Gasoline particulate filter diagnosis

Abstract

The present disclosure relates to gasoline particulate filter diagnostics, providing methods and systems for diagnosing a gasoline particulate filter in an exhaust system. In one example, a method can include, during a condition in which a differential pressure sensor is exposed to varying exhaust pressure, indicating degradation of a hose coupled across a particulate filter in an exhaust system in response to a differential pressure change measured by the differential pressure sensor differing from an expected change, the differential pressure sensor positioned in the hose, and the particulate filter positioned upstream of an exhaust tuning valve.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to exhaust treatment systems for combustion engines, and in particular to diagnostics for particulate matter filters for gasoline engines. BACKGROUND

[0002] Internal combustion engines, particularly gasoline engines with direct injection, generate fine particulate matter during engine operation that can be subject to emissions standards. To achieve emissions compliance, a gasoline particulate filter (GPF) can be included in the engine exhaust to trap particulate matter before the exhaust is released to the atmosphere, where the regeneration of the filter and filter operation can be controlled and periodically evaluated. At times, the particulate filter can fail to trap particulate matter due to degradation of the filter. In other cases, the filter can be missing or removed from the exhaust system. To detect a degraded or missing GPF, one or more pressure sensors can be used for diagnostics, and such sensors can be coupled upstream and / or downstream of the GPF.

[0003] Accordingly, various types of pressure sensors have been developed that are configured to detect filter degradation and monitor filter performance. One example method shown in Nieuwstadt, U.S. Patent No. 6,947,831, discloses using a differential pressure sensor to determine the status of a particulate filter for regeneration purposes. By monitoring the differential pressure across the filter and comparing the differential pressure to a threshold value, filter regeneration can be performed, or degradation of the filter can be diagnosed. Nieuwstadt also discloses that the differential pressure sensor can degrade, resulting in a false determination that the filter itself has become degraded. Therein, a comparison of the expected pressure response to actual pressure readings based on exhaust flow changes can be used to indicate pressure sensor degradation, and filter regeneration is controlled accordingly.

[0004] However, the present inventors have recognized potential problems with the above-described methods. As one example, a connection of a differential pressure sensor in an exhaust system downstream and / or upstream of a particulate filter can become disconnected, resulting in inaccurate pressure readings. Additionally, in a vehicle system that includes an exhaust tuning valve in addition to a differential pressure sensor, a missing or degraded particulate filter can be undetectable if the downstream hose connection between the particulate filter and the differential pressure sensor becomes disconnected and the exhaust tuning valve is closed. In the case of the exhaust tuning valve being closed and the downstream hose being disconnected or degraded, the increase in exhaust back pressure caused by the closing of the valve is sensed by the differential pressure sensor on the upstream hose side of the differential pressure sensor, while the downstream hose side of the differential pressure sensor senses atmospheric pressure. Thus, the differential pressure sensor can measure an increase in differential pressure when the exhaust tuning valve is closed and the downstream hose is disconnected, which can mimic the pressure drop measured by the differential pressure sensor when there is an intact, non-degraded GPF, even when the GPF is missing or degraded. SUMMARY

[0005] In one example, the above-described problems can be solved by a method comprising, during a condition in which a differential pressure sensor is exposed to varying exhaust gas pressure, indicating degradation of a hose coupled across a particulate filter in an exhaust system upstream of an exhaust tuning valve in response to a differential pressure change measured by the differential pressure sensor being different than an expected change.

[0006] As such, GPF diagnosis can be performed with higher reliability, and a distinction can be made between degradation of the particulate filter and disconnection of the differential pressure sensor, which can have become disconnected during engine operation. Overall, the accuracy and reliability of diagnosing the exhaust particulate filter is improved, while achieving higher emissions compliance.

[0007] It is to be understood that the foregoing summary of the application is provided in simplified form to introduce selected concepts of the application, which will be further described in the detailed description. This is not meant to be determined the key or important features of the claimed subject matter, the scope of which is defined by the appended claims. Moreover, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages mentioned in the background or any part of this disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A schematic view of an internal combustion engine having an exhaust system with exhaust aftertreatment devices is shown.

[0009] Figure 2 A detailed view of Figure 1 exhaust aftertreatment devices is shown.

[0010] Figure 3 A flowchart showing a method for diagnosing degradation of a particulate filter is shown.

[0011] Figure 4 A flowchart showing a first embodiment of a method for diagnosing degradation of a downstream hose housing a differential pressure sensor is shown.

[0012] Figure 5 A graph depicting an output of a differential pressure sensor coupled across a particulate filter in an exhaust device is shown.

[0013] Figure 6 A graph depicting a detection threshold for a differential pressure output of a differential pressure sensor is shown.

[0014] Figure 7 An example illustration of operating parameters based on changes in differential pressure output during exhaust tuning valve open and closed durations to diagnose during a downstream hose disconnection is shown.

[0015] Figure 8 A flowchart is shown that illustrates a second embodiment of a method for diagnosing degradation of a downstream hose that houses a differential pressure sensor.

[0016] Figure 9 A flowchart is shown that illustrates a third embodiment of a method for diagnosing degradation of a downstream hose that houses a differential pressure sensor.

[0017] Figure 10 A flowchart is shown that illustrates a fourth embodiment of a method for diagnosing degradation of a downstream hose that houses a differential pressure sensor.

[0018] Figure 11 A graph is shown that depicts the output of a differential pressure sensor coupled across a particulate filter in an exhaust device, with an orifice located in an upstream hose.

[0019] Figure 12 A graph is shown that depicts the output of a differential pressure sensor coupled across a particulate filter in an exhaust device, with a pneumatic valve located in an upstream hose.

[0020] Figure 13 A graph is shown that depicts the output of a differential pressure sensor coupled across a particulate filter in an exhaust device, with a vented vacuum valve located in a downstream hose. DETAILED DESCRIPTION

[0021] The following specification details a method for operating an engine, such as Figure 1 the illustrated engine, equipped with a particulate filter, such as a gasoline particulate filter (GPF), coupled to a differential pressure (DP) sensor in an exhaust system with upstream and downstream connections. The exhaust system further includes an exhaust tuning valve, e.g., a wastegate, located downstream of both the filter and the differential pressure sensor, as Figure 2 illustrated. The exhaust tuning valve is controlled by the method to adjust backpressure from the exhaust, as Figure 4 illustrated. Further, degradation of the GPF can be monitored based on output from the DP sensor, as Figure 3 illustrated.

[0022] During engine operation, the differential pressure sensor to filter downstream connection can become disconnected, and detection of GPF degradation can become challenging if the exhaust tuning valve is in a closed position, as illustrated by the graph of Figures 5 to 6 Therefore, during selected conditions, the engine controller can be configured to perform an invasive test operation to assess degradation of the downstream hose connection by estimating the output of the differential pressure sensor. In particular, the controller can perform a diagnostic routine, such as Figure 4The example routine shown, where the exhaust tuning valve can first be held open, and a corresponding first differential pressure can be obtained from the output of the differential pressure sensor, then the exhaust tuning valve can be held closed, and a second differential pressure can be obtained from the output of the differential pressure sensor, as shown in the illustration of Figure 7 FIG. 1. The differential pressure calculated by the controller can then be evaluated against a diagnostic threshold indicative of deterioration of the downstream connection of the DP sensor to the GPF of the engine exhaust system. If it is found that the downstream hose connection of the DP sensor is disconnected, the filter diagnostic routine can not be performed. In this way, filter performance can be reliably monitored and diagnosed, while improving vehicle diagnostics.

[0023] In another example, in an exhaust system having a passive exhaust tuning valve, the differential pressure sensor to filter downstream connection can become disconnected. The passive exhaust tuning valve can be a normally closed valve, and can be moved to an open position based on exhaust flow pressure flowing through the exhaust system (e.g., when exhaust flow or pressure is greater than a threshold, where the threshold can include exhaust flow generated during high engine load and / or high engine speed conditions). As described above, detection of GPF deterioration can be challenging with the exhaust tuning valve in the closed position. Because the passive exhaust tuning valve is not an actively controlled valve, invasive test operations for diagnosing downstream hose disconnection, as shown in Figure 4 FIG. 2, are not feasible. Accordingly, during selected conditions, the engine controller can be configured to perform one or more methods employing an orifice included in the upstream hose, a pneumatic valve located in the upstream hose, and / or a vent vacuum valve fluidly coupled to the downstream hose for diagnosing deterioration of the downstream hose having a passive exhaust tuning valve. In particular, during conditions where a change in mass air flow through the exhaust device occurs with the passive exhaust tuning valve closed, pressure measurements on the downstream side of the hose can be decoupled from pressure measurements on the upstream side (e.g., by closing the pneumatic valve or adjusting the position of the vent vacuum valve), and if the downstream side does not show a corresponding pressure change, deterioration can be indicated. In other examples, the pressure measured on the upstream side can change more slowly than the pressure measured on the downstream side (e.g., by including an orifice), and if a differential pressure decrease is observed during a decrease in exhaust mass flow, deterioration can be indicated.

