equality can include each of the factors, intake air flow, exhaust air flow, and baseline air flow, being within a threshold margin of the other two factors. In one example, the threshold margin can be 5%. In another example, it can be determined whether the intake air flow, the exhaust air flow, and the baseline air flow are equal to each other.

[0118] In one example, if there are separate intake baseline air flow and exhaust baseline air flow, the controller can determine whether the intake air flow, the exhaust air flow, the intake baseline air flow, and the exhaust baseline air flow are substantially equal to each other.

[0119] If it is determined that there is a correlation between the intake air flow, the exhaust air flow, and the baseline air flow and that they are substantially equal to one another, it can be inferred that the amount of ambient air flowing through the engine components at the time of diagnosis is substantially equal to the amount of ambient air flowing through the engine components after the air cleaner is installed. Thus, it can be inferred that the air cleaner is not clogged, and at 716, the controller can indicate that the air cleaner is not degraded. If the intake air flow, the exhaust air flow, the intake baseline air flow, and the exhaust baseline air flow are substantially equal to one another, the controller can also indicate that the intake air cleaner is not degraded. Also, because the intake air flow is substantially equal to the exhaust air flow, it can be inferred that there is no loss of air between the dP sensor and the MAF sensor as ambient air flows from the exhaust manifold through the engine components to the intake manifold, in turn indicating that there is no leak or clog in the engine components between the dP sensor and the MAF sensor.

[0120] If it is determined that there is no correlation between the intake air flow, the exhaust air flow, and the baseline air flow, at 720, the routine includes determining whether the intake air flow and the exhaust air flow are converging, but each of the intake air flow and the exhaust air flow is lower than the baseline air flow. In one example, the controller can determine whether the intake air flow is substantially equal to the exhaust air flow, but each of the intake air flow and the exhaust air flow is lower than the baseline air flow. In another example, the controller can determine whether the intake air flow is substantially equal to the exhaust air flow, but the intake air flow and the exhaust air flow are lower than the intake baseline air flow and the exhaust baseline air flow, respectively.

[0121] If it is determined that the intake air flow rate and the exhaust air flow rate are not converging, then at 721, it can be inferred that the intake air flow rate and the exhaust air flow rate are diverging. In one example, the divergence between the intake air flow rate and the exhaust air flow rate can be inferred based on the intake air flow rate being substantially different from the exhaust air flow rate. For example, the difference between the intake air flow rate and the exhaust air flow rate can be higher than 5%. The difference between the intake air flow rate and the exhaust air flow rate indicates that the entire volume of ambient air that enters the engine system through the exhaust tailpipe flows through the exhaust manifold, but the same volume of air can not flow through the intake manifold. Thus, it can be inferred that there can be a leak in the engine system between the dP sensor housed in the exhaust manifold and the MAF sensor housed in the intake manifold, and a portion of the air is lost from the flow path (between the dP sensor and the MAF sensor) through the leak as the air flows from the dP sensor to the MAF sensor. The controller can perform further diagnostics of the engine system to identify the location of the leak. In one example, the leak in the intake manifold can be confirmed based on a change in the engine air-to-fuel ratio estimated via an oxygen sensor coupled to the exhaust passage upstream of the exhaust catalyst. If the leak is confirmed to exist, then the controller can adjust the air-to-fuel ratio to compensate for the loss of air from the intake manifold. In one example, a leak in the evaporative emission control system coupled to the engine intake manifold can cause the air to be carried to the EVAP system as the air flows from the exhaust manifold to the intake manifold, in turn causing the intake air flow rate (estimated via the MAF) to be lower than the exhaust air flow rate (estimated via the dP). A canister purge valve (e.g., CPV 261 in Figure 2 ) is housed in a canister purge line (e.g., purge line 228 in Figure 2 ) of the EVAP system, and a canister vent valve (e.g., CVV 297 in Figure 2 ) is housed in a canister vent path (e.g., vent path 227 in Figure 2 ) of the EVAP system. The canister purge line couples the intake system to the canister of the EVAP system, and the canister vent path couples the canister to the atmosphere, the canister purge line being coupled to the intake manifold downstream of the MAF sensor. A leak in the CPV can cause air to flow from the intake manifold to the canister via the purge line.

[0122] If it is determined at 720 that the intake air flow rate and the exhaust air flow rate are converging but each of the intake air flow rate and the exhaust air flow rate is lower than the baseline air flow rate, then it can be inferred that there is a blockage in the air flow. It can be determined that the intake air flow rate and the exhaust air flow rate are converging but the intake air flow rate is lower than the intake baseline air flow rate and the exhaust air flow rate is lower than the baseline exhaust air flow rate. An auxiliary flow path for air can be opened to determine the location of the blockage. The method continues to as described in Figure 7BStep A as described in the Background.

