Method and system for diagnosing a particulate filter sensor

Abstract

The present disclosure relates to methods and systems for diagnosing a particulate filter sensor. Systems and methods are presented for diagnosing operation of a sensor of an exhaust system. In one example, the systems and methods can diagnose operation of the sensor while the engine is combusting air and fuel. Further, operation of the sensor can be diagnosed while the engine is not combusting air and fuel, such that vehicle occupants are not disturbed by the diagnosis.

Description

Technical Field

[0001] This application relates to methods and systems for determining the presence or absence of degradation in a differential pressure sensor that senses pressure changes across a gasoline particulate filter. These methods and systems are particularly useful for direct fuel injection engines that can operate intermittently in stratified charge mode. Background Technology

[0002] Gasoline / petrol spark-ignition engines may include direct fuel injection. Fuel can be injected directly into the engine cylinders, allowing the vaporization of the injected fuel to cool the charge within the cylinders. Compared to port-injected engines, this allows the engine to operate at higher loads before engine knock occurs, by cooling the cylinder charge. Therefore, the engine can operate more efficiently and provide more power than port-injected engines. However, direct fuel injection into the cylinders also provides an opportunity for the injected fuel to stratify within the cylinders, resulting in carbonaceous exhaust. This carbonaceous exhaust can be stored in a particulate filter, where it can then be oxidized, reducing the amount of particulate matter released into the atmosphere. Over time, the particulate filter can become clogged with carbonaceous soot, potentially requiring regeneration. One way to determine if the particulate filter is clogged with more than a threshold amount of carbonaceous soot is to measure the pressure change, or differential pressure, across the particulate filter. If the particulate filter is clogged with carbonaceous soot, a higher differential pressure will be indicated when the engine airflow is high. However, due to maintenance or unforeseen circumstances, the hose of a differential pressure sensor may detach from its anchoring position. If the hose of a differential pressure sensor detaches, it becomes difficult to determine whether the differential pressure sensor is providing reliable information. Therefore, a method for determining the reliability of differential pressure sensor data is desirable. Summary of the Invention

[0003] The inventors have recognized the above-mentioned problems and have developed a vehicle operation method comprising: in response to an exhaust system sensor diagnostic request, rotating the engine in the areverse direction without adding fuel to the engine; receiving data from a differential pressure sensor to a controller while rotating the engine in the areverse direction; and adjusting engine operation via the controller in response to the data from the differential pressure sensor.

[0004] Compared to rotating the engine forward when it is not burning air and fuel, rotating the engine in the reverse direction when it is not burning air and fuel may provide a greater flow rate through the engine, thus improving the signal-to-noise ratio of the exhaust sensor output. Furthermore, by rotating the engine without combustion, exhaust sensor diagnostics can be performed when there is no vehicle occupant, making the diagnostics less likely to be detected. Moreover, exhaust sensor diagnostics can be selectively performed during engine operation when they are unlikely to be detected.

[0005] This specification offers several advantages. For example, the method allows for improved sensor diagnostics. Additionally, the method provides diagnostics whether the engine is operating or not, enabling timely diagnosis of the exhaust sensor. Furthermore, the method provides an improved signal-to-noise ratio for the exhaust sensor output.

[0006] The advantages and other advantages and features described above will become more apparent when viewed alone with reference to the detailed embodiments below or in conjunction with the accompanying drawings.

[0007] It should be understood that the foregoing summary is provided as a simplified description of the concepts further described in the detailed embodiments. This does not imply confirmation of the key or essential characteristics of the claimed subject matter, the scope of which is uniquely defined by the appended claims. Furthermore, the claimed subject matter is not limited to embodiments that address any of the deficiencies described above or in any part of this disclosure. Attached Figure Description

[0008] The advantages described herein will be more fully understood by reading, alone or with reference to, the examples referred to herein as specific embodiments, in which:

[0009] Figure 1 This is a schematic diagram of an engine;

[0010] Figure 2 It includes Figure 1 A schematic diagram of the powertrain of a hybrid vehicle with an engine;

[0011] Figure 3A and Figure 3B Example engine valve timing is shown;

[0012] Figure 4 The diagram is based on Figures 5A-5C The method uses a graph of vehicle operation during exhaust sensor diagnostics; and

[0013] Figures 5A-5C An example method for diagnosing exhaust system sensors is shown. Detailed Implementation

[0014] This specification relates to the operation of a diagnostic differential pressure sensor that senses pressure on the opposite side of a particulate filter. The particulate filter may be incorporated with, for example, […]. Figure 1 In the vehicle shown, the spark-ignition engine is used. The engine can be as follows: Figure 2 A portion of the hybrid vehicle shown. Figure 3A and Figure 3B As shown, when the engine is rotated in the reverse direction, the engine can also have timing on the intake and exhaust valves that provide a higher flow rate through the engine. According to... Figures 5A-5C The method allows vehicles to... Figure 4 The operation is shown.

[0015] Reference Figure 1 Including multiple cylinders ( Figure 1 An internal combustion engine 10 (shown as one of its cylinders) is controlled by an electronic engine controller 12. The engine 10 comprises a cylinder head 35 and a cylinder block 33, which include a combustion chamber 30 and cylinder walls 32. A piston 36 is positioned therein and reciprocates via a connection to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 (e.g., a low-voltage (operating at less than 30 volts) electric motor) includes a pinion shaft 98 and a pinion 95. The pinion shaft 98 selectively advances the pinion 95 to engage the ring gear 99. The starter 96 can be mounted directly to the front or rear of the engine. The starter 96 can rotate the engine 10 in either forward or reverse directions. In some examples, the starter 96 can selectively supply torque to the crankshaft 40 via a belt or chain. In one example, the starter 96 is in a basic state when not engaged with the engine crankshaft. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via corresponding intake valve 52 and exhaust valve 54. Each intake valve and exhaust valve can be operated by intake cam 51 and exhaust cam 53. The position of intake cam 51 can be determined by intake cam sensor 55. The position of exhaust cam 53 can be determined by exhaust cam sensor 57. Intake valve 52 can be selectively activated and deactivated by valve actuation device 59. Exhaust valve 54 can be selectively activated and deactivated by valve actuation device 58. Valve actuation devices 58 and 59 can be hydraulic and / or electromechanical devices.

[0016] Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30 in a direct injection manner known to those skilled in the art. Fuel injector 66 delivers liquid fuel in proportion to the pulse width from controller 12. Fuel is delivered to fuel injector 66 via a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). In one example, a high-pressure two-stage fuel system may be used to generate higher fuel pressures.