[0024] In particular, the controller can perform a diagnostic routine, such as Figures 8 to 10In the example routine shown, a corresponding first differential pressure can be obtained from the output of the differential pressure sensor under a first set of conditions, and then a second differential pressure obtained under a different set of conditions (e.g. by a change in air flow through the exhaust, by the accelerator pedal being depressed, by the accelerator pedal being released, etc.). The differential pressure change calculated by the controller can then be evaluated against a diagnostic threshold indicative of deterioration of the downstream connection of the DP sensor to the GPF of the engine exhaust system. If it is found that the downstream hose connection of the DP sensor is disconnected, then the filter diagnostic routine can not be performed.

[0025] In an example, the exhaust system includes an orifice in the upstream hose connection and a passive exhaust tuning valve. Deterioration of the downstream hose can be diagnosed when there is a change in air flow through the exhaust. The purpose of the orifice can be to reduce pressure fluctuations or exhaust flow changes, thus resulting in a smooth signal output from the DP sensor, and for example further to cause the upstream hose to depressurize at a slower rate than the downstream hose during a released accelerator pedal event. A first pressure output from the DP sensor can be obtained under steady state conditions (e.g. where there is no substantial change in exhaust mass flow). In an event where a mass air flow change is detected, an additional pressure output can be obtained from the DP sensor. Further, a differential pressure sensor output change can be calculated as a function of time. If such a change is determined to be less than a threshold, it can indicate the downstream hose as disconnected. This is because when the downstream hose is disconnected, the downstream side of the differential pressure continues to measure atmospheric pressure, even as the upstream side measures exhaust pressure changes, resulting in a relatively large change (e.g. decrease) in differential pressure. By contrast, when the downstream hose is connected, both the upstream and downstream pressures will change, although the upstream pressure will change at a slower rate than the downstream pressure. This can result in a brief increase in differential pressure, followed by a decrease in differential pressure as the downstream hose depressurizes faster than the upstream hose during a decrease in exhaust flow.

[0026] In an example, the exhaust system includes a pneumatic valve in an upstream hose connection with a passive exhaust tuning valve. Degradation of the downstream hose can be diagnosed when there is a change in air flow through the exhaust. Here, a first pressure output from the DP sensor can be calculated when the pneumatic valve is actuated to open. In an event that detects a change in mass air flow, the pneumatic valve can be fully closed and one or more additional pressure outputs from the DP sensor can be obtained. The change in differential pressure sensor output can then be calculated and compared to a diagnostic threshold to determine whether the downstream hose is disconnected. If the hose is disconnected, the closing of the valve will cause an unchanging differential pressure due to both the upstream and downstream sides of the differential pressure sensor being exposed to a constant pressure (due to trapping of exhaust upstream of the closed valve and the downstream side being exposed to atmosphere via the disconnected hose). By contrast, when the downstream hose is connected, the closing of the valve causes a changing differential pressure due to the upstream side measuring a constant pressure and the downstream side measuring a pressure that changes with mass flow of exhaust.

[0027] In an example, the exhaust system includes a vent vacuum valve in a downstream hose connection with a passive exhaust tuning valve. Degradation of the downstream hose can be diagnosed during invasive actuation of the vent vacuum valve. Here, a first pressure output from the DP sensor can be obtained prior to actuation of the vent vacuum valve. The vent vacuum valve can then be actuated / adjusted such that exhaust flow into the downstream hose can be impeded while the downstream end of the DP sensor can be exposed to atmosphere. A second pressure output from the DP sensor can be measured and then the change in differential pressure sensor output can be calculated and compared to a diagnostic threshold to determine whether the downstream hose is disconnected. When the downstream hose is disconnected, adjusting the vent vacuum valve to expose the downstream side of the differential pressure sensor to atmosphere will not cause a change in the output of the differential pressure sensor because the downstream side of the differential pressure sensor will be exposed to atmosphere due to the hose disconnection prior to adjusting the vent vacuum valve. By contrast, when the hose is connected, adjusting the vent vacuum valve will cause a change (e.g., increase) in the differential pressure.

[0028] Reference is now made to Figure 1 which includes a schematic view showing one cylinder of a multi-cylinder internal combustion engine 10. The engine 10 can be controlled at least in part by a control system including a controller 12 and inputs from a vehicle operator 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP.

[0029] The combustion cylinder 30 of the engine 10 can include a combustion cylinder wall 32 having a piston 36 located therein. The piston 36 can be coupled to a crankshaft 40 such that the reciprocating motion of the piston is translated into rotational motion of the crankshaft. The crankshaft 40 can be coupled to at least one drive wheel of the vehicle via an intervening transmission system. Further, a starter motor can be coupled to the crankshaft 40 via a flywheel to enable starting operation of the engine 10.

[0030] The combustion cylinder 30 can receive intake air from an intake manifold 44 via an intake port 42 and can exhaust combustion gases via an exhaust port 48. The intake manifold 44 and the exhaust port 48 can selectively communicate with the combustion cylinder 30 via respective intake valves 52 and exhaust valves 54. In some embodiments, the combustion cylinder 30 can include two or more intake valves and / or two or more exhaust valves.

[0031] In this example, the intake valves 52 and the exhaust valves 54 can be controlled by cam actuation via respective cam actuation systems 51 and 53. The cam actuation systems 51 and 53 can each include one or more cams and can utilize one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems that can be operated by the controller 12 to vary the valve operation. The positions of the intake valves 52 and the exhaust valves 54 can be determined by position sensors 55 and 57, respectively. In alternative embodiments, the intake valves 52 and / or the exhaust valves 54 can be controlled by electric motor-actuated valvetrains. For example, the cylinder 30 can alternatively include intake valves controlled via electric motor-actuated valvetrains and exhaust valves controlled via cam actuation including CPS and / or VCT systems.

[0032] The illustrated fuel injector 66 is directly coupled to the combustion cylinder 30 for directly injecting fuel to the cylinder 30 in proportion to the pulse width of a signal FPW received from the controller 12 via an electronic driver 68. In this manner, the fuel injector 66 provides direct injection of so-called fuel to the combustion cylinder 30. For example, the fuel injector can be mounted on a side of the combustion cylinder or in a head of the combustion cylinder. Fuel can be delivered to the fuel injector 66 by a fuel delivery system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some embodiments, the combustion cylinder 30 can alternatively or additionally include a fuel injector arranged in the intake port 42 by a configuration that provides port injection of so-called fuel to an intake port upstream of the combustion cylinder 30.

[0033] Intake passage 42 may include a charge motion control valve (CMCV) 74 and CMCV plate 72, and may also include throttle 62 having throttle plate 64. In this particular example, the position of throttle plate 64 may be varied by controller 12 via a signal provided to an electric motor or actuator included with throttle 62. This configuration may be referred to as electronic throttle control (ETC). In this manner, throttle 62 may be operated to vary intake air provided to combustion cylinder 30, as well as to other engine combustion cylinders. Intake passage 42 may include a mass air flow sensor 120 and a manifold air pressure sensor 122 for providing respective signals MAF and MAP to the controller.

[0034] Ignition system 88 can provide an ignition spark to combustion chamber 30 via spark plug 92 in response to spark advance signal SA from controller 12, under select operating modes. Though spark ignition components are shown, in some embodiments, combustion chamber 30 or one or more other combustion chambers of engine 10 may be operated in a compression ignition mode, with or without an ignition spark.

[0035] Exhaust gas sensor 126 is shown coupled to exhaust passage 48 upstream of exhaust aftertreatment device 70. Sensor 126 may be any suitable sensor for providing an indication of exhaust gas air / fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide pre-exhaust oxygen sensor), a two-state oxygen sensor or EGO, HEGO (heated EGO), NO x , HC or CO sensor. The exhaust aftertreatment device 70 may include a gasoline particulate filter (GPF) and one or more emission control devices, such as a three-way catalyst (TWC) coupled together or separately (see below). Figure 2 In other embodiments, one or more emission control devices may be a NOx trap, various other emission control devices, or combinations thereof.