[0123] At 722 (in Figure 7B As described in the Background, the method 700 includes opening the CPV and opening (or maintaining open) the CVV. The controller can send a signal to each of the actuators coupled to the CPV and the CVV to actuate each of the CPV and the CVV to an open position. When the CPV and the CVV are opened, an auxiliary path coupling the engine exhaust manifold to the atmosphere can be established through the purge line and the vent path. In one example, if the CVV was already in the open position during the diagnostic routine, the CVV can be maintained in the open position.

[0124] At 724, the method 700 includes determining whether the exhaust air flow increases to a baseline air flow after the auxiliary path to the atmosphere is opened. In one example, the controller can determine whether the exhaust air flow increases to a baseline exhaust air flow after the auxiliary path to the atmosphere is opened. If, for example, the intake air filter is not clogged after the air filter is installed, a first amount of ambient air can enter the exhaust manifold and subsequently flow to the atmosphere via the intake manifold due to the lower pressure at the exhaust manifold (created by the reverse rotation of the engine and the electric supercharger) (baseline air flow). However, if the intake air filter is clogged, the primary path of air entering the engine system through the exhaust passage (exhaust tailpipe) to escape to the atmosphere can be limited, thereby reducing the air flow through the primary path relative to the baseline air flow. If the un-limited auxiliary path to the atmosphere is opened, a higher amount of air can enter the exhaust manifold and flow to the atmosphere via the auxiliary path. For example, if the purge line and the vent path of the EVAP system provide the auxiliary path, a first amount of ambient air can enter the exhaust manifold and subsequently flow to the atmosphere via the purge line and the vent path of the EVAP system. When the purge line is coupled to the intake manifold downstream of the MAF sensor, the dP sensor can detect an increase in the air flow through the exhaust manifold, and the MAF sensor can not detect the increase.

[0125] Accordingly, if it is determined that the exhaust air flow increases to a baseline air flow (or an exhaust baseline air flow) after the CPV and the CVV are opened, it can be inferred that there is a restriction in the primary path. At 726, a diagnostic code (flag) indicating a clogging or degradation of the intake air filter can be set.

[0126] Because the intake air filter has deteriorated, less than the desired amount of air can flow into the intake manifold during subsequent engine combustion conditions, in turn causing a rich of stoichiometric air-fuel blend in the engine. To provide the desired air-fuel ratio for combustion during subsequent engine combustion conditions, the throttle opening can be adjusted based on the filter clogging at 730. In one example, the controller can increase the opening of the intake throttle to compensate for the clogging in the intake air filter before the clogged air filter is replaced.

[0127] If it is determined at 724 that the exhaust air flow has not increased to the baseline air flow (or exhaust baseline air flow) even after opening the CPV and CVV, it can be inferred that a clog can exist at a location in the exhaust or intake system of the engine other than the intake air filter. Due to the clog, a lower amount of air (relative to the amount of air flowing through the engine after the air filter is installed) can flow through the engine components even after opening the second path to atmosphere. In one example, the clog can include a foreign object in the muffler or deteriorated exhaust after the treatment device. At 732, the possible clog can be indicated by setting a diagnostic code, and the controller can perform further diagnostics of the engine system to identify the location of the clog. In one example, if the catalyst monitoring sensor (oxygen sensor) is not alternating between rich and lean, it can be inferred that the exhaust catalyst is clogged. A clog in the exhaust catalyst can decrease fuel economy and increase misfire occurrence.

[0128] In this way, the air filter can be indicated as clogged in response to an increase in exhaust air flow after opening the CPV and CVV, and the air filter can be indicated as not clogged in response to no change in exhaust air flow after opening the CPV and CVV.

[0129] At 718, the diagnostic routine is complete and each of the engine and the electric supercharger can be stopped from rotating. The controller can send a signal to the motor that powers the engine to stop rotating the engine. The controller can also send a signal to the actuator coupled to the electric supercharger to pause operation of the electric supercharger.

[0130] In this manner, during a first engine condition, the engine can be reverse-rotated without fuel, and a first baseline intake airflow and a second baseline exhaust airflow can be recorded. The first engine condition includes engine conditions where less than a first threshold duration has elapsed since the intake air filter was installed. During a second engine condition, the engine can be reverse-rotated without fuel, and updated intake airflow and updated exhaust airflow can be recorded. Deterioration of the intake air filter can be diagnosed based on the correlation between each of the first baseline intake airflow, the second baseline exhaust airflow, the updated intake airflow, and the updated exhaust airflow. The second engine condition includes engine conditions used when the intake air filter has been used for more than a second threshold duration, where the second threshold duration is longer than the first threshold duration.

[0131] Figure 8 The illustration shows the intake air filter (e.g., Figure 2 An exemplary timeline 800 for the diagnosis of the air filter 215 in the middle. The horizontal (x-axis) represents time and the vertical markings t1–t6 identify the effective time in the diagnostic routine of the intake air filter.