[0017] Additionally, the intake manifold 44 is shown communicating with the engine intake port 42. An optional electronic throttle valve 62 adjusts the position of the throttle plate 64 to control the airflow from the intake port 42 to the intake manifold 44. In some examples, the throttle valve 62 and the throttle plate 64 may be positioned between the intake valve 52 and the intake manifold 44, such that the throttle valve 62 is an intake duct throttle valve. An air filter 43 cleans the air entering the engine intake port 42.

[0018] In response to controller 12, distributorless ignition system 88 provides ignition spark to combustion chamber 30 via spark plug 92. Universal exhaust oxygen (UEGO) sensor 126 is shown as being coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, dual-state exhaust oxygen sensor may replace UEGO sensor 126. In one example, converter 70 may include multiple catalyst blocks. In another example, multiple emission control units may be used, each with multiple blocks. In one example, converter 70 may be a three-way catalytic converter. When engine 10 rotates forward to burn air and fuel, exhaust flows in the direction from exhaust valve 54 to muffler 72. Depending on the direction of exhaust flow, particulate filter 71 is located downstream of converter 70. Differential pressure sensor 38 senses the pressure difference from front 71A to rear 71B of particulate filter 71. Specifically, depending on the direction of exhaust flow, upstream port 38A senses the pressure upstream of particulate filter 71 via hose 38C, and downstream port 38B senses the pressure downstream of particulate filter 71 via hose 38D. The muffler 72 is positioned downstream of the particulate filter 71 and includes an exhaust valve 73 for selectively bypassing the noise control medium 80. When the exhaust valve 73 is open, it allows exhaust gas to flow directly to the atmosphere via outlet 74. When the exhaust valve 73 is closed, it directs exhaust gas through the noise control medium 80 and outlet 75.

[0019] Controller 12 in Figure 1The computer is shown as a conventional microcomputer, which includes: a microprocessor unit (CPU) 102, an input / output port (I / O) 104, a read-only memory (ROM) 106 (e.g., non-transitory memory), a random access memory (RAM) 108, a keep-alive memory (KAM) 110, and a conventional data bus. The controller 12 is shown receiving various signals from sensors connected to the engine 10, including, in addition to those previously discussed, the following: engine coolant temperature (ECT) from temperature sensor 112 connected to cooling sleeve 114; position sensor 134 connected to accelerator pedal 130 for sensing the force applied by foot 132; position sensor 154 connected to brake pedal 150 for sensing the force applied by foot 152; engine manifold pressure (MAP) measurement from pressure sensor 121 connected to intake manifold 144; engine position sensor from Hall effect sensor 118 for sensing crankshaft 40 position; measurement of air mass entering the engine from sensor 120; and throttle position measurement from sensor 68. Atmospheric pressure may also be sensed (sensor not shown) for processing by the controller 12. In a preferred aspect of this specification, the engine position sensor 118 generates a predetermined number of equidistant pulses for each crankshaft rotation (the crankshaft rotation determines the engine speed (RPM)).

[0020] During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, typically, exhaust valve 54 is closed and intake valve 52 is open. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. Piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its maximum volume) is typically referred to by those skilled in the art as bottom dead center (BDC).

[0021] During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its minimum volume) is generally referred to by those skilled in the art as top dead center (TDC). Fuel is introduced into the combustion chamber during what is hereinafter referred to as injection. The injected fuel is ignited by a known ignition means (e.g., spark plug 92) during what is hereinafter referred to as ignition, resulting in combustion.

[0022] During the expansion stroke, the expanding gas pushes piston 36 back to the BDC. Crankshaft 40 converts the piston motion into rotational torque on the rotating shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48 and the piston returns to the TDC. Note that the above is only shown as an example, and the opening and / or closing timing of the intake and exhaust valves can be varied. For example, positive or negative valve overlap, intake valve closing delay, or many other examples may be provided.

[0023] Figure 2 It is a block diagram of vehicle 225 including transmission system 200. Figure 2 The transmission system includes Figure 1 The engine 10 is shown. The transmission system 200 can be powered by the engine 10. The engine 10 can utilize... Figure 1 The engine starting system shown is started, either by a starter / generator (DISG) 240 integrated into the drivetrain. The DISG 240 (e.g., a high-voltage (operating at a voltage greater than 30 volts) electric motor) may also be referred to as an electric motor, generator, and / or generator. The DISG 240 can rotate the engine in a forward (e.g., clockwise when viewed from the front of engine 10) or reverse (e.g., counterclockwise when viewed from the front of engine 10) direction. Furthermore, the torque of engine 10 can be adjusted via torque actuator 204 (e.g., fuel injectors, throttle valve, etc.).

[0024] Engine output torque can be transmitted from the rear 294 of engine 10 to the input side of transmission-disengaged clutch 236 via dual-mass flywheel 215. Disengaged clutch 236 can be electrically or hydraulically actuated. In this example, disengaged clutch 236 can be operated by fluid supplied by a mechanically driven transmission fluid pump 295 or an electrically driven transmission fluid pump 299. The downstream side of disengaged clutch 236 is shown as mechanically coupled to DISG input shaft 237.

[0025] DISG 240 can be operated to provide torque to drivetrain 200 or to convert drivetrain torque into electrical energy for storage in energy storage device 275. DISG 240 has a higher torque capacity than... Figure 1The starter 96 shown has a higher output torque capacity. Furthermore, the DISG 240 directly drives or is directly driven by the drivetrain 200. No belt, gear, or chain connects the DISG 240 to the drivetrain 200. Instead, the DISG 240 rotates at the same rate as the drivetrain 200. The energy storage device 275 (e.g., a high-voltage battery or power source) can be a battery, capacitor, or inductor. The downstream side of the DISG 240 is mechanically coupled to the impeller 285 of the torque converter 206 via shaft 241. The upstream side of the DISG 240 is mechanically coupled to a disengaged clutch 236.

[0026] The torque converter 206 includes a turbine 286 to output torque to an input shaft 270. The input shaft 270 mechanically connects the torque converter 206 to an automatic transmission 208. The torque converter 206 also includes a torque converter bypass lock-up clutch (TCC) 212. When the TCC is locked, torque is transferred directly from the impeller 285 to the turbine 286. The TCC is electrically operated by a controller 12. Alternatively, the TCC can be hydraulically locked. In one example, the torque converter may be referred to as a component of the transmission.