[0036] The controller 12 Figure 1The controller 12 is shown as a microcomputer including a microprocessor unit 102, input / output ports 104, electronic storage media for executable programs and calibration values shown in this particular example as a read-only memory chip 106, random access memory 108, non-volatile memory 110, and a data bus. The controller 12 can receive various signals from sensors coupled to the engine 10 including, in addition to those signals discussed previously, a measurement of intake mass air flow (MAF) from a mass air flow sensor 120, engine coolant temperature (ECT) from a temperature sensor 112 coupled to the cooling jacket 114, a surface ignition pick-up signal (PIP) from a Hall effect sensor 118 (or other type) coupled to the crankshaft 40, throttle position (TP) from a throttle position sensor, and absolute manifold pressure signal MAP from a pressure sensor 122. The storage media read-only memory 106 can be programmed with computer readable data representing instructions executable by the processor 102 for performing the methods described below and variations thereof. The controller 12 receives signals from various sensors of the engine 10 and employs various actuators of the engine 10 to adjust engine operation based on the received signals and instructions stored on the controller's memory. Figure 1 Figure 1

[0037] Figure 2 A detailed view of the exhaust system 200 of the engine coupled to Figure 1 is shown schematically. Figures 1 to 2 ​​Example configurations are shown with relative positioning of various components. At least in one example, if the illustrated elements are in direct contact or direct coupling with one another, such elements can be referred to as being in direct contact or direct coupling, respectively. Similarly, at least in one example, elements shown as being adjacent or next to one another can be so referred to, respectively. As an example, components placed in coplanar contact with one another can be referred to as being coplanarly in contact. As another example, at least in one example, elements positioned apart from one another with only space therebetween and no other components can be so referred to. As yet another example, elements shown as being above / below one another, on opposite sides of one another, or to the left / right of one another can be so referred to relative to one another. Further, as shown in the figures, at least in one example, the highest element or the highest point of an element can be referred to as the "top" of the component, and the lowest element or the lowest point of an element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the figures and used to describe the positioning of the elements of the figures relative to one another. Thus, in one example, an element shown above other elements is positioned vertically above the other elements. As yet another example, the shape of an element depicted within the figures can be referred to as having those shapes (e.g., such as circular, straight, planar, curved, rounded, beveled, angled, etc.). Further, at least in one example, elements shown intersecting one another can be referred to as intersecting elements or intersecting one another. Still further, in one example, an element shown within another element or shown outside another element can be so referred to.

[0038] The exhaust system 200 includes an exhaust passage 48 and an exhaust aftertreatment device 70. The exhaust aftertreatment device 70 includes a three-way catalyst 204 and a gasoline particulate filter 206 mounted in a common housing. According to one embodiment of the present disclosure, the TWC 204 can be positioned upstream of the GPF 206 and can serve to reduce emissions by allowing catalytic oxidation of CO and hydrocarbons while performing catalytic reduction of NOx. The catalytic material can include precious metals such as platinum, palladium, and / or rhodium. Exhaust gas that has been treated by passing through the TWC can then be filtered for particulate matter before being emitted into the atmosphere. As used herein, "upstream" and "downstream" can be relative to the direction of exhaust flow. For example, the TWC 204 located upstream of the GPF 206 includes a TWC that receives exhaust gas from the engine and flows the exhaust gas toward the GPF.

[0039] GPF 206 can be composed of a heat-resistant porous filter wall made of ceramic, metal fiber cloth, or other materials and structures that inhibit the path of particulate matter but do not completely close off the exhaust gas and allow it to pass through a porous path. Still further, the structure can be arranged in tiers or layers. Exhaust gas discharged from the exhaust port of cylinder 30 can flow into exhaust passage 48 and past GPF, and in the process, particulate matter can be deposited / filtrated by the GPF. GPF 206 can be used to retain residual soot discharged from engine 10 to reduce emissions. In some examples, the retained particulate matter can be further oxidized to produce CO2 in a forced regeneration process performed during engine operation.

[0040] While the depicted embodiment shows TWC device 204 positioned upstream of GPF 206, in alternative embodiments, a TWC or its substitute can be positioned downstream of the particulate matter filter. In still further embodiments, the filter substrate can include a catalytic coating comprising one or more layers of a three-way catalyst.

[0041] In addition to cylinder 30, exhaust passage 48 can receive exhaust gas from other cylinders of engine 10. A plurality of sensors can be coupled to the exhaust system including exhaust aftertreatment device 70. Exhaust gas temperature can be estimated by one or more temperature sensors, such as temperature sensor 216 located downstream of exhaust aftertreatment device 70. Alternatively or additionally, exhaust gas temperature can be inferred based on engine operating conditions such as speed, load, air-fuel ratio (AFR), ignition retard, and the like. A catalytic monitoring sensor (CMS) 214 can be connected in exhaust aftertreatment device 70 downstream of TWC 204 and downstream of a pre-catalytic oxygen sensor, such as UEGO sensor 126, to monitor conversion efficiency of TWC 204. Catalytic converter performance can be monitored with a suitable number of exhaust gas sensors including lambda sensors or proportional oxygen sensors.

[0042] A differential pressure (DP) sensor 208 is coupled to exhaust aftertreatment device 70 across GPF 206. According to embodiments of the present disclosure, DP sensor 208 is connected to an upstream side of the GPF via an upstream hose 210 and to a downstream side of the GPF via a downstream hose 212. Upstream hose 210 includes a first end connected to the DP sensor and a second end connected to upstream of GPF 206 (and downstream of TWC 204) in the exhaust aftertreatment device. Downstream hose 212 includes a first end connected to the DP sensor and a second end connected to downstream of GPF 206 in the exhaust aftertreatment device.

[0043] In a first embodiment, upstream hose 210 may include a small orifice 226 positioned in the upstream exhaust gas flow path. This orifice 226 acts as a mechanical low-pass filter, reducing pressure or exhaust gas flow variations and thereby smoothing the signal from the DP sensor. The presence of the orifice in the upstream hose can stabilize upstream pressure fluctuations typically seen under high exhaust gas flow conditions, thereby allowing the signal from the DP sensor to stabilize. In a second embodiment, upstream hose 210 may include a pneumatic valve 228 fluidically coupled to the upstream hose. In one example, the pneumatic valve may be an active valve controlled by pneumatic pressure provided by a pneumatic actuator controlled by a controller. When open, pneumatic valve 228 allows DP sensor 208 to measure exhaust gas pressure upstream of the GPF. When closed, pneumatic valve 228 blocks fluid coupling between the region upstream of the GPF and the DP sensor, thereby preventing the DP sensor from measuring pressure upstream of the GPF. In a third embodiment, downstream hose 212 may include a fluidically coupled vent vacuum valve 230. The vent vacuum valve 230 can be coupled to the downstream hose so that when the vent vacuum valve is in a first position, the exhaust gas flowing into the downstream hose can be transferred to the DP sensor via the vent vacuum valve 230 to measure the exhaust pressure downstream. The position of the vent vacuum valve 230 can be changed by the controller 12, wherein the controller can adjust the position of the valve to block the exhaust gas flow into the downstream hose. When adjusted to the second position, the vent vacuum valve can block the fluid coupling of the downstream exhaust gas to the DP sensor, and can further allow the downstream end of the DP sensor to sense atmospheric conditions, thereby simulating a downstream hose disconnected state. As an example, one or more of the hose components mentioned above can exist alone, or can exist in combination. For example, both the orifice and the vent vacuum valve can be present in the exhaust system. In other examples, all hose components can be present in the exhaust system. In examples where more than one hose component is present in the exhaust system, if one of the components is utilized (for example, as described below with respect to Figure 9 If a diagnostic routine for a pneumatic valve (described in more detail below) indicates degradation, the system may be repaired by another diagnostic routine (e.g., using a pneumatic valve as described below). Figure 10 A vent vacuum valve (described in more detail) confirms degradation of the downstream hose.

[0044] Although Figure 2 Upstream hose 210 and downstream hose 212 are shown as each coupled to exhaust aftertreatment device 70, but in some examples, one or more of upstream hose 210 and downstream hose 212 may be coupled to exhaust passage 48. For example, downstream hose 212 may be fluidly coupled to exhaust passage 48 downstream of GPF 206 rather than being fluidly coupled to a housing of aftertreatment device 70.

[0045] Accordingly, the differential pressure sensor 208 observes the upstream and downstream pressures across the GPF 206, and the output of the DP sensor 208 is a differential pressure. An increase in the differential pressure between the upstream and downstream sides of the GPF 206 is related to an increase in the relative amount of particulate matter accumulated in the particulate filter as exhaust continues to flow through. Accordingly, the controller 12 can be configured to estimate the amount of particulate matter accumulated in the GPF 206 based on the output of the DP sensor. In some embodiments, an absolute pressure sensor (not shown) can be coupled to the particulate filter at some location in the exhaust tract to provide an estimate of the back pressure generated in the particulate filter and an estimate of the filter load. In still other embodiments, a pressure sensor can be coupled to the upstream and downstream of the filter, and the filter load can be based on the estimated differential pressure across the filter. In some examples, the differential pressure measured by the DP sensor can also be affected by various components that can be coupled in the upstream and downstream hose connections of the particulate filter, such as the orifice described above.

[0046] A muffler 220 is also positioned downstream of the exhaust device 70. The muffler 220 can reduce the magnitude of the sound pressure generated by the exhaust gas before the exhaust gas enters the atmosphere. The exhaust gas 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 travel via the exhaust tract 48 and / or tailpipe of the exhaust system en route to the atmosphere.