[0132] The first graph (line 802) shows the vehicle speed over time. The second graph (line 804) shows the engine's rotation direction. For example, during engine operation with air-fuel combustion in the engine cylinders, the engine can be rotated in the forward, default direction, supplying fuel to the engine cylinders via fuel injectors. Alternatively, the engine can be rotated in the reverse direction, for example, via a motor connected to a hybrid electric vehicle (HEV) or via a starter motor, when no fuel has been added. The third graph (line 806) shows an electric supercharger (e.g., connected downstream of the intake compressor and upstream of the charging air cooler (CAC) to a pipe in parallel with the intake manifold). Figure 1 The direction of rotation of the electric supercharger 155 in the figure. The electric supercharger can be rotated in the forward or reverse direction by reversing the circuit of the actuator connected to the electric supercharger, and the electric supercharger is powered via the on-board energy storage device. The forward rotation direction of the electric supercharger is opposite to the reverse rotation direction of the electric supercharger. The fourth graph (line 808) shows the operation of the motor connected to the hybrid electric vehicle (HEV). The motor can be operated to provide motor torque to propel the HEV. The fifth graph (line 811) shows the differential pressure sensor (e.g., ...) connected across the particulate filter contained in the exhaust manifold. Figure 2The readings of the dP sensor (263) are used. During intake air filter diagnostics, the dP sensor readings correspond to the exhaust air flow rate. The sixth graph (line 814) shows the MAF sensor (e.g., connected to the intake manifold)... Figure 2 The MAF sensor (210) reading is used. During intake air filter diagnostics, the MAF sensor reading corresponds to the intake airflow rate. The seventh graph (line 818) shows the opening of the canister flush valve (CPV) connected to the canister flush line of the evaporative emission control system. The canister flush line connects the intake duct (downstream of the MAF sensor) to the canister of the EVAP system. Additionally, the canister vent path, which houses the canister vent valve (CVV), connects the canister to the atmosphere. If either the CPV or the CVV is open, a flow path is established between the intake manifold and the atmosphere via the canister flush line and the canister vent path. The eighth graph (dashed line 820) shows flags indicating diagnostic codes set to indicate a deteriorated exhaust tuning valve.

[0133] Before time t0, a new (unused) intake air filter is installed in the vehicle's intake manifold at the manufacturing facility. After the air filter is installed, a baseline airflow is estimated between times t0 and t1, when the vehicle is not being propelled by engine torque or motor torque and optionally after confirming that the vehicle is not occupied based on input from an onboard camera. At time t1, the controller sends a signal to the HEV motor to cause the engine to rotate in the reverse direction at a first engine speed without fuel. Furthermore, the controller sends a signal to the actuator coupled to the electric supercharger to cause the electric supercharger to rotate in the reverse direction at a first electric supercharger speed. As the engine and electric supercharger rotate in their respective reverse directions, a lower pressure is generated at the engine exhaust manifold, and ambient air enters the engine system via the exhaust manifold. The ambient air then flows through the engine cylinders, the intake manifold, and is subsequently delivered to the atmosphere via the intake manifold. During the baseline airflow measurement, the CPV valve is kept in the closed position. Between times t0 and t1, the intake airflow estimated via the MAF sensor (shown by line 810) is stored in the vehicle database, with the baseline airflow corresponding to an unused (unclogged) air filter. This baseline airflow 810 is later used during intake air filter diagnostics. Because no intake air filter degradation is indicated, the flag is kept in the off position.

[0134] At time tl, once the baseline air flow is saved in memory, the controller sends a signal to each of the HEV motor and electric supercharger actuators to suspend operation and stop rotating the engine and electric supercharger (for the purposes of the diagnostic routine). The duration between times tl and t2 corresponds to a threshold duration of time after which a diagnostic routine of the intake air filter will need to be performed in a timely manner. The duration between times tl and t2 includes multiple drive cycles and periods of time while the vehicle is not operating (not being propelled via engine torque or motor torque).

[0135] At time t2, the vehicle is started from rest and is operating via engine torque. The engine is driven by combustion and is rotating in the forward direction. The electric supercharger is rotating in the forward direction to provide the desired boost pressure based on torque demand. The HEV motor is not operating for engine rotation or vehicle propulsion. Between times t2 and t3, the MAF reading represents the amount of air entering the engine for combustion via the intake tract. The amount of air entering the intake tract is proportional to the throttle opening. The dP sensor reading corresponds to the soot load accumulated on the particulate filter across which the dP sensor is coupled. Between t2 and t3, the particulate filter is regenerated. During particulate filter regeneration, hot combustion from the exhaust burns the soot deposited on the particulate filter, and as the soot load on the particulate filter decreases, a corresponding decrease in differential pressure across the particulate filter is observed.