[0027] When the torque converter lock-up clutch 212 is fully disengaged, the torque converter 206 transmits engine torque to the automatic transmission 208 via fluid transfer between the torque converter turbine 286 and the torque converter impeller 285, thereby doubling the torque. Conversely, when the torque converter lock-up clutch 212 is fully engaged, engine output torque is directly transferred to the input shaft (not shown) of the transmission 208 via the torque converter clutch. Alternatively, the torque converter lock-up clutch 212 may be partially engaged, thereby enabling adjustment of the amount of torque directly transmitted to the transmission. The controller 12 may be configured to adjust the amount of torque transmitted through the torque converter 206 by adjusting the torque converter lock-up clutch in response to various engine operating conditions or based on driver-based engine operation requests.

[0028] The automatic transmission 208 includes a gear clutch (e.g., gears 1-6) 211 and a forward clutch 210. The gear clutch 211 (e.g., 1-10) and the forward clutch 210 can be selectively engaged to propel the vehicle. Torque output from the automatic transmission 208 can then be transmitted to the wheels 216 to propel the vehicle via the output shaft 260. Specifically, the automatic transmission 208 can transfer input drive torque at the input shaft 270 in response to vehicle driving conditions before transmitting output drive torque to the wheels 216.

[0029] Furthermore, friction can be applied to the wheels 216 by engaging wheel brake 218. In one example, wheel brake 218 can be engaged in response to the driver pressing his foot on the brake pedal (not shown). In other examples, the controller 12 or a controller linked to the controller 12 can apply engagement of the wheel brake. In the same manner, friction to the wheels 216 can be reduced by disengaging wheel brake 218 in response to the driver releasing his foot from the brake pedal. Additionally, as part of an automatic engine stop procedure, friction can be applied to the wheels 216 via the controller 12 using the vehicle brakes.

[0030] Controller 12 can be configured to receive input from engine 10, such as Figure 1 As shown in more detail below, the controller 12 controls the torque output of the engine and / or the operation of the torque converter, transmission, DISG, clutch, and / or brakes accordingly. For example, torque output can be controlled by adjusting a combination of spark timing, fuel pulse width, fuel pulse timing, and / or air charge by controlling throttle opening and / or valve timing, valve lift, and boost pressure in turbocharged or supercharged engines. In the case of a diesel engine, the controller 12 can control engine torque output by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. In all cases, engine control can be performed on a cylinder-by-cylinder basis to control engine torque output. As known in the prior art, the controller 12 can also control torque output and electrical energy production from the DISG by adjusting the magnetic field flowing into and out of the DISG and / or the current in the armature winding. The controller 12 receives the DISG position via a position sensor 271, which also indicates the position of the shaft 241 and the mechanically driven transfer fluid pump 295. The controller 12 can convert the transmission input shaft position into input shaft speed by differentiating the signal from the position sensor 271. The controller 12 can receive the transmission output shaft torque from the torque sensor 272. Alternatively, the sensor 272 can be a position sensor or a torque and position sensor. If the sensor 272 is a position sensor, the controller 12 differentiates the position signal to determine the transmission output shaft speed. The controller 12 can also differentiate the transmission output shaft speed to determine the transmission output shaft acceleration.

[0031] When the idle-stop condition is met, controller 12 can initiate engine shutdown by cutting off fuel and spark to the engine. However, in some examples, the engine may continue to rotate. Furthermore, to maintain torque in the transmission, controller 12 can ground the rotating elements of transmission 208 to transmission housing 259 and thus to the vehicle frame. When the engine restart condition is met and / or when the vehicle operator wants to start the vehicle, controller 12 can reactivate engine 10 by turning starter engine 10 and resuming cylinder combustion.

[0032] Figure 1 and Figure 2 The system provides a system comprising: a vehicle including an engine; a motor selectively coupled to the engine; and a controller including executable instructions stored in a non-transitory memory for: reversing the engine via the motor without burning air and fuel in response to an exhaust sensor diagnostic request, and the controller including instructions for propelling the vehicle via the motor. The system also includes additional instructions for burning air and fuel in the engine and reversing the engine. The system also includes a particulate filter and an exhaust valve located in an exhaust system coupled to the engine, the exhaust valve being downstream of the particulate filter. The system also includes additional instructions for opening and closing the exhaust valve while reversing the engine. The system also includes a differential pressure sensor configured to sense pressure on two opposite sides of the particulate filter. The system also includes additional instructions for comparing the output of the differential pressure sensor when the exhaust valve is open with the output of the differential pressure sensor when the exhaust valve is closed. The system also includes additional instructions for adjusting engine operation in response to the comparison. The system includes a starter / generator integrated into the motor.

[0033] Now refer to Figure 3A This diagram illustrates exemplary valve timing for a first engine. The forward and reverse engine rotation directions are indicated by arrows. The exhaust valve opening timing is indicated by the outer ring 303. The intake valve opening timing is indicated by the inner ring 301. Valve timing is based on cylinder position top dead center (TDC) and bottom dead center (BDC). The exhaust valve closing time (EVC) for forward engine rotation is at 302. The exhaust valve opening time (EVO) for forward engine rotation is at 306. The intake valve closing time (IVC) for forward engine rotation is at 308. The intake valve opening time (IVO) for forward engine rotation is at 304. If the engine rotates in reverse, EVO occurs at 302 and EVC occurs at 306. IVO occurs at 308 and IVC occurs at 304.

[0034] Therefore, it can be observed that the intake valve opening duration is longer than the exhaust valve opening duration. Furthermore, IVO is close to TDC and IVC is close to BDC for forward-rotating engines. EVO is after BDC and EVC is after TDC for forward-rotating engines. Reverse-rotating engines allow air to be drawn in from the exhaust manifold and expelled from the intake manifold, such that air is drawn into the cylinder when the exhaust valve is open and expelled from the cylinder when the intake valve is open. Therefore, for the valve timing illustrated in this diagram, at the same engine speed, the airflow through the engine when the engine is rotating with the intake throttle open and in forward direction without fuel is greater than the airflow through the engine when the engine is rotating with the intake throttle open and in reverse direction without fuel. The increased airflow through the engine when it is rotating forward at the first engine speed is likely due to the longer intake valve opening duration and the intake valve opening and closing timing. The reduced airflow through the engine when it rotates in the reverse direction at the first speed may be due to the shorter exhaust valve opening duration and exhaust valve opening and closing timing compared to the intake valve opening duration and intake valve opening and closing time. However, utilizing Figure 3A The valve timing, which causes the engine to rotate in the opposite direction, is still useful when diagnosing exhaust sensors because the muffler's limitations when the engine is rotating in the opposite direction prepare for the pressure drop across the particulate filter.