[0047] The exhaust system 200 includes an exhaust tuning valve 218 that is controlled to regulate a portion of the exhaust gas that flows through the muffler 220. The exhaust tuning valve 218 is installed in the exhaust system 200 downstream of the exhaust device 70 and downstream of the DP sensor 208, with the exhaust tuning valve 218 coupled to the muffler 220 in a parallel passage 224. Depending on whether the exhaust tuning valve 218 is in an open or closed position, under certain conditions, exhaust gas that is expelled via the exhaust system of the internal combustion engine 10 can pass through the exhaust tuning valve 218. In one embodiment, when the exhaust tuning valve 218 is in a closed position, exhaust gas can exit (e.g., to the atmosphere) only by passing through the exhaust tract 48 and the muffler 220 of the exhaust system 200. When the exhaust tuning valve 218 is in an open position, at least a portion of the exhaust gas can bypass the muffler 220 and pass through the parallel passage 224 of the exhaust tuning valve 218 to the atmosphere. In some embodiments, the exhaust tuning valve 218 can be a butterfly valve, a flapper valve, or another type of valve that can be controlled to regulate the flow of exhaust gas through the exhaust system 200. Figure 2The passage 224 is shown. In one example, the open and closed positions of the exhaust tuning valve 218 can be varied by the controller 12. The controller 12 can receive signals and communications from various sensors coupled to the engine 10, such as from sensors coupled to the exhaust 70, and accordingly, can actuate the exhaust tuning valve position to adjust the amount of exhaust passing through the muffler. In other examples, the exhaust tuning valve 218 can be a passively controlled valve that remains closed until the exhaust pressure exceeds a threshold, at which point the exhaust tuning valve can open. In some examples, the exhaust tuning valve can be operated to be partially open or partially closed, allowing exhaust to pass partially through the muffler and partially through the exhaust tuning valve and into the passage 224 before exiting into the atmosphere.

[0048] During engine operation, exhaust flows from the exhaust tract 48 into the exhaust aftertreatment device 70. In the exhaust aftertreatment device 70, according to one embodiment of the disclosure, the exhaust first passes through the TWC 204 for removal of CO, hydrocarbons, and NOx. A catalytic sensor, such as the CMS 214, can be positioned downstream of the TWC 204 in the exhaust aftertreatment device 70 to monitor the exhaust and / or efficiency of the TWC 204, and can send signals to the controller 12. The exhaust can then progress toward the GPF 206, where the exhaust is filtered to remove particulate matter contaminants. Over time, particulate matter can accumulate on the walls of the filter, which can increase back pressure, causing a negative impact on fuel economy. Accordingly, this accumulation of particulate matter is burned off (e.g., regenerated) at regular intervals. Due to the temperature of the exhaust and the close coupled location of the GPF relative to the engine, regeneration of the GPF can occur relatively regularly without having to perform a specific regeneration routine. However, under certain conditions or due to certain driving cycles (e.g., city driving), particulate matter can accumulate on the GPF, and accordingly, there can be a need to regenerate the GPF. For example, filter regeneration can be initiated at fixed intervals of vehicle mileage or when the exhaust back pressure reaches a threshold, which can be determined based on the output of the differential pressure sensor reaching a selected output. Herein, the differential pressure sensor monitors the loading of particulate matter on the GPF, and the controller can initiate regeneration in response to the loading reaching a threshold level. To regenerate the GPF, the engine can be operated at a rich air-fuel ratio, a reductant can be injected into the exhaust, and / or other adjustments can be made to burn off the accumulated particulate matter.

[0049] The differential pressure sensor can also be used to detect degradation of the GPF, where the pressure drop across the GPF is affected by the volume of exhaust flowing and the loading of particulate matter present on the GPF, among other factors. Accordingly, a decrease in the differential pressure across the GPF identified by the DP sensor 208 can indicate GPF degradation.

[0050] According to the embodiments of the present disclosure, it is possible to use Figure 2 A differential pressure sensor 208 is shown to diagnose degradation of the gasoline particulate filter 206, where the DP sensor 208 outputs the difference in exhaust pressure upstream and downstream of the GPF 106. Figure 2 As shown, differential pressure sensor 108 is connected to the upstream side of GPF 206 via upstream hose 210 and to the downstream side of GPF 206 via downstream hose 212. Thus, differential pressure sensor 208 observes both the upstream and downstream pressures across GPF 206, whereas the output of DP sensor 208 is a differential pressure (e.g., delta pressure). In the event that the hose upstream of the DP sensor is disconnected / decoupled from the exhaust passage, the output of the DP sensor drops below a certain threshold, indicating a disconnected hose, and thus the controller identifies a defect in the exhaust system (e.g., a fault). Figure 5 However, in the event that the downstream hose of the DP sensor is disconnected from the exhaust passage, the controller may not be able to detect the downstream hose disconnection (e.g., Figure 5 ), because the upstream side of the differential pressure sensor measures the exhaust pressure upstream of the GPF, while the downstream side measures atmospheric pressure, and therefore the output of the differential pressure sensor can simulate the pressure drop across the GPF.

[0051] Figure 5 Graph 500 depicts the output of a differential pressure sensor coupled across a particulate filter in an exhaust system, such as, for example, DP sensor 208 coupled across GPF 206. The vertical axis represents the differential pressure output from DP sensor 208 across the particulate filter, and increases in differential pressure are shown in the direction of the vertical axis arrow. The horizontal axis represents the differential pressure output across the particulate filter. Figure 2 The exhaust volume flow of the exhaust system shown. The graph includes a threshold line 508, below which the upstream hose disconnection state can be indicated. Curve 506 shows the differential pressure as a function of the exhaust volume flow under the condition that the upstream hose (e.g., such as upstream hose 210) including the DP sensor is disconnected from the GPF. When the upstream hose is disconnected, the open end of the upstream hose can sense the atmospheric conditions. In this case, the downstream hose is still connected to the GPF at the downstream end, and the downstream exhaust pressure can be measured. Therefore, the differential pressure calculated by the DP sensor can show the differential pressure, such as Figure 5 The differential pressure measured when the upstream hose is disconnected (curve 506) may be lower than the detection threshold 508, and thus the upstream hose disconnect condition may be easily identified.

[0052] Under certain conditions, the downstream hose of the DP sensor 208 can become disconnected from the GPF (e.g., downstream hose 212), and the downstream hose open end can sense atmospheric conditions. As shown by curve 502, under such conditions, the output of the DP sensor will be the difference between the upstream exhaust pressure and the atmospheric pressure (from the open end). As the exhaust flow volume increases through the exhaust system 200 during engine operation, the differential pressure measured with the downstream hose disconnected also increases accordingly. Curve 504 shows the differential pressure as a function of exhaust volume flow in the exhaust system including the DP sensor as a complete downstream hose. Curve 502 can be indistinguishable from curve 504 at least at lower exhaust mass flow rates, such that it can not be possible to distinguish between a disconnected downstream hose and a complete downstream hose based on the differential pressure output of the DP sensor. When the downstream hose is connected, the exhaust pressure upstream of the particulate filter exceeds the downstream exhaust pressure (e.g., such as shown by curve 504), and in the example where the downstream hose becomes disconnected, the upstream exhaust pressure still exceeds the downstream pressure (e.g., such as shown by curve 502). Thus in both examples, the differential pressure output is above a detection threshold 508. Thus, Figure 5 The downstream hose disconnected condition can not be easily identified under all conditions.

[0053] As explained previously, some engine systems can include an exhaust tuning valve in the exhaust passage, such as Figure 2 exhaust tuning valve 218. The exhaust tuning valve 218 is installed in the exhaust system 200 downstream of both the exhaust device 70 and the DP sensor 208 in the exhaust passage 224 parallel to the muffler 220. Depending on whether the exhaust tuning valve 218 is in an open or closed state, exhaust can pass through the exhaust tuning valve 218. In one example, the open and closed positions of the exhaust tuning valve 218 can be changed by the controller 12 depending on engine operating conditions to allow for a desired noise level.

[0054] In the event of the downstream hose of the DP sensor becoming disconnected / decoupled from the exhaust passage including the exhaust tuning valve 218, the DP sensor can not be able to detect a downstream hose disconnection as shown by Figure 6 when the exhaust tuning valve 218 is in a closed position (e.g., partially closed or fully closed).

[0055] Figure 6The illustrated graph 600 depicts differential pressure as a function of exhaust flow volume under different exhaust system conditions. Line 602 illustrates differential pressure measured in an exhaust system including a clean GPF (e.g., a new and intact GPF). Line 604 illustrates differential pressure measured in an exhaust system missing a GPF with the exhaust tuning valve fully closed and the downstream hose disconnected. Line 608 illustrates differential pressure measured in an exhaust system missing a GPF with the exhaust tuning valve fully open and the downstream hose disconnected. Line 610 illustrates differential pressure measured in an exhaust system missing a GPF (but with the downstream hose intact). Line 606 indicates a threshold differential pressure across the GPF below which a missing GPF can be identified (e.g., as illustrated by line 610) because the same pressure is measured by the upstream hose connection and the downstream hose connection of the DP sensor (e.g., free flowing exhaust due to a missing filter). In contrast, line 602 illustrates a clean and functioning GPF where the higher differential pressure is observed because the upstream exhaust pressure can be higher than the downstream exhaust pressure measured by the downstream hose connection of the DP sensor due to the upstream hose connection.