[0136] At time t3, the vehicle speed is reduced to zero and between times t3 and t4, the vehicle is no longer being operated using engine torque and / or motor torque (vehicle cut-off condition begins). Accordingly, at time t3, the engine is shut down by suspending fuel injection and spark to the engine cylinders. Also, the operation of the electric supercharger is suspended. Between times t3 and t4, the engine is maintained in a shut down condition.

[0137] At time t4, after a threshold duration has elapsed since the vehicle was turned off at time t3 and optionally after confirming that the vehicle is unoccupied based on input from the onboard camera, a diagnostic of the intake air filter is initiated by the wake-up controller. The controller sends a signal to the HEV motor to cause the engine to turn in a reverse direction at a first engine speed without fueling. Also, the controller sends a signal to an actuator coupled to the electric supercharger to cause the electric supercharger to spin in a reverse direction at a first electric supercharger speed. When the engine and electric supercharger are spinning in their respective reverse directions, a lower pressure is created at the engine exhaust manifold and ambient air can enter the engine system via the exhaust passage. Between times t4 and t5, ambient air flows through the exhaust manifold, engine cylinders, and intake manifold (in that order). The baseline air flow 813 estimated between times to and ti is retrieved from the onboard database and compared to each of the intake air flow estimated based on MAF readings and the exhaust air flow estimated based on dP sensor readings.

[0138] Between times t4 and t5, it is observed that the intake air flow is equal to the exhaust air flow, but each of the intake air flow and exhaust air flow is lower than the baseline air flow 813. Thus, it is inferred that an equal amount of air is flowing through the exhaust manifold and intake manifold, but due to a clog in the engine system, the amount of air entering the engine system during this time is lower compared to the amount of air entering the engine after the intake air filter was installed (between times to and ti).

[0139] At time t5, the controller sends a signal to the CPV to actuate the valve to an open position. The CVV is also maintained in an open position to establish fluid communication between the intake manifold and atmosphere via the canister purge line and canister vent path. After opening the CPV, between times t5 and t6, it is observed that the dP sensor reading is increasing while the MAF sensor reading does not change by any significant amount (more than 5%). The increasing exhaust air flow is equal to the baseline air flow 813. Based on the increase in exhaust air flow relative to the baseline air flow, it is inferred that there is a clog in the intake air filter and because the unobstructed flow path to atmosphere via the canister purge line and canister vent path is opened, there is an increase in the air flow entering the exhaust manifold.

[0140] In response to detecting a clog in the intake air filter, a flag is set after time t5 to notify the operator. At time t6, at the end of the diagnostic routine, the controller sends a signal to each of the HEV motor and electric supercharger actuators to suspend operation and stop rotating the engine and electric supercharger, respectively. Also, the CPV is actuated to the closed position to seal the EVAP system. After time t6, no engine torque and / or motor torque is used to propel the vehicle, and the engine is maintained in the off condition until the vehicle key is subsequently turned on. The flag indicating the intake air filter clog (deterioration) is maintained until the air filter is replaced or serviced.

[0141] In this way, existing engine components such as the differential pressure sensor and MAF sensor can be repurposed as exhaust air flow meters and intake flow meters, respectively, for diagnosing the intake air filter. The technical effect of confirming a clog in the intake air filter by opening an auxiliary path to atmosphere via the EVAP system is that a clog in the intake air filter can be distinguished from clogs in other intake and exhaust components such as the exhaust catalyst. By detecting deterioration of the intake air filter, the desired air-fuel ratio can be adjusted and combustion of a richer air-fuel blend can be reduced. Overall, by monitoring the health of the intake air filter in a timely manner, deterioration of the air filter can be detected in time, and a clogged intake air filter can be replaced immediately.