[0035] Now refer to Figure 3B This diagram illustrates exemplary valve timing for rotating the engine in reverse (e.g., counter-clockwise) at a higher flow rate when diagnosing exhaust sensor readings. The forward and reverse engine rotation directions are indicated by arrows. Exhaust valve opening timing is indicated by outer ring 303. Intake valve opening timing is indicated by inner ring 301. Valve timing is referenced to cylinder positions: Top Dead Center (TDC) and Bottom Dead Center (BDC). The exhaust valve closing time (EVC) for forward engine rotation is at 310. The exhaust valve opening time (EVO) for forward engine rotation is at 314. The intake valve closing time (IVC) for forward engine rotation is at 316. The intake valve opening time (IVO) for forward engine rotation is at 312. If the engine rotates in reverse, EVO occurs at 310 and EVC occurs at 314. IVO occurs at 316 and IVC occurs at 312.

[0036] Therefore, it can be observed that the exhaust valve opening duration is longer than the intake valve opening duration. Furthermore, IVO is close to TDC and IVC is just before BDC for forward-rotating engines. EVO is close to BDC and EVC is close to TDC for forward-rotating engines. Reverse-rotating engines allow air to be drawn in from the exhaust manifold and expelled from the intake manifold, such that air is drawn into the cylinder when the exhaust valve is open and expelled from the cylinder when the intake valve is open. For these reasons, at the same engine speed, the airflow through the engine when the engine is rotating with the intake throttle open and without fuel in reverse is greater than the airflow through the engine when the engine is rotating with the intake throttle open and without fuel in forward rotation. The increased airflow through the engine when it is rotating in reverse at the first engine speed is likely due to the longer exhaust valve opening duration and exhaust valve opening and closing timing. The decreased airflow through the engine when it is rotating forward at the first engine speed is likely due to the shorter intake valve opening duration and intake valve opening and closing timing compared to the exhaust valve opening duration and exhaust valve opening and closing time. Therefore, whether the airflow through the engine when rotating it forward at a first engine speed is greater than the airflow through the engine when rotating it backward at the same first engine speed depends on the intake and exhaust valve timings, including the valve opening duration and valve opening and closing times. Thus, for some engine configurations, rotating the engine forward at a given engine speed provides more airflow through the engine compared to rotating the same engine backward at the same given engine speed. On the other hand, when the engine is rotated backward at a given engine speed, some engines provide more airflow through the engine compared to rotating the same engine forward at the same engine speed. In this way, the direction of engine rotation can be selected to increase the airflow through the engine, allowing the engine to rotate at a lower speed when diagnosing exhaust sensors. For example, if rotating a particular engine backward at a desired engine speed provides a greater airflow through the engine compared to rotating it forward at that desired engine speed, then rotating the engine backward can be used to diagnose exhaust sensors to improve the signal-to-noise ratio of the exhaust sensors.

[0037] Now refer to Figure 4 This shows the vehicle operation sequence. Figure 4 The vehicle operation sequence can be achieved through Figure 1 and Figure 2 The system provides this. Vehicle operation sequences can also be based on... Figures 5A-5C The method is provided.

[0038] from Figure 4The first graph, starting at the top, is a graph showing the relationship between the exhaust sensor (e.g., a gasoline particulate filter (GPF) sensor) diagnostic request status and time. The vertical axis represents the exhaust sensor diagnostic status, and an exhaust sensor diagnostic request is made when trace 402 is at a higher level near the arrow on the vertical axis. No exhaust sensor diagnostic request is made when trace 402 is at a lower level near the horizontal axis. The horizontal axis represents time, and time increases from the left to the right of the graph.

[0039] from Figure 4 The second curve starting from the top is the exhaust valve (e.g., Figure 1 73) A graph showing the relationship between operating state and time. When trace 404 is at a higher level near the vertical axis arrow, the exhaust valve is open. When trace 404 is at a lower level near the horizontal axis, the exhaust valve is closed. The horizontal axis represents time, and time increases from the left to the right of the graph.

[0040] from Figure 4 The third curve at the top is a graph showing the relationship between engine operating state and time. When trace 406 is horizontally "on" along the vertical axis, the engine can rotate forward and burn air and fuel. When trace 406 is horizontally "off" along the vertical axis, the engine stops and does not rotate. When trace 406 is horizontally "reverse" along the vertical axis, the engine rotates in the opposite direction without burning air and fuel. The horizontal axis represents time, and time increases from the left to the right of the curve.

[0041] from Figure 4 The fourth graph, starting from the top, is a graph showing the relationship between differential GPF pressure (e.g., ΔGPF pressure) and time. The vertical axis represents... Figure 1 The differential GPF pressure output (e.g., differential pressure) of the exhaust sensor 38 shown increases along the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left to the right of the graph. The differential GPF pressure is zero when trace 408 is close to the horizontal axis.

[0042] from Figure 4 The fifth graph, starting from the top, is a graph showing the relationship between the exhaust sensor degradation state and time. The vertical axis represents the exhaust sensor degradation state, and when trace 410 is at a higher level near the arrow on the vertical axis, it indicates exhaust sensor degradation. When trace 410 is at a lower level near the horizontal axis, it does not indicate exhaust sensor degradation. The horizontal axis represents time, and time increases from the left to the right of the graph.

[0043] At time T0, the engine is on and running (e.g., burning air and fuel), no exhaust sensor diagnostics are requested, and the exhaust valves are open. Furthermore, the differential pressure across the GPF is at a low level, and there is no indication of exhaust sensor degradation.

[0044] At time T1, the engine stops, and the differential pressure across the GPF begins to decrease. No exhaust sensor diagnostics are requested, and the exhaust valve remains open. No indication of exhaust sensor degradation is found.

[0045] At time T2, as indicated by trace 402 transitioning to a higher level, an exhaust sensor diagnostic is requested. This diagnostic can be requested after a threshold amount of time or distance has elapsed due to vehicle driving. Alternatively, if the engine has operated for a threshold amount of time without prior exhaust sensor diagnostics, an exhaust sensor diagnostic can be requested when the engine is stopped. For example, if the exhaust valve has not opened and closed within the threshold amount of time, an exhaust sensor diagnostic can be performed when the engine is not operating. The exhaust valve remains open, and the engine remains off. The differential pressure across the GPF is zero, and no exhaust sensor degradation is indicated.

[0046] Between time points T2 and T3, the vehicle's operating conditions remain unchanged and exhaust sensor diagnostics do not begin. Exhaust sensor diagnostics can be delayed after the engine stops so that vehicle passengers can leave the area without being disturbed by the diagnostics.