[0056] Line 604 illustrates that, in an exhaust system missing a GPF, the missing GPF can be undetectable if the downstream hose connection of the DP sensor becomes disconnected and the exhaust tuning valve is in the fully closed position. When the exhaust tuning valve is fully closed, the back pressure introduced into the exhaust system can be measured as the upstream pressure by the upstream hose connection, while the disconnected downstream hose measures atmospheric conditions. Further, the differential pressure measured under such conditions (e.g., line 604 illustrates a missing GPF with the downstream hose disconnected and the exhaust tuning valve fully closed) can be indistinguishable from a clean GPF functioning in the exhaust system (e.g., line 602) and can lie above the detection threshold 606.

[0057] However, line 608 illustrates that a missing GPF with the downstream hose disconnected can be detected if the exhaust tuning valve is fully open. When the exhaust tuning valve is fully open, the upstream hose connection measures free flowing exhaust due to the missing GPF, and the downstream disconnected hose connection observes atmospheric conditions. Line 608 illustrates that the differential pressure measured by the DP sensor under such conditions is below the threshold 606 and, therefore, a missing GPF with the downstream hose disconnected can be detected when the exhaust tuning valve is fully open. Accordingly, in accordance with the disclosure herein and the following discussion regarding Figure 3 、 Figure 4 、 Figure 8 、 Figure 9 and Figure 10Embodiments described in greater detail below can test for deterioration of a downstream hose connection across a GPF by performing an intrusive test that includes adjusting an exhaust tuning valve position and / or by performing a passive test. In an exhaust system with a GPF and a DP sensor, if the downstream hose of the DP sensor becomes disconnected or deteriorated and the exhaust tuning valve downstream is in a closed position, a differential pressure above a threshold can be measured because the upstream end of the DP sensor measures the upstream exhaust pressure and back pressure from the closed exhaust tuning valve, while the disconnected hose downstream can measure atmospheric conditions (see Figure 6 ). If the exhaust tuning valve is adjusted to an open position, a differential pressure below a threshold can be measured because the upstream end of the DP sensor measures the upstream exhaust pressure and the disconnected hose downstream can measure atmospheric conditions, while back pressure is mitigated by opening the exhaust tuning valve (see Figure 6 ). Thus, by adjusting the exhaust tuning valve position from closed to open and measuring the differential pressure at both positions, the differential pressure change can indicate a downstream hose disconnected state. In one example, the exhaust tuning valve position can be adjusted from closed to open to measure the differential pressure, and in a second example, the exhaust tuning valve position can be adjusted from open to closed and the differential pressure measured.

[0058] However, a downstream hose disconnection can require a distinction from a deteriorated particulate filter. Figure 3 A method for diagnosing a particulate filter is shown, where the decision of whether to perform a diagnostic routine is based on whether a downstream hose is deteriorated. Figure 4 An example flowchart is shown that illustrates how a downstream hose disconnection can be detected by an intrusive test that adjusts an exhaust tuning valve from closed to open and how a downstream hose disconnection can be distinguished from a particulate filter deteriorated state. Figures 8 to 10 An example flowchart is shown that illustrates a method for detecting deterioration of a downstream hose in an exhaust system in the presence of a passive exhaust tuning valve.

[0059] Turning now to Figure 3 , a method 300 for diagnosing deterioration of a particulate filter, such as GPF 206, in accordance with the present disclosure is shown. Instructions for performing method 300 and the remaining methods included herein can be executed by controller 12 based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to Figures 1 to 2 , for example, DP sensor 208. The controller can employ an engine actuator of the engine system, for example an actuator coupled to and configured to adjust a position of exhaust tuning valve 218, to adjust engine operation in accordance with the methods described below.

[0060] At 302, the method includes estimating and / or measuring engine operating conditions. For example, these can include engine speed, torque demand, boost level, engine temperature, exhaust temperature, barometric pressure, fuel octane content, fuel composition (e.g., fuel alcohol content), particulate filter load, etc. Estimating engine operating conditions can additionally include determining a noise operating mode, which can be set according to an operator's preference. For example, an operator can enter a user input (e.g., via a touch display or other input mechanism communicatively coupled to the controller), select a desired noise mode, such as quiet, track, normal, etc.

[0061] At 304, the method includes adjusting the exhaust tuning valve, such as the exhaust tuning valve 218, during engine operation in accordance with the set noise mode. In one example, the controller can perform a calculation based on a lookup table (e.g., specific to the selected noise mode) that uses inputs for engine operating conditions (e.g., engine speed, load) and outputs for relative opening or closing of the exhaust tuning valve to adjust the opening and closing of the exhaust tuning valve 218. For example, at low speed and engine idle conditions, the exhaust tuning valve can be closed, while at high speed engine conditions, the exhaust valve can be tuned to an open position.

[0062] As another example, the exhaust tuning valve can be an electronic exhaust tuning valve, and can be set directly by an operator according to the operator's preference. Additionally, a preset strategy can be employed, such as can automatically tune (e.g., open and close) the electronic exhaust tuning valve based on the operator's preferences and driving habits.

[0063] For example, in other examples, the exhaust tuning valve can be a passive valve that automatically (e.g., without a command from the controller) opens when exhaust pressure exceeds a threshold.

[0064] At 306, the method 300 determines whether particulate filter diagnostic conditions are met. The particulate filter diagnostic conditions can include that the particulate matter load of the filter is within a desired range, that the temperature of the particulate filter is below a threshold, that steady state engine operation (e.g., in which the exhaust mass flow and intake throttle position each change by less than a threshold amount), that a predetermined amount of time has elapsed since a previous diagnostic routine was completed, etc. If the particulate filter diagnostic conditions are not met, then the method 300 moves to 308 and waits to perform the filter diagnostic routine until the diagnostic determining conditions have been met. However, if the diagnostic conditions are met, then the method 300 proceeds to 310 to determine whether a downstream hose connected to the particulate filter has deteriorated / disconnected from the exhaust tract. In one example, the method of Figure 4 diagnosing downstream hose deterioration / disconnection according to Figure 4Methods of the present disclosure, downstream hose deterioration or disconnection can be identified by monitoring differential pressure across the GPF during conditions when the exhaust tuning valve is open and during conditions when the exhaust tuning valve is closed. By adjusting the exhaust tuning valve from closed to open, the differential pressure measurement using the output of a differential pressure sensor, such as DP sensor 208, can indicate that the downstream hose of the GPF is disconnected from the exhaust passage. In other examples, downstream hose deterioration / disconnection can be diagnosed according to the methods described in detail below with respect to Figures 8 to 10 Methods of the present disclosure, Figure 8 , Figure 9 and / or Figure 10 diagnose downstream hose deterioration / disconnection. For example, in vehicle systems employing a passive exhaust tuning valve, differential pressure across the GPF can be monitored during changing exhaust flow conditions (e.g., a soft accelerator pedal) to check the downstream hose connection of the GPF in the exhaust passage.

[0065] If the method 400 of Figure 4 the method 800 of Figure 8 the method 900 of Figure 9 and / or the method 1000 of Figure 10 indicates a downstream hose disconnection, the method 300 moves to 312 and the PF diagnostic routine is not performed despite the particulate filter condition being met. Further, in response to an indication of a downstream hose disconnection, one or more engine parameters can be adjusted to reduce engine out particulate matter load, such as spark timing, fuel injection amount, and torque limit. As previously described, the PF diagnostic routine relies on the output of a DP sensor coupled across the GPF in the exhaust passage. The reliability of the DP sensor output further depends on the upstream and downstream hose connections in communication with the exhaust passage. If the method 400 of Figure 4 the method 800 of Figure 8 the method 900 of Figure 9 and / or the method 1000 of Figure 10 indicates a downstream hose disconnection, unreliable diagnosis of PF function can result and, therefore, diagnosis of the PF can be delayed until the downstream hose connection is restored.

[0066] Returning to 310, when the answer at 310 is no (e.g., when a downstream hose disconnection is not indicated), the method 300 proceeds to 314 to measure differential pressure across the GPF. The differential pressure measured across the GPF is the output of a differential pressure sensor and is relied upon for determination of PF deterioration and, in some examples, only used if Figure 4 , Figure 8 , Figure 9 and / or Figure 10downstream of the exhaust passage. At 316, the method 300 determines whether the differential pressure measured across the GPF is different than an expected pressure. The expected differential pressure can be a range of differential pressures expected to be observed if the GPF is present and operating as expected. For example, the expected differential pressure can include a range of pressures from a lower limit pressure to an upper limit pressure, below which the GPF can be missing, and above which the GPF can be clogged, blocked, or otherwise have an accumulation of particulate matter greater than expected and thus indicative of a possible degradation of the GPF. If the differential pressure output by the DP sensor is found to be equal to the expected pressure across the GPF (e.g., within the range of expected pressures), then the method 300 moves to 318 and the result is a determination that the PF is not degraded. The method 300 then returns.

[0067] On the other hand, if the differential pressure is not equal to the expected pressure in the exhaust passage (e.g., if the differential pressure is outside the range of expected pressures), then the particulate filter can be degraded after the downstream hose connection has been verified. Accordingly, the method 300 proceeds to 320 to provide an indication of GPF degradation. The indication of GPF degradation can include outputting a notification of GPF degradation to an operator, such as by activating an indicator light and / or setting a diagnostic code. Further, in response to the indication of GPF degradation, one or more engine operating parameters can be adjusted to reduce the engine out particulate matter load, such as spark timing, engine output, boost pressure, and the like. The method 300 then returns.