[0142] An example engine method includes indicating a clogged intake air filter during a run-on start of an engine in an unfueled condition when the engine is turned in a reverse direction based on an air flow through an exhaust system relative to an air flow through an intake system and further based on a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere. In any of the foregoing examples, additionally or optionally, indicating the clogged intake air filter based on the air flow through the exhaust system relative to the air flow through the intake system includes comparing the air flow through the exhaust system and the air flow through the intake system to each other and to a baseline air flow, indicating an air flow clog in response to the air flow through the exhaust system being substantially equal to the air flow through the intake system and each of the air flow through the exhaust system and the air flow through the intake system being lower than the baseline air flow, and indicating the air flow clog to be a clogged intake air filter based on a change in the air flow through the exhaust system after opening the auxiliary path to atmosphere. In any or all of the foregoing examples, additionally or optionally, the air flow through the exhaust system is estimated via a differential pressure (dP) sensor coupled across a particulate filter housed in an exhaust passage, and the air flow through the intake system is estimated via a manifold air flow (MAF) sensor coupled to an intake manifold. In any or all of the foregoing examples, additionally or optionally, indicating the air flow clog to be a clogged air filter based on the change in the air flow through the exhaust system after opening the auxiliary path to atmosphere includes indicating the air flow clog to be a clogged air filter in response to an increase in the air flow through the exhaust system after opening each of a compressor purge valve (CPV) and a compressor vent valve (CVV) of an evaporative emission control (EVAP) system. In any or all of the foregoing examples, additionally or optionally, the CPV is housed in a canister purge line of the EVAP system and the CVV is housed in a canister vent path of the EVAP system, the canister purge line couples the intake system to a canister of the EVAP system and the canister vent path couples the canister to atmosphere, and wherein the canister purge line is coupled to the intake manifold downstream of the MAF sensor. In any or all of the foregoing examples, the method further includes, additionally or optionally, indicating the air flow clog to be a clog in the exhaust system in response to the change in the air flow through the exhaust system after opening the auxiliary path to atmosphere being less than a threshold change in response to opening each of the CPV and the CVV. In any or all of the foregoing examples, the method further includes, additionally or optionally, indicating a leak in at least one of the intake system and the exhaust system in response to the air flow through the exhaust system being substantially different from the air flow through the intake system, wherein the leak is upstream of the dP sensor.In any or all of the foregoing examples, the method further includes, additionally or optionally, operating the intake electric supercharger in the reverse direction to carry ambient air from the engine exhaust tract to the engine intake manifold via the one or more engine cylinders while the engine is rotated in the reverse direction. In any or all of the foregoing examples, additionally or optionally, the rotational starting of the engine without fueling while the engine is rotated in the reverse direction is carried out under a predetermined set of conditions including engine speed, duration of engine rotational starting, intake throttle position, electric supercharger speed, and exhaust tuning valve position. In any or all of the foregoing examples, additionally or optionally, a baseline air flow is estimated via the MAF sensor by rotational starting of the engine without fueling in the reverse direction under the predetermined set of conditions after installation of the air filter. In any or all of the foregoing examples, additionally or optionally, the engine is coupled in a vehicle, and the reverse rotation of the engine is performed via a motor powered by a battery under conditions in which the vehicle is unoccupied and the vehicle is not in motion. In any or all of the foregoing examples, the method further includes, additionally or optionally, in response to detecting a clogged intake air filter, setting a diagnostic code, and adjusting an opening of the intake throttle to compensate for the clogging in the intake air filter.

[0143] Another engine example method for an autonomous vehicle includes, during a first engine operating condition when operating the vehicle without a human driver and when not propelling the vehicle by engine torque, causing the engine to reverse rotate without fueling and recording a first baseline intake air flow and a second baseline exhaust air flow, during a second engine operating condition when operating the vehicle without a human driver and when not propelling the vehicle by engine torque, causing the engine to reverse rotate without fueling and recording an updated intake air flow and an updated exhaust air flow, and diagnosing whether there is degradation of an intake air filter based on a correlation between each of the first baseline intake air flow, the second baseline exhaust air flow, the updated intake air flow, and the updated exhaust air flow. In any of the foregoing examples, additionally or optionally, the first engine condition includes an engine condition when less than a first threshold duration of time has elapsed since an intake air filter was installed, and the second engine condition includes a used engine condition when the intake air filter has been used for more than a second threshold duration of time, the second threshold duration of time being longer than the first threshold duration of time. In any or all of the foregoing examples, additionally or optionally, diagnosing the presence of degradation of the intake air filter is based on the updated intake air flow being substantially equal to the updated exhaust air flow, the updated intake air flow being lower than the first baseline intake air flow, and the updated exhaust air flow being lower than the first baseline exhaust air flow, and the presence of degradation of the intake air filter is further based on an increase in the updated exhaust air flow after opening an air flow path from downstream of the MAF sensor to atmosphere. In any or all of the foregoing examples, additionally or optionally, the air flow path from downstream of the MAF sensor to atmosphere is via a canister purge line, a canister, and a canister vent path of an evaporative emissions system, and wherein the air flow path is opened by actuating each of a canister purge valve coupled to the canister purge line to an open position and a canister vent valve coupled to the canister vent path to an open position. In any or all of the foregoing examples, additionally or optionally, diagnosing the absence of degradation of the intake air filter is based on the updated intake air flow being substantially equal to the updated exhaust air flow, the updated intake air flow being substantially equal to the first baseline intake air flow, and the updated exhaust air flow being substantially equal to the first baseline exhaust air flow.