[0047] At time T3, exhaust sensor diagnostics begin and the engine rotates in reverse. The engine can be rotated via starter 96 or DISG 240. The engine is rotated without fuel supply. The exhaust valve is closed, and the exhaust sensor diagnostics remain asserted. If the downstream hose is connected to the exhaust system and exhaust sensor 38, resulting in a low differential pressure across the GPF, the exhaust valve can be closed to increase the resistance between atmospheric pressure and the downstream side of GPF 71. However, if the downstream hose is not connected to the exhaust system and exhaust sensor, a low-resistance path exists at the GPF inlet, making the pressure drop at the upstream side 38A of the exhaust pressure sensor more significant. Due to engine rotation, the differential pressure across the GPF begins to increase as the airflow through the engine increases. The exhaust sensor does not indicate degradation. Additionally, the engine intake throttle is open (not shown).

[0048] Between times T3 and T4, the differential pressure increases to a higher level and then stabilizes. After the differential pressure has stabilized, it is sampled near time T3 via controller 12, and the sampled value is stored in memory. The exhaust sensor diagnostic status remains active, and the exhaust valve remains closed. The engine continues to rotate in reverse, and there is no indication of exhaust sensor degradation.

[0049] At time T4, the exhaust valve is open and the engine continues to rotate in reverse. Opening the exhaust valve reduces the drag between atmospheric pressure and the downstream side of the GPF 71. If the downstream hose 38D is connected to the exhaust sensor 38 and the exhaust system 39, a larger differential pressure can be observed through the exhaust sensor 38. Similarly, if the downstream hose 38D is disconnected from the exhaust system 39 or the exhaust sensor 38, the differential pressure observed through the exhaust sensor 38 will be larger because atmospheric pressure is available on the downstream side of the GPF, which increases the pressure drop across the GPF. No indication of exhaust sensor degradation.

[0050] Between times T4 and T5, the differential pressure decreases only slightly and then stabilizes. After the differential pressure has stabilized, it is sampled near time T5 via controller 12, and the sampled value is stored in memory. The differential pressure sampled exactly before time T4 is compared with the differential pressure sampled exactly before time T5. The exhaust sensor diagnostic status remains active, and the exhaust valve remains closed. The engine continues to rotate in reverse, and no exhaust sensor degradation is indicated.

[0051] At time T5, controller 12 determines that the differential pressure change shortly before time T4 and shortly before time T5 is less than a threshold change. As a result, exhaust sensor degradation is determined to have occurred and is activated. However, if the differential pressure change exceeds the threshold amount, it will indicate a pressure change due to GPF flow, which can be anticipated when the flow through the engine and exhaust is high and a downstream hose connects between exhaust sensor 38 and exhaust system 39. Engine rotation stops and the differential pressure begins to decrease. The engine throttle also closes (not shown). Shortly after time T5, exhaust sensor diagnostics are canceled, but the exhaust sensor degradation state remains active.

[0052] Now refer to Figures 5A-5C The diagram illustrates a method for operating a vehicle. This method can be at least partially implemented by storing... Figure 1 and Figure 2 The executable instructions are stored in the controller memory of the system. Furthermore, the method may include actions taken in the material world for transformation. Figure 1 and Figure 2 The method provides the system's operational state actions. Additionally, this method can provide... Figure 4 The sequence of operations is shown below.

[0053] At point 502, method 500 determines the vehicle's operating condition. The vehicle's operating condition can be determined by receiving input from controller 12, such as... Figure 1 and Figure 2The inputs shown are used to determine the vehicle operating conditions. These may include, but are not limited to, vehicle speed, engine speed, engine torque, driver-demanded torque, drivetrain disengagement clutch operating status, vehicle mileage, transmission operating status, drivetrain disengagement clutch application pressure, DISG speed, DISG torque, and ambient temperature. After determining the vehicle operating conditions, method 500 proceeds to 504.

[0054] At 504, method 500 determines whether exhaust sensor diagnostics are desired. Exhaust sensor diagnostics can be desired at predetermined intervals (e.g., after the vehicle has been driven a predetermined distance or a predetermined amount of time). Additionally, in some examples, exhaust sensor diagnostics can be requested in response to the output of the exhaust sensor. If method 500 determines that exhaust sensor diagnostics are desired, the answer is yes and method 500 proceeds to 506. Otherwise, the answer is no and method 500 proceeds to 599.

[0055] At point 599, method 500 operates the engine to burn air and fuel while simultaneously rotating the engine clockwise. Method 500 also stores particulate matter from the engine in the GPF and responds to exhaust sensors (e.g., Figure 1 The output of sensor 38 in the middle is used to regenerate the GPF from time to time. Method 500 proceeds to exit.

[0056] At point 506, method 500 determines whether the vehicle includes an exhaust valve (e.g., Figure 1 (Exhaust valve 73 shown). Method 500 may include a variable stored in memory indicating whether the vehicle includes an exhaust valve. An exhaust valve may be included to provide a performance sound to the vehicle when the exhaust valve is open and a subdued sound to the vehicle when the exhaust valve is closed. If method 500 determines that the vehicle includes an exhaust valve, the answer is yes and method 500 proceeds to 540. Otherwise, the answer is no and method 500 proceeds to 508.

[0057] At 508, the method determines whether the vehicle is shut down. The vehicle can be determined to be shut down when the vehicle transponder moves away from the vehicle to a predetermined distance or when the ignition key is removed from the vehicle. When the vehicle is shut down, the engine stops and the vehicle does not move. If method 500 determines that the vehicle is shut down, then method 500 proceeds to 510. Otherwise, method 500 returns to 504. In some examples, method 500 may also require the vehicle to be shut down for a predetermined amount of time before proceeding to 510. Furthermore, method 500 may further require that the vehicle passengers have left the vehicle before method 500 proceeds to 510.

[0058] At 510, method 500 closes the engine intake throttle valve. The intake throttle valve can be closed while the engine is rotating to reduce the flow through it, so that even though the engine may be rotating, only a small pressure drop across the GPF can be observed via the exhaust sensor. Method 500 proceeds to 512.

[0059] At point 512, method 500 begins to reverse the rotation of the engine. Reversing the engine increases the amount of air pumped through it. Furthermore, it reduces the amount of energy required to rotate the engine. The engine can be started via a starter (e.g., Figure 1 96) or DISG (e.g., Figure 2 (240) Reverse rotation. When the engine is rotating in reverse, no fuel is supplied to the engine. Method 500 proceeds to 514.