[0068] Figure 4 is a flowchart illustrating a method 400 for diagnosing a downstream hose connection, where the downstream hose (such as the downstream hose 208) is connected to the exhaust passage downstream of the GPF. At 402, the method 400 determines whether the differential pressure measured across the GPF is different than an expected pressure. The expected differential pressure can be a range of differential pressures expected to be observed if the GPF is present and operating as expected. For example, the expected differential pressure can include a range of pressures from a lower limit pressure to an upper limit pressure, below which the GPF can be missing, and above which the GPF can be clogged, blocked, or otherwise have an accumulation of particulate matter greater than expected and thus indicative of a possible degradation of the GPF. If the differential pressure output by the DP sensor is found to be equal to the expected pressure across the GPF (e.g., within the range of expected pressures), then the method 400 moves to 404 and the result is a determination that the PF is not degraded. The method 400 then returns. Figure 2downstream of the particulate filter, such as the GPF 206. At 402, the method includes estimating and / or measuring engine operating conditions. For example, the engine operating conditions can include engine speed, torque demand, boost level, engine temperature, exhaust temperature, air pressure, fuel octane content, fuel composition (e.g., fuel alcohol content), particulate filter load, etc. At 404, the method determines whether one or more entry conditions of a diagnostic test have been met, the diagnostic test verifying the connection of the downstream hose to the GPF in the exhaust apparatus. The entry conditions of the diagnostic test can be a set of predefined engine operating conditions that must all be met for the method 400 to proceed further, and can include the air mass being within a desired test range, a steady state condition as defined by a mass air flow variation being less than a threshold, no exhaust valve faults, no exhaust pressure sensor faults, the exhaust being warm enough for testing (as inferred by catalyst temperature measured by a temperature sensor such as sensor 216), the test not having been performed during the current trip (e.g., once per trip), the engine coolant temperature being above a threshold, a waiting period between diagnostic attempts being met (e.g., no rapid repetition of exhaust valve diagnostics), the vehicle speed being greater than a minimum speed threshold, the vehicle speed not being within a pass-by noise test range, the pedal position not being at the throttle full open position, and the vehicle not being in a deceleration fuel cut phase. In one example, the storage medium read only memory 106 can be programmed with instructions executable by the processor 102 to verify whether the entry conditions required for the diagnostic test are met. If all of the entry conditions are not met, the method 400 moves to 406 to continue to maintain the current engine operating conditions. In other examples, not all of the entry conditions must be met to proceed, e.g., a subset of the entry conditions can be met. Maintaining the current operating conditions can include continuing to adjust the exhaust valve, such as valve 218, based on the selected noise pattern. Maintaining the current operating conditions can further include monitoring the particulate filter load based on the output from the differential pressure sensor. The method 400 then returns.

[0069] However, if a subset or all of the entry conditions are satisfied at 404, the method 400 proceeds to begin an invasive diagnostic test for checking the downstream hose connection of the DP sensor coupled across the GPF. At 408, the method 400 begins an exhaust tuning valve open phase, which includes fully opening the exhaust tuning valve at 410. Once the exhaust valve is fully open, at 412, the method includes calculating a moving average of the output of the differential pressure sensor. In one example, the moving average differential pressure output can include a series of averages of different subsets of data accumulated over time by the controller. In another example, the moving average can be a cumulative moving average of all stored data outputs of the DP sensor, which can account for each new output data of the DP sensor and can further calculate an average of all data up to the current time. In yet another example, the average calculated can be a non-moving average, which can involve discrete data obtained at the time of the invasive test. As described herein, the open position of the exhaust tuning valve can operate to cause the exhaust bypass system to allow exhaust to flow to atmosphere via both the muffler and the exhaust tuning valve. Thus, the open position of the exhaust tuning valve can also serve to relieve any built-up back pressure in the exhaust system 200. The exhaust tuning valve can remain open for only a prescribed duration to allow for a determined average pressure output, and once the open test duration expires, the method 400 proceeds to close the valve at 414, ending the open phase of the exhaust tuning valve. In other examples, once the open phase expires, the exhaust tuning valve can be returned to control based on the selected noise pattern (e.g., the valve can be returned to a partially open position).

[0070] At 418, the method 400 begins an exhaust tuning valve close phase, which includes fully closing the exhaust tuning valve at 420. In some examples, the open phase of the routine can transition directly to the close phase (e.g., the close phase can begin as soon as the open phase ends). In other examples, the close phase can be spaced a duration of time from the open phase. In still further examples, the close phase can begin prior to the open phase.

[0071] After the exhaust valve is fully closed, the method includes calculating a moving average of the output of the differential pressure sensor at 422. As previously described, the closed position of the exhaust tuning valve can seal the exhaust bypass system and exhaust can only exit via the muffler 220 to enter the atmosphere. Due to the restricted flow of exhaust, the closed position of the exhaust tuning valve can further build up back pressure in the exhaust system 200. This back pressure can be measured by the DP sensor and can be accounted for when calculating the differential pressure output by a moving average with the exhaust valve in the closed position. The exhaust tuning valve can only remain closed for a prescribed duration to allow for a determined average pressure output, and once the test duration expires, the method 400 proceeds to open the valve at 424 to end the closed phase of the exhaust tuning valve.

[0072] At 426, the method 400 calculates the difference between the open moving average and the closed moving average of the DP sensor output obtained at 412 and 422. In one example, the difference can be an absolute value, such that the difference between the two average differential pressures is evaluated and the directionality of the difference can be disregarded. At 428, the method 400 determines whether the calculated differential pressure (e.g., the difference between the moving average of the DP sensor during the open and closed phases of the exhaust tuning valve at a given time) is greater than a threshold value. The threshold value referenced at 428 can be indicative of the output of the DP sensor being dependent on engine operating conditions, and can further represent a pressure value above which indicates that a deterioration of the downstream hose connection has occurred. If the calculated differential pressure is not found to be greater than the threshold value at 428, then the method 400 deems the downstream hose to be intact and connected to the exhaust device / exhaust tract downstream of the GPF 206 at 430. The method 400 then returns.

[0073] However, if the calculated differential pressure is found to be greater than the threshold value at 428, then the method 400 moves to 432 and diagnoses the downstream hose of the DP sensor as being disconnected from the exhaust system. As explained above with respect to Figure 3 the downstream hose being disconnected can obscure accurate particulate filter diagnosis. Accordingly, at least in some examples, in response to an indication that the downstream hose is disconnected, engine operating parameters can be adjusted to reduce engine out particulate matter, thereby reducing the particulate load on the particulate filter. Engine operating parameters that can be adjusted include spark timing, fuel injection amount, engine torque limit, and / or other operating parameters. The method 400 then returns.

[0074] The method 400 described above includes a diagnostic test for a downstream hose connection across the GPF 206, which is an intrusive diagnostic test that may include intrusive valve actuation that may be controlled by the controller 12. The intrusive valve actuation may include commanding the exhaust tuning valve to a fully open or fully closed position, regardless of how the exhaust tuning valve is otherwise controlled. In another example, the diagnostic may be performed via a non-intrusive test controlled by the controller 12 during certain engine operating conditions. For example, the controller may monitor a differential pressure during an engine operating condition where the exhaust tuning valve is commanded to a fully open position as part of exhaust tuning valve control based on a selected noise pattern. The controller may also monitor a differential pressure during an engine operating condition where the exhaust tuning valve is commanded to a fully closed position as part of exhaust tuning valve control based on a selected noise pattern. The difference between the monitored differential pressures may then be determined to determine whether the downstream hose is connected.

[0075] Now refer to Figure 7 , shows an example operational sequence 700 illustrating the operation of a DP sensor (e.g., such as Figure 2 sensor 208 shown) and an exhaust tuning valve (e.g., such as Figure 2 The intrusive test can detect a downstream hose disconnect by adjusting the exhaust tuning valve position from fully open to fully closed and obtaining a differential pressure output from the DP sensor at the two valve positions. The intrusive test period consists of a valve open period (0 to t1) and a valve closed period (t1 to t2), and a hose disconnect condition can be inferred based on a comparison of the differential pressure outputs obtained during these periods.

[0076] Figure 7 The differential pressure output of the DP sensor is shown during steady-state conditions (e.g., constant exhaust flow rate) over time during different positions of the exhaust tuning valve. The horizontal axis (x-axis) represents time, and the vertical labels t1 to t2 represent the exhaust valve opening and closing durations during engine operation. The first curve from the top shows the exhaust mass flow rate (line 702) over time, which remains relatively constant during the intrusive test period including the opening and closing durations of the exhaust tuning. The second curve (line 704) represents the exhaust tuning valve position over time (e.g., fully open from 0 to t1 and fully closed from t1 to t2). The third curve shows the differential pressure, which can be measured by the DP sensor during the intrusive test period. The dashed line 708 depicts the differential pressure measurement that can be observed when the downstream hose is intact / connected, and the solid line 708 shows the differential pressure measured when the downstream hose connection is disconnected.