[0144] In another example, a system for a hybrid vehicle includes: a vehicle; an engine; an electric machine coupled to a battery, the electric machine capable of rotating the engine; an intake tract including an intake air filter and a compressor; an exhaust tract including a particulate filter; a manifold air flow (MAF) sensor coupled to the intake tract; a differential pressure sensor coupled across the particulate filter; a canister purge line and a vent path coupling the intake tract to atmosphere via a canister, the canister purge line including a canister purge valve (CPV) and the vent path including a canister vent valve (CVV). The hybrid vehicle further includes a controller having computer readable instructions stored on a non-transitory memory for: obtaining a baseline air flow via the MAF sensor by using the electric machine to reverse rotate the engine when the intake air filter is first installed; and after using the intake air filter since installation of the intake air filter for a threshold duration and while the engine is rotated in reverse by the electric machine, obtaining a first intake air flow via the MAF sensor and a first exhaust air flow via the differential pressure sensor, comparing the first intake air flow, the first exhaust air flow, and the baseline air flow, and in response to the first intake air flow and the first exhaust air flow being equal to each other and lower than the baseline air flow, diagnosing the intake air filter in response to a change in the first exhaust air flow after the CPV and CVV are opened. In any of the foregoing examples, additionally or optionally, diagnosing the intake air filter in response to a change in the first exhaust air flow includes one of: indicating that the air filter is clogged in response to an increase in the first exhaust air flow after the CPV and CVV are opened; indicating that the air filter is not clogged in response to the first exhaust air flow not changing after the CPV and CVV are opened. In any or all of the foregoing examples, additionally or optionally, each of the baseline air flow, the first intake air flow, and the first exhaust air flow is measured at an engine idle for a threshold duration when the vehicle is not occupied and the vehicle is not propelled.

[0145] It should be noted that the example control and estimation routines included herein can be employed in a variety of engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by control systems comprising a combination of a controller and various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and so on. As such, various acts, operations, and / or functions illustrated can be implemented in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing can be rearranged from that described. Also, various acts or functions can be added as an output to the processing, or practiced as part of a routine. Further, not all of the acts or functions described need to be performed. It is possible for a variety of these acts or functions to be performed by the same device, or by different devices depending upon the circumstances. Also, the description can use "processing" or "processing means" to represent one or more devices configured and / or programmed to perform a certain action. The one or more devices actually performing the action need not be specifically designated as the "processor" or "processing means," unless required to understand the novelty in context.

[0146] It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not intended to suggest any limitation as to the scope of use or functionality, as many variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or properties.

[0147] The appended claims particularly point out the certain combinations and sub-combinations that are regarded as novel and non-obvious. These claims can refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood as including one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties can be claimed through amendment of the present claims or presentation of additional claims in this or a related application. Such amended or additional claims, whether they are broader, narrower, equal, or different in scope to the original claims, are also regarded as included within the subject matter of the present disclosure.

[0148] According to the invention, an engine method includes, during a run-up start of the engine with no fuel on board when the engine is turned in reverse, indicating a clogged air intake filter based on an air flow through an exhaust system relative to an air flow through an intake system and further based on a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere.

[0149] According to embodiments, the features of the present invention are further characterized by indicating the clogged intake air filter based on the air flow through the exhaust system relative to the air flow through the intake system includes comparing the air flow through the exhaust system and the air flow through the intake system to each other and to a baseline air flow, indicating an air flow clog responsive to the air flow through the exhaust system being substantially equal to the air flow through the intake system and each of the air flow through the exhaust system and the air flow through the intake system being lower than the baseline air flow, and indicating the air flow clog is a clogged intake air filter based on a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere.

[0150] According to embodiments, the air flow through the exhaust system is estimated via a differential pressure (dP) sensor coupled across a particulate filter housed in the exhaust passage, and the air flow through the intake system is estimated via a manifold air flow (MAF) sensor coupled to an intake manifold.

[0151] According to embodiments, indicating the air flow clog is a clogged air filter based on a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere includes indicating the air flow clog is a clogged air filter responsive to an increase in the air flow through the exhaust system after opening each of a compressor purge valve (CPV) and a compressor vent valve (CVV) of an evaporative emission control (EVAP) system.

[0152] According to embodiments, the CPV is housed in a canister purge line of the EVAP system and the CVV is housed in a canister vent path of the EVAP system, the canister purge line couples an intake system to a canister of the EVAP system and the canister vent path couples the canister to atmosphere, and wherein the canister purge line is coupled to an intake manifold downstream of the MAF sensor.

[0153] According to embodiments, the features of the present invention are further characterized by indicating the air flow clog is a clog in the exhaust system responsive to a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere being less than a threshold change responsive to opening each of the CPV and the CVV.

[0154] According to embodiments, indicating a leak in at least one of the intake system and the exhaust system responsive to the air flow through the exhaust system being substantially different than the air flow through the intake system, wherein the leak is upstream of the dP sensor.

[0155] According to embodiments, the intake electric supercharger is operated in the reverse direction to carry ambient air from the engine exhaust tract to the engine intake manifold via one or more engine cylinders when the engine is rotated in the reverse direction.