[0060] At point 514, method 500 measures the exhaust gas sensor (e.g., Figure 1 The method 500 samples the output of the exhaust pressure sensor (38) and stores the measured output in the controller memory. Method 500 may wait a predetermined amount of time before measuring the exhaust sensor output to allow the operating conditions to stabilize. Because the engine intake throttle is closed, the differential pressure measured by the exhaust sensor should be low regardless of whether the exhaust sensor hose is connected to the exhaust system as intended. After sampling the exhaust pressure sensor output, method 500 proceeds to 516.

[0061] At position 516, method 500 opens the engine intake throttle valve. By opening the engine intake throttle valve, the airflow through the engine and GPF should increase, thus causing an increase in the differential pressure across the GPF if the exhaust sensor is correctly connected to the exhaust system. If the downstream hose (e.g., Figure 1 The differential pressure sensor (38D) is disconnected because the downstream side of the differential pressure sensor is exposed to atmospheric pressure and the increase in differential pressure will be less because the upstream side of the differential pressure sensor is likely to be almost closer to atmospheric pressure. Method 500 proceeds to 518.

[0062] At point 518, method 500 measures the exhaust gas sensor (e.g., Figure 1 The output of (38) is measured and stored in the controller memory. Method 500 may wait a predetermined amount of time before measuring the output of the exhaust sensor to allow the operating conditions to stabilize. Because the engine intake throttle is open, the differential pressure measured by the exhaust sensor should be high unless the downstream hose of the exhaust sensor is disconnected from the exhaust system. If the downstream hose is disconnected from the exhaust system, the differential pressure observed by the exhaust pressure sensor should be lower than the differential pressure when the downstream hose is connected to the exhaust system under the same conditions. Method 500 proceeds to 520.

[0063] At 520, method 500 stops the engine from rotating and closes the engine intake throttle valve. By stopping the engine from rotating, a smaller current can be drawn from the vehicle battery. Method 500 proceeds to 522.

[0064] At point 522, method 500 determines whether the pressure difference obtained by subtracting the pressure difference output by the exhaust sensor when the engine throttle is closed from the pressure difference output by the exhaust sensor after the engine throttle is open is greater than a threshold pressure difference. If yes, the answer is yes and method 500 proceeds to point 530. If no, the answer is no and method 500 proceeds to point 524.

[0065] At 530, method 500 indicates no exhaust sensor degradation. Method 500 may prevent exhaust sensor degradation from taking effect when the differential pressure is determined to be at the desired level during diagnostics. Method 500 proceeds to 532.

[0066] At point 532, method 500 adjusts the engine operating threshold to obtain the maximum engine power and speed. Method 500 then exits.

[0067] At 524, method 500 indicates exhaust sensor degradation. Method 500 indicates exhaust sensor degradation by illuminating a light, changing the value of a variable in the controller's memory, or by providing a visual indication via a human / machine interface. Method 500 proceeds to 526.

[0068] At point 526, method 500 adjusts the engine operating threshold to make reduced engine power and speed available. For example, method 500 can reduce the engine power limit so that the engine can output 70% of its maximum engine power when exhaust sensor degradation is present. In other examples, engine power may be unrestricted, but particulate filter regeneration can be provided more frequently. For example, instead of regenerating the vehicle's particulate filter every 1000 km, the particulate filter temperature may be increased every 500 km. By increasing the particulate filter regeneration frequency, the likelihood of large amounts of carbonaceous material accumulating in the particulate filter can be reduced. Method 500 proceeds to exit.

[0069] At position 540, method 500 determines the exhaust valve (e.g., Figure 1 73) In this case, is the exhaust valve in an open or closed state? In one example, a variable in the controller memory indicates the state of the exhaust valve. If method 500 determines that the exhaust valve is closed, the answer is yes and method 500 proceeds to 542. Otherwise, the answer is no and method 500 proceeds to 546.

[0070] At 542, method 500 determines the differential pressure indicated by the exhaust pressure sensor. In one example, method 500 may determine the differential pressure by sampling the exhaust valve output after the engine has been operating at a predetermined engine speed and load for a predetermined amount of time. For example, method 500 may sample the differential pressure sensor output after the engine has been operating at 1600 RPM and 100 N-m of torque for at least 3 seconds. Method 500 proceeds to 544.

[0071] At 544, method 500 determines whether the time elapsed since the last time the exhaust valve opened and the exhaust sensor sampled the differential pressure. For example, if the time elapsed for the threshold amount is twenty minutes, and two hours have passed since the exhaust valve opened and the exhaust sensor differential pressure output was sampled when the engine is operating at the predetermined engine speed and load described at 542, then the answer is yes and method 500 proceeds to 570. However, if the exhaust valve opened and the exhaust sensor was sampled less than twenty minutes after the engine was operating at the predetermined engine speed and load described at 542, before the exhaust sensor was sampled at the same time the engine was operating at the predetermined engine speed and load mentioned at 542, then the answer is no and method 500 proceeds to 550. If the time elapsed since the last time the exhaust valve opened and the exhaust sensor was sampled at the predetermined speed and load described at 546 is greater than the threshold amount, then the answer is yes and method 500 proceeds to 570. Otherwise, the answer is no and method 500 proceeds to 550.

[0072] Therefore, step 544 may require the exhaust valve to open and close for a time period of a threshold value to verify the operation of the exhaust sensor. This check is useful when the exhaust valve is manually controlled. Furthermore, when requesting exhaust sensor diagnostics, it is desirable to prevent automatic adjustment of the exhaust valve position so that vehicle occupants are not disturbed by intrusive monitoring.

[0073] At 546, method 500 determines the differential pressure indicated by the exhaust pressure sensor. In one example, method 500 may determine the differential pressure by sampling the exhaust valve output after the engine has been operating at a predetermined engine speed and load for a predetermined amount of time. For example, method 500 may sample the differential pressure sensor output after the engine has been operating at 1600 RPM and 100 N-m of torque for at least 3 seconds. Method 500 proceeds to 548.

[0074] At 548, method 500 determines whether the time elapsed since the last time the exhaust valve closed and the exhaust sensor sampled the differential pressure. For example, if the time elapsed for the threshold amount is twenty minutes, and two hours have passed since the exhaust valve closed and the exhaust sensor differential pressure output was sampled when the engine is operating at the predetermined engine speed and load described at 542, then the answer is yes and method 500 proceeds to 570. However, if the exhaust valve closed and the exhaust sensor was sampled less than twenty minutes after the engine was operating at the predetermined engine speed and load described at 542, before the exhaust sensor was sampled at the same time the engine was operating at the predetermined engine speed and load mentioned at 542, then the answer is no and method 500 proceeds to 550. If a time elapsed longer than the threshold amount since the last time the exhaust valve closed and the exhaust sensor was sampled at the predetermined speed and load described at 546, then the answer is yes and method 500 proceeds to 570. Otherwise, the answer is no and method 500 proceeds to 550.