[0077] As can be seen from line 708 in the third plot, when the downstream hose of the DP sensor is connected, the differential pressure output from the DP sensor does not change in response to the exhaust tuning valve moving from fully open to fully closed position. However, as shown in plot 706, when the downstream hose is disconnected and the exhaust tuning valve position is moved from fully open to fully closed, the back pressure introduced into the system causes an increase in the differential pressure measured by the DP sensor after time ti. Thus, during the exhaust tuning valve closed position when the downstream hose is disconnected (e.g., during ti to t2), a higher differential pressure is observed (e.g., line 706) compared to when the downstream hose is connected (e.g., line 708). This is because when the downstream hose is connected, the increased back pressure caused by closing the exhaust tuning valve is also measured by the downstream side of the differential pressure sensor, causing minimal or no change in the differential pressure. By contrast, when the downstream hose is disconnected, the increased back pressure is measured by the upstream side of the differential pressure sensor relative to atmospheric pressure, which does not change when the exhaust tuning valve is closed.

[0078] As discussed previously in Figure 4 , the intrusive diagnostic test to check the downstream hose connection can include an exhaust tuning valve open phase and an exhaust tuning valve closed phase. By adjusting the exhaust tuning valve from fully open to fully closed position, if the differential pressure increases (e.g., the DP sensor output from ti to t2 compared to the DP sensor output from 0 to ti), then a downstream hose disconnected condition can be inferred.

[0079] As previously mentioned, the exhaust tuning valve can be an actively controlled exhaust tuning valve. In other examples, the exhaust tuning valve can be a passive exhaust tuning valve that can be controlled by a load-bearing spring in the exhaust device, such that high exhaust flow pressure can cause the valve to open, while low exhaust flow pressure can cause the valve to remain closed.

[0080] In an exhaust system including a GPF and a DP sensor, such as the system described above with respect to Figure 2 , if the downstream hose of the DP sensor becomes disconnected and the downstream exhaust tuning valve is passive and held in a closed position, the downstream hose disconnection can need to be detected and distinguished from a deteriorated particulate filter. In the case of the exhaust tuning valve being closed and the downstream hose being disconnected or deteriorated, the increased exhaust back pressure can be caused by the closing of the tuning valve and can be sensed by the upstream hose of the DP sensor, however the downstream hose of the differential pressure sensor can sense atmospheric pressure. As a result, when the exhaust tuning valve is closed and the downstream hose is disconnected, the DP sensor can measure an increase in differential pressure, even when the GPF is missing or deteriorated, which can mimic the pressure drop measured by the DP sensor when there is a complete, non-deteriorated GPF. Figures 8 to 10An example flowchart depicting how a downstream hose disconnection can be detected without actively adjusting an exhaust tuning valve (e.g., in an exhaust system employing a passive exhaust tuning valve) is shown. The differential pressure output is compared to a threshold value to indicate degradation of a hose coupled across a particulate filter in response to how the differential pressure output is compared using an alternative method, as shown in Figure 2 In cases where the upstream hose includes an orifice, a pneumatic valve is positioned in the upstream hose, and / or a vented vacuum valve is fluidly coupled to the downstream hose, the exhaust flow differential pressure measured by the DP sensor can be used to verify the downstream hose connection, as shown.

[0081] Figure 8 A flowchart is shown illustrating a method 800 for diagnosing degradation of a downstream hose housing a differential pressure sensor, where the upstream hose has a small orifice (such as Figure 2upstream hose connection. The orifice 226 can act as a mechanical low pass filter, reducing exhaust pressure or flow pulsations, and thus resulting in a smoother signal from the DP sensor. Further, the orifice can cause a delayed or smaller pressure change to be observed on the upstream side of the differential pressure sensor when exhaust mass flow changes. At 802, the method includes determining engine operating conditions. For example, engine operating conditions can include engine speed, torque demand, boost level, engine temperature, exhaust temperature, barometric pressure, fuel octane content, fuel composition (e.g., fuel alcohol content), particulate filter load, etc. At 804, the method includes determining whether one or more entry conditions for a diagnostic test have been met, the diagnostic test verifying connection of the downstream hose to a GPF in an exhaust device. Diagnostic test entry conditions can be a set of predefined engine operating conditions that must all be met for the method 800 to proceed further, and can include air mass being within a desired test range, a steady state condition as defined by a mass air flow change being less than a threshold value, no exhaust tuning valve faults, no exhaust pressure sensor faults, exhaust being warm enough for testing (as inferred by catalyst temperature as measured by a temperature sensor such as sensor 216), engine coolant temperature being above a threshold value, vehicle not in deceleration fuel cut phase, etc. In one example, the storage medium read only memory 106 can be programmed with instructions executable by the processor 102 to verify whether the entry conditions needed for the diagnostic test are met. If the entry conditions are not met, the method 800 moves to 806 to continue to hold the current engine operating conditions. In other examples, not all entry conditions must be met for the method to proceed, e.g., a subset of the entry conditions can be met. Holding the current operating conditions can include continuing to operate the passive exhaust tuning valve 218 in a closed position if exhaust flow is relatively low and thus pressure is relatively low, or in an open position if exhaust flow is relatively high and thus pressure is relatively high. Holding the current operating conditions can further include monitoring particulate filter load based on output from the differential pressure sensor.

[0082] However, if the entry condition is determined to be satisfied at 804, the method 800 proceeds to begin a diagnostic test for checking the downstream hose connection of the cross-GPF coupled DP sensor. At 808, the method 800 measures the differential pressure Pi as an output of the differential pressure sensor. In one example, the differential pressure output data of the differential pressure sensor can be received by the controller and accumulated as a set of discrete pressure readings taken over time. At 810, the method 800 determines that a mass air flow reduction is detected. The air flow reduction can occur due to an operator requested torque change, such as due to a soft accelerator pedal event. The air flow reduction can be caused by changing the throttle position, where the throttle 62 can be operated to change the intake air provided to the combustion cylinders 30. In one example, the air flow can be measured by the mass air flow sensor 120 and / or the manifold air pressure sensor 122, which can provide MAF and MAP data to the controller 12 to calculate whether a mass air flow reduction has occurred. Alternatively, the mass air flow can be calculated as a function of manifold temperature, manifold pressure, throttle area, etc., and the mass air flow reduction is calculated by the controller 12.

[0083] At 810, if the controller determines that there is no air flow reduction (or the reduction in air flow is less than a threshold amount), the method 800 returns to 806 to continue to maintain the current engine operating condition. However, if an air flow reduction is determined at 810, the method 800 moves to 812 to measure the differential pressure P2 as an output of the differential pressure sensor, where P2 is the differential pressure measured by the differential pressure sensor after the air flow reduction occurs. More than one pressure reading can be taken during the air flow reduction. At 814, the method 800 calculates a rate of change of the differential pressure sensor output, for example, over a period of time, which can be calculated by determining the difference of P2 and Pi (and further pressure measurements) as a function of time “t”. In an example, the rate of change determined at 814 can be an absolute rate of change.

[0084] At 816, the method 800 then determines whether the rate of change of the differential pressure is less than a threshold. The threshold referred to at 816 can be a rate of change that would be expected if the downstream hose was connected. When a vehicle experiences a MAF reduction, such as during a soft accelerator pedal event, a full upstream and downstream hose connection would cause the DP sensor to sense a reduction in pressure at both the upstream side and the downstream side of the DP sensor. However, due to the orifice in the upstream hose, the upstream side of the differential pressure sensor would be exposed to changing exhaust pressure at a slower rate than the downstream side of the differential pressure sensor. Under this condition, the rate of change of the differential pressure would increase momentarily and then decrease, and thus would be above the threshold referred to at 816.

[0085] Thus, if the calculated differential pressure rate of change is not found to be less than the threshold at 816, the method 800 proceeds to 818 and concludes that the downstream hose is intact and connected to the exhaust device / downpipe downstream of the GPF. The method 800 then returns.

[0086] However, finding that the calculated differential pressure rate of change is less than the threshold at reduced MAF, it can be the result of upstream pressure reduction (due to reduced MAF during a soft accelerator pedal event) and downstream hose connection registering atmospheric pressure due to the downstream hose being disconnected. Thus, if the calculated differential pressure rate of change is found to be less than the threshold at 816, the method 800 moves to 820 and diagnoses the downstream hose of the DP sensor as disconnected from the exhaust system. The method 800 then returns.

[0087] Reference is now made to Figure 11 , showing a graph 1100 depicting the output of a differential pressure sensor coupled across a particulate filter in an exhaust device, with an orifice located in the upstream hose. The two curves depicted are time-aligned and occur simultaneously. The horizontal axis (x-axis) represents time, and the vertical markers to indicate times during which changes in exhaust mass flow during engine operation are experienced. The first curve from the top shows the differential pressure that can be measured by the DP sensor, with the upstream hose connection including the orifice 226. The dashed line 1104 depicts the differential pressure measurements that can be observed when the downstream hose is intact / connected to the exhaust system, while the solid line 1102 shows the differential pressure measured when the downstream hose connection is disconnected.