[0156] According to embodiments, the engine is cranked without fueling while the engine is rotated in the reverse direction under a predetermined set of conditions including engine speed, duration of engine cranking, intake throttle position, electric supercharger speed, and exhaust tuning valve position.

[0157] According to embodiments, a baseline air flow is estimated via the MAF sensor by cranking the engine without fueling in the reverse direction under the predetermined set of conditions after an air filter is installed.

[0158] According to embodiments, the engine is coupled in a vehicle, and the reverse rotation of the engine is performed via a motor powered by a battery under conditions in which the vehicle is unoccupied and the vehicle is not in motion.

[0159] According to embodiments, in response to detecting a clogged intake air filter, a diagnostic code is set, and an opening of an intake throttle is adjusted to compensate for the clogging in the intake air filter.

[0160] According to the present invention, an engine method for an autonomous vehicle includes, during a first engine operating condition when the vehicle is operated without a human driver and when the vehicle is not propelled by engine torque, rotating the engine in reverse without fueling and recording a first baseline intake air flow and a second baseline exhaust air flow, during a second engine operating condition when the vehicle is operated without a human driver and when the vehicle is not propelled by engine torque, rotating the engine in reverse without fueling and recording an updated intake air flow and an updated exhaust air flow, and diagnosing whether an intake air filter is deteriorating based on a correlation between each of the first baseline intake air flow, the second baseline exhaust air flow, the updated intake air flow, and the updated exhaust air flow.

[0161] According to embodiments, the first engine condition includes an engine condition when less than a first threshold duration of time has elapsed since an intake air filter was installed, and the second engine condition includes a used engine condition when the intake air filter has been used for more than a second threshold duration of time, the second threshold duration of time being longer than the first threshold duration of time.

[0162] According to an embodiment, diagnosing the presence of degradation of the intake air filter is based on the updated intake air flow rate being substantially equal to the updated exhaust air flow rate, the updated intake air flow rate being lower than the first baseline intake air flow rate, and the updated exhaust air flow rate being lower than the first baseline exhaust air flow rate, and the presence of degradation of the intake air filter is further based on an increase in the updated exhaust air flow rate after opening an air flow path from downstream of the MAF sensor to atmosphere.

[0163] According to an embodiment, the application further features that the air flow path from downstream of the MAF sensor to atmosphere is via a canister purge line, a canister, and a canister vent path of an evaporative emissions system, and wherein the air flow path is opened by actuating each of a canister purge valve coupled to the canister purge line to an open position and a canister vent valve coupled to the canister vent path to an open position.

[0164] According to an embodiment, the application further features that diagnosing the absence of degradation of the intake air filter is based on the updated intake air flow rate being substantially equal to the updated exhaust air flow rate, the updated intake air flow rate being substantially equal to the first baseline intake air flow rate, and the updated exhaust air flow rate being substantially equal to the first baseline exhaust air flow rate.

[0165] According to the present invention, a hybrid vehicle system is provided, the hybrid vehicle having: a vehicle; an engine; an electric motor coupled to a battery, the electric motor capable of rotating the engine; an intake tract including an intake air filter and a compressor; an exhaust tract including a particulate filter; a manifold air flow (MAF) sensor coupled to the intake tract; a differential pressure sensor coupled across the particulate filter; a canister purge line and a breather path coupling the intake tract to atmosphere via a canister, the canister purge line including a canister purge valve (CPV) and the breather path including a canister breather valve (CVV); and a controller having computer readable instructions stored on a non-transitory memory for: obtaining a baseline air flow via the MAF sensor by using the electric motor to reverse rotate the engine when the intake air filter is first installed; and after using the intake air filter since installation of the intake air filter for a threshold duration and while the engine is rotated in reverse by the electric motor, obtaining a first intake air flow via the MAF sensor and a first exhaust air flow via the differential pressure sensor, comparing the first intake air flow, the first exhaust air flow, and the baseline air flow, and in response to the first intake air flow and the first exhaust air flow being equal to each other and lower than the baseline air flow, diagnosing the intake air filter in response to a change in the first exhaust air flow after the CPV and CVV are opened.

[0166] According to embodiments, diagnosing the intake air filter in response to a change in the first exhaust air flow includes one of: indicating that the air filter is clogged in response to an increase in the first exhaust air flow after the CPV and CVV are opened; indicating that the air filter is not clogged in response to the first exhaust air flow not changing after the CPV and CVV are opened.

[0167] According to embodiments, each of the baseline air flow, the first intake air flow, and the first exhaust air flow is measured at an engine idle for a threshold duration when the vehicle is not occupied and the vehicle is not propelled.