[0075] Therefore, step 548 may require the exhaust valve to open and close to verify the operation of the exhaust sensor within a threshold time. This check is useful when the exhaust valve is manually controlled.

[0076] At 550, method 500 determines the difference between the output of the exhaust sensor when the exhaust valve is open and the engine is operating at a predetermined speed and load, and the output of the exhaust sensor when the exhaust valve is closed and the engine is operating at a predetermined speed and load. Method 500 proceeds to 552.

[0077] At point 552, method 500 determines whether the pressure difference obtained by subtracting the pressure difference output by the exhaust sensor when the exhaust valve is open from the pressure difference output by the exhaust sensor when the exhaust valve is closed is greater than the threshold pressure difference. If yes, the answer is yes and method 500 proceeds to point 554. If not, the answer is no and method 500 proceeds to point 558.

[0078] At 554, method 500 indicates no exhaust sensor degradation. Method 500 may prevent exhaust sensor degradation from taking effect when the differential pressure is determined to be at the desired level during diagnostics. Method 500 proceeds to 556.

[0079] At point 556, method 500 adjusts the engine operating threshold to make the maximum engine power and speed available. Method 500 then exits.

[0080] At 558, method 500 indicates exhaust sensor degradation. Method 500 can indicate exhaust sensor degradation by illuminating a light, changing the value of a variable in the controller's memory, or by providing a visual indication via a human / machine interface. Method 500 proceeds to 560.

[0081] At point 560, method 500 adjusts the engine operating threshold to achieve reduced engine power and speed. For example, method 500 may reduce the engine power limit so that the engine can output 70% of its maximum power when exhaust sensor degradation is present. In other examples, engine power may be unrestricted, but particulate filter regeneration may be provided more frequently. For example, instead of regenerating the vehicle's particulate filter every 1000 km, the particulate filter temperature may be increased every 500 km. By increasing the particulate filter regeneration frequency, the likelihood of large amounts of carbonaceous material accumulating in the particulate filter can be reduced. Method 500 proceeds to exit.

[0082] At point 570, method 500 determines whether the vehicle is off. The vehicle is considered off when its engine stops, the vehicle stops, and the key or other device is outside a predetermined range from the vehicle. Additionally, the vehicle is considered off when there are no longer any passengers in the vehicle. Furthermore, in some examples, method 500 may require a predetermined amount of time to have elapsed since the vehicle was off before method 500 proceeds to point 572. If method 500 determines that the vehicle is off, then method 500 proceeds to point 572. Otherwise, method 500 exits.

[0083] In this way, method 500 can attempt to diagnose exhaust sensor operation while the vehicle is running, but exhaust sensor diagnosis can be delayed until the vehicle is turned off if the exhaust valves do not open and close in a timely manner when the engine is operating at the desired engine speed and load.

[0084] At 572, method 500 opens the engine intake throttle valve and closes the exhaust valve. The intake throttle valve can open when the engine is running and the exhaust valve is closed because the muffler reduces the flow through the engine and the GPF, resulting in a small pressure drop across the GPF. Method 500 proceeds to 574.

[0085] At point 574, method 500 begins to reverse the rotation of the engine. Reversing the engine increases the amount of air pumped through it. Furthermore, it reduces the amount of energy required to rotate the engine. The engine can be started via a starter (e.g., Figure 1 96) or DISG (e.g., Figure 2 (240) Reverse rotation. When the engine is rotating in reverse, no fuel is supplied to the engine. Method 500 proceeds to 576.

[0086] At position 576, method 500 measures the exhaust gas sensor (e.g., Figure 1The method 500 samples the output of the exhaust pressure sensor (38) and stores the measured output in the controller memory. Method 500 may wait a predetermined amount of time before measuring the exhaust sensor output to allow the operating conditions to stabilize. Because the engine intake throttle is closed, the differential pressure measured by the exhaust sensor should be low regardless of whether the exhaust sensor hose is connected to the exhaust system as expected. After sampling the exhaust pressure sensor output, method 500 proceeds to 578.

[0087] At point 578, method 500 opens the exhaust valve. By opening the exhaust valve, the airflow through the engine and GPF should increase due to the lack of resistance via the muffler, thus causing an increase in the differential pressure across the GPF if the exhaust sensor is correctly connected to the exhaust system. If the downstream hose (e.g., Figure 1 The differential pressure sensor (38D) is disconnected because the downstream side of the differential pressure sensor is exposed to atmospheric pressure and because the upstream side of the differential pressure sensor is likely much closer to atmospheric pressure, the increase in differential pressure can be minimal. Method 500 proceeds to 580.

[0088] At 580, method 500 measures the exhaust gas sensor (e.g., Figure 1 The output of 38) is measured and stored in the controller memory. Method 500 may wait a predetermined amount of time before measuring the output of the exhaust sensor to allow the operating conditions to stabilize. Because the engine intake throttle is open, the differential pressure measured by the exhaust sensor should be high unless the downstream hose of the exhaust sensor is disconnected from the exhaust system. If the downstream hose is disconnected from the exhaust system, the differential pressure observed by the exhaust pressure sensor should be lower than the differential pressure when the downstream hose is connected to the exhaust system under the same conditions. Method 500 proceeds to 582.

[0089] At 582, method 500 stops the engine from rotating and closes the engine intake throttle valve. Method 500 also returns the exhaust valve to its state when the vehicle was initially turned off. By stopping the engine from rotating, less current can be drawn from the vehicle battery. Method 500 proceeds to 584.

[0090] At point 584, method 500 determines whether the pressure difference obtained by subtracting the pressure difference output by the exhaust sensor when the exhaust valve is closed from the pressure difference output by the exhaust sensor after the exhaust valve is open is greater than a threshold pressure difference. If yes, the answer is yes and method 500 proceeds to point 586. If not, the answer is no and method 500 proceeds to point 590.

[0091] At 586, method 500 indicates no exhaust sensor degradation. Method 500 may prevent exhaust sensor degradation from taking effect when the differential pressure is determined to be at the desired level during diagnostics. Method 500 proceeds to 588.

[0092] At point 588, method 500 adjusts the engine operating threshold to make the maximum engine power and speed available. Method 500 then exits.

[0093] At 590, method 500 indicates exhaust sensor degradation. Method 500 indicates exhaust sensor degradation by illuminating a light, changing the value of a variable in the controller's memory, or by providing a visual indication via a human / machine interface. Method 500 proceeds to 592.

[0094] At point 592, method 500 adjusts the engine operating threshold to make a reduction in engine power and speed available. For example, method 500 can reduce the engine power limit so that the engine can output 70% of its maximum engine power when exhaust sensor degradation is present. In other examples, engine power may be unrestricted, but particulate filter regeneration can be provided more frequently. For example, instead of regenerating the vehicle's particulate filter every 1000 km, the particulate filter temperature may be increased every 500 km. By increasing the particulate filter regeneration frequency, the likelihood of large amounts of carbonaceous material accumulating in the particulate filter can be reduced. Method 500 then concludes.

[0095] Therefore, method 500 provides a vehicle operation method comprising: in response to an exhaust system sensor diagnostic request, reversing the engine without fuel being added; receiving data from a differential pressure sensor to a controller while reversing the engine; and adjusting engine operation via the controller in response to the data from the differential pressure sensor. The method includes wherein adjusting engine operation includes regenerating a particulate filter. The method includes wherein adjusting engine operation includes limiting engine power output. The method further includes closing the engine intake throttle valve while reversing the engine. The method further includes opening the engine intake throttle valve while reversing the engine. The method further includes opening the engine intake throttle valve and closing the exhaust valve while reversing the engine. The method further includes opening the engine intake throttle valve and opening the exhaust valve while reversing the engine. The method includes wherein adjusting engine operation via the controller in response to data from the differential pressure sensor includes adjusting engine operation when the data from the differential pressure sensor indicates that the pressure change between a first state when the exhaust valve is open and a second state when the exhaust valve is closed is less than a threshold value. The method includes adjusting engine operation via a controller in response to data from a differential pressure sensor, including not adjusting engine operation when data from the differential pressure sensor indicates that the pressure change between a first state when the exhaust valve is open and a second state when the exhaust valve is closed is greater than a threshold.

[0096] Method 500 also provides a vehicle operation method comprising: in response to an exhaust system sensor diagnostic request, measuring a pressure drop across a particulate filter located downstream of the engine while the exhaust valve is open and when the exhaust valve is closed, simultaneously with the combustion of air and fuel in the engine; and in response to the sensor diagnostic request and in response to the exhaust valve not changing its state for a threshold amount of time while the engine is burning air and fuel, measuring the pressure drop across the particulate filter while the engine is not burning air and fuel and is rotating in the reverse direction. The method further includes comparing the pressure drop across the particulate filter when the exhaust valve is closed with the pressure drop across the particulate filter when the exhaust valve is open. The method also includes adjusting engine operation in response to the comparison of the pressure drop across the particulate filter when the exhaust valve is closed with the pressure drop across the particulate filter when the exhaust valve is open.

[0097] Note that the example control and estimation programs included herein can be used with various engine and / or vehicle system configurations. Furthermore, the methods described herein can be a combination of actions taken by a controller in the physical world and instructions within the controller. At least a portion of the control methods and programs disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system including a controller combined with various sensors, actuators, and other engine hardware. The specific programs described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Therefore, the various actions, operations, and / or functions described can be executed in the order shown, executed in parallel, or omitted in some cases. Similarly, the processing order is not required to realize the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. Depending on the specific strategy used, one or more of the shown actions, operations, and / or functions can be repeatedly executed. Additionally, the described actions, operations, and / or functions can be graphically represented as code encoded into a non-transitory memory of a computer-readable storage medium in an engine control system, wherein the described actions are realized by cooperating with an electronic controller to execute instructions in a system including various engine hardware components.

[0098] This concludes the specification. Various alterations and modifications will arise in those skilled in the art upon reading this specification without departing from its spirit or scope. For example, I3, I4, I5, V6, V8, V10, and V12 engines operating with natural gas, gasoline, diesel, or alternative fuels may benefit from this specification.

Claims

1. A vehicle operation method comprising: in response to an exhaust system sensor diagnostic request, reverse rotating an engine without fueling the engine; receiving data from a differential pressure sensor to a controller while the engine is being reverse rotated, the differential pressure sensor configured to sense pressure on two opposing sides of a particulate filter; and in response to the data from the differential pressure sensor, adjusting engine operation via the controller.

2. The method of claim 1, wherein adjusting engine operation comprises regenerating a particulate filter.

3. The method of claim 1, wherein adjusting engine operation comprises limiting engine power output.

4. The method of claim 1, further comprising: closing an engine intake throttle while the engine is being reverse rotated.

5. The method of claim 1, further comprising: opening an engine intake throttle while the engine is being reverse rotated.

6. The method of claim 1, further comprising: opening an engine intake throttle and closing an exhaust valve downstream of the particulate filter while the engine is being reverse rotated.

7. The method of claim 1, further comprising: opening an engine intake throttle and opening an exhaust valve downstream of the particulate filter while the engine is being reverse rotated.

8. The method of claim 1, wherein adjusting engine operation via the controller in response to the data from the differential pressure sensor comprises: adjusting engine operation when the data from the differential pressure sensor indicates a pressure change between a first condition when an exhaust valve downstream of the particulate filter is open and a second condition when the exhaust valve is closed is less than a threshold.

9. The method of claim 8, wherein adjusting engine operation via the controller in response to the data from the differential pressure sensor comprises: not adjusting engine operation when the data from the differential pressure sensor indicates the pressure change between the first condition when the exhaust valve is open and the second condition when the exhaust valve is closed is greater than a threshold.

10. A system for a vehicle comprising: a vehicle comprising an engine; a motor selectively coupled to the engine; and a controller comprising executable instructions stored in non-transitory memory for: in response to an exhaust sensor diagnostic request, reverse rotating the engine via the motor without combusting air and fuel, receiving data from a differential pressure sensor to the controller while the engine is being reverse rotated, the differential pressure sensor configured to sense pressure on two opposing sides of a particulate filter; and in response to the data from the differential pressure sensor, adjusting engine operation.

11. The system of claim 10, further comprising additional instructions for: combusting air and fuel in the engine and forward rotating the engine.

12. The system of claim 10, further comprising a particulate filter and an exhaust valve in an exhaust system coupled to the engine, the exhaust valve downstream of the particulate filter.

13. The system of claim 12, further comprising additional instructions for: opening and closing the exhaust valve while the engine is being reverse rotated.

14. The system of claim 12, further comprising additional instructions for: comparing an output of the differential pressure sensor when the exhaust valve is open to an output of the differential pressure sensor when the exhaust valve is closed.

15. The system of claim 10, wherein the controller comprises instructions for propelling the vehicle via the motor.

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