Claims

1. An engine method comprising: during a run-on of an engine without fueling while the engine is being turned in a reverse direction via a motor, comparing an air flow through an intake system and an air flow through an exhaust system to each other and to a baseline air flow; in response to the air flow through the exhaust system being substantially equal to the air flow through the intake system and each of the air flow through the exhaust system and the air flow through the intake system being lower than the baseline air flow, indicating an air flow blockage; and based on a change in the air flow through the exhaust system after opening an auxiliary path to atmosphere that couples the intake system to atmosphere through a canister purge line and a vent path, indicating that the air flow blockage is a blocked intake air filter.

2. The method of claim 1, wherein the air flow through the exhaust system is estimated via a differential pressure sensor, dP sensor, coupled across a particulate filter housed in an exhaust runner, and the air flow through the intake system is estimated via a manifold air flow sensor, MAF sensor, coupled to an intake manifold.

3. The method of claim 1, wherein indicating that the air flow blockage is the clogged intake air filter based on the change in the air flow through the exhaust system after opening the secondary path to atmosphere comprises: in response to an increase in the air flow through the exhaust system after opening each of a compressor purge valve, CPV, and a compressor vent valve, CVV, of an evaporative emission control system, EVAP system, indicating that the air flow blockage is the blocked intake air filter.

4. The method of claim 3, wherein the CPV is housed in a canister purge line of the EVAP system that couples the intake system to a canister of the EVAP system and the CVV is housed in a canister vent path of the EVAP system that couples the canister to atmosphere, and wherein the canister purge line is coupled to an intake manifold downstream of a manifold air flow sensor, MAF sensor, coupled to the intake manifold.

5. The method of claim 3, further comprising: in response to the change in the air flow through the exhaust system after opening the auxiliary path to atmosphere being less than a threshold change in response to opening each of the CPV and the CVV, indicating that the air flow blockage is a blockage in the exhaust system.

6. The method of claim 2, further comprising: in response to the air flow through the exhaust system being different than the air flow through the intake system, indicating a leak in at least one of the intake system and the exhaust system, wherein the leak is upstream of the dP sensor.

7. The method of claim 1, further comprising, when turning the engine in a reverse direction, operating an intake electric supercharger in a reverse direction to carry ambient air from an engine exhaust runner through one or more engine cylinders to the engine intake manifold.

8. The method of claim 2, wherein the rotating start of the engine without fueling while rotating the engine in the reverse direction is performed under a predetermined set of conditions, the predetermined set of conditions including engine speed, duration of engine rotation start, intake air throttle position, electric supercharger speed, and exhaust tuning valve position.

9. The method of claim 8, wherein the baseline air flow is estimated via the MAF sensor by rotating starting the engine without fueling in the reverse direction under the predetermined set of conditions after installing the intake air filter.

10. The method of claim 1, wherein the engine is coupled in a vehicle, and the reverse rotation of the engine is performed via a motor powered by a battery under conditions in which the vehicle is unoccupied and the vehicle is not in motion.

11. The method of claim 1, further comprising: in response to detecting the clogged intake air filter, setting a diagnostic code, and adjusting an intake throttle opening to compensate for the clogging in the intake air filter.

12. A hybrid vehicle system, the hybrid vehicle system comprising: a vehicle; an engine; an electric motor coupled to a battery, the electric motor capable of rotating the engine; an intake passage including an intake air filter and a compressor; an exhaust passage including a particulate filter; a manifold air flow (MAF) sensor coupled to the intake passage; a differential pressure sensor coupled across the particulate filter; a canister purge line and a breather path coupling the intake passage to atmosphere via a canister, the canister purge line including a canister purge valve (CPV) and the breather path including a canister vent valve (CVV); and a controller having computer readable instructions stored on a non-transitory memory for: obtaining a baseline air flow via the MAF sensor by reverse rotating the engine using the electric motor when the intake air filter is first installed; and after using the intake air filter for a threshold duration since the intake air filter was installed and while rotating the engine in reverse by the electric motor, obtaining a first intake air flow via the MAF sensor and a first exhaust air flow via the differential pressure sensor, comparing the first intake air flow, the first exhaust air flow, and the baseline air flow; and in response to the first intake air flow and the first exhaust air flow being equal to each other and lower than the baseline air flow, diagnosing the intake air filter in response to a change in the first exhaust air flow after opening the CPV and the CVV.

13. The system of claim 12, wherein diagnosing the intake air filter in response to the change in the first exhaust air flow comprises one of: indicating that the intake air filter is clogged in response to an increase in the first exhaust air flow after the opening of the CPV and the CVV; and indicating that the intake air filter is not clogged in response to the first exhaust air flow not changing after the opening of the CPV and the CVV.

14. The system of claim 12, wherein each of the baseline air flow, the first intake air flow, and the first exhaust air flow is measured at an engine idle for a threshold duration when the vehicle is unoccupied and the vehicle is not propelled.

Images