[0088] The second curve shows the changes in exhaust mass flow during engine operation. The engine can operate at high exhaust flow during to ti. At time ti, a change in mass air flow can occur (e.g., a soft accelerator pedal event), causing a reduced exhaust flow to be observed during ti to t2, as depicted by line 1106.

[0089] During high exhaust flow conditions, both the upstream and downstream hose connections, when intact, may be exposed to high exhaust pressures that can be measured by the DP sensor (e.g., line 1104 during t0 to t1). At time t1, a change in mass exhaust flow through the exhaust system may be experienced, such as during a tip-out event. This may cause only a rapid decrease in downstream pressure, while upstream pressure responds slowly due to the restriction / orifice slowing down the decompression of the upstream line. Because the DP sensor outputs differential pressure, a decrease in exhaust flow may produce a brief increase in differential pressure for each deceleration given the intact hose connection, as shown by line 1104 during t1 to t2. However, during high exhaust flow conditions when the downstream hose is disconnected, the upstream hose connection may observe a high upstream exhaust pressure, while the downstream hose connection may continue to sense atmospheric pressure, resulting in a differential pressure output from the DP sensor during t0 to t1 (shown by line 1102). At time t1, the decrease in mass exhaust flow reduces the total exhaust flow through the exhaust system, causing the upstream pressure in the upstream hose connection to decrease, while the downstream hose continues to sense atmospheric pressure. In this case, the differential pressure output of the DP sensor decreases as shown by line 1102 during time t1 to t2 to reflect the decrease in total exhaust flow at the upstream side of the sensor. Therefore, a comparison of the rate of change of differential pressure measured during the reduced exhaust flow condition can detect a downstream hose disconnection. In other words, if the difference between the DP output measured from t1 to t2 and the DP output measured from t0 to t1 is found to be less than a threshold rate of pressure change, then the disconnection can be detected as previously described. Figure 8 The downstream hose is indicated as disconnected as described at 816. In contrast, if the rate of change of the differential pressure increases and then decreases, the downstream hose is indicated as connected.

[0090] In the downstream hose diagnostic routine (e.g. Figure 8 During method 800), the output from the differential pressure sensor can be collected at various times and analyzed to determine whether the downstream hose is disconnected. In one example, Figure 11The output from the differential pressure sensor is obtained at a time ti, which represents a first pressure measurement (e.g., Pi) at the start of the off-throttle event (e.g., measured as the exhaust mass flow starts to decrease), and the output from the differential pressure sensor is obtained at a time point after ti, such as t2. Further, in some examples, the output from the differential pressure sensor can be obtained at one or more time points between ti and t2, and a rate of change of the differential pressure from ti to t2 can be calculated. Other mechanisms for monitoring the differential pressure change (or lack thereof) are possible, such as an average pressure from ti to t2. This differential pressure change is then compared to a threshold, which in one example can be based on an expected change in differential pressure with the downstream hose connected, or can be based on an expected change in differential pressure with the downstream hose disconnected. For example, as explained above, if the downstream hose is disconnected, the differential pressure will only decrease during the off-throttle event. Thus, if any increase in the differential pressure is observed followed by a decrease, the hose can be indicated as connected. In a further example, the expected differential pressure change with the hose connected can be determined based on a temporary increase in differential pressure at the time of the off-throttle and a change in exhaust mass flow, and the measured differential pressure change can be compared to the expected change, and if the measured differential pressure change is within a threshold range of the expected differential pressure change, the hose can be determined to be connected.

[0091] In this way, by monitoring the differential pressure across the GPF when a MAF change occurs, a single directional change in the output of the DP sensor can indicate that the downstream hose is disconnected, while a second directional change in the output of the DP sensor (e.g., first increasing then decreasing) can indicate that the hose is connected.

[0092] Figure 9 A flowchart is shown that illustrates an additional or alternative method 900 for diagnosing deterioration of a downstream hose that houses a differential pressure sensor, where the upstream hose has an active pneumatic valve. The method 900 describes an intrusive test that utilizes an active pneumatic valve (e.g., pneumatic valve 228) positioned in the upstream hose between the DP sensor and the exhaust passage. At 902, the method includes determining an engine operating condition as previously described with reference to Figure 8 The method determines whether one or more entry conditions for a diagnostic test have been met at 904, the diagnostic test verifying connection of the downstream hose to the GPF in the exhaust device. The diagnostic test entry conditions can be a set of predefined engine operating conditions that must be met in order for the method 900 to proceed as previously described with reference to Figure 8Further, for example, the entry condition may include high exhaust flow through the exhaust system. In one example, the storage medium read-only memory 106 may be programmed with instructions executable by the processor 102 to verify whether the entry condition required for the diagnostic test has been met. If the entry condition is not met, method 900 moves to 906 to continue maintaining the current engine operating conditions. Maintaining the current operating conditions may include continuing to operate a passive exhaust tuning valve (e.g., valve 218) in a closed position (if the exhaust flow and, therefore, pressure, is relatively low) or an open position (if the exhaust flow and, therefore, pressure, is relatively high). Maintaining the current operating conditions may further include monitoring particulate filter loading based on output from a differential pressure sensor.

[0093] At 904, if the entry conditions are determined to be met, then method 900 proceeds to begin a diagnostic test for checking the downstream hose connection of the DP sensor coupled across the GPF. At 908, method 900 maintains the pneumatic valve in the upstream hose in an open position. The pneumatic valve may be operated by a pneumatic valve as previously described. Figure 2The controller 12 described above pneumatically controls an active valve. At 910, the method 900 measures a differential pressure P1 as a differential pressure output of the differential pressure sensor. In one example, the pressure P1 can reflect more than one absolute measurement of the differential pressure output of the differential pressure sensor taken at predetermined time intervals (e.g., an average of multiple pressure measurements) and can be stored in the memory of the controller. At 912, the method 900 determines whether a mass air flow change is detected, such as a soft accelerator pedal event. In one example, the air flow can be measured by various sensors of the engine 10, such as the mass air flow sensor 120 and / or the manifold air pressure sensor 122. Alternatively, the mass air flow can be calculated as a function of manifold temperature, manifold pressure, throttle area, etc., and the mass air flow change can be calculated by the controller 12. If the controller determines that there is no air flow change at 912, the method 900 returns to 906 to continue to maintain the current engine operating condition. However, if an air flow change is determined at 912, the method 900 moves to 914 to close the pneumatic valve in the upstream hose. The pneumatic valve traps exhaust gas between the pneumatic valve and the DP sensor on the upstream side when closed. Thus, the DP sensor measures a constant pressure on the upstream side. At 916, the method 900 measures a differential pressure P2 as a differential pressure output of the differential pressure sensor. In one example, the pressure P2 can be a set of absolute differential pressure values from the DP sensor taken over a defined time period after the pneumatic valve is closed. In other examples, the pressure P2 can be an absolute value of the differential pressure output of the DP sensor taken at a predetermined time after the pneumatic valve is closed. At 918, the method 900 calculates a change in the differential pressure sensor output after the pneumatic valve adjustment. For example, the method 900 calculates a difference between the measured differential pressure P2 (e.g., an absolute value of the differential pressure output of the DP sensor taken at a certain time after the pneumatic valve is closed or measured over a defined time period) and the measured differential pressure P1 (e.g., an absolute differential pressure output of the differential pressure sensor measured just before the air flow change is determined when the pneumatic valve is open). In some examples, depending on the amount of time that has elapsed since the pneumatic valve was closed, a range of values for the pressure P2 measured after the pneumatic valve is closed can be obtained from the DP sensor. Thus, in one example, the method 900 can calculate a change in the DP sensor output at 918 by calculating a difference between various absolute values of P2 measured over a defined time period and P1 measured before the air flow change occurs when the pneumatic valve is open.

[0094] At 920, the method 900 then determines whether the calculated differential pressure change is greater than a threshold. The threshold referred to at 920 can be the change that would be expected in the event of the downstream hose being disconnected. With the pneumatic valve open, the DP sensor measures exhaust pressure upstream of the GPF, and with the pneumatic valve closed, the pneumatic valve blocks the fluid connection between the exhaust flow upstream of the GPF and the DP sensor and traps the upstream exhaust between the pneumatic valve and the DP sensor. Thus, the DP sensor measures a constant pressure on the upstream side, while on the downstream side, the DP sensor can measure a decreasing downstream exhaust pressure (e.g., due to a soft accelerator pedal condition) if the downstream hose connection of the DP sensor is intact. Thus, a change from a high exhaust flow condition to a soft accelerator pedal condition with the pneumatic valve closed will cause the differential pressure to exceed the threshold, which indicates the downstream hose as being intact and connected to the exhaust device / exhaust passage downstream of the GPF 206. Thus, if the calculated differential pressure change (P2-P1) is found to be greater than the threshold at 920, the method 900 concludes that the downstream hose is intact and connected to the exhaust device / exhaust passage downstream of the GPF 206 at 922. The method 900 then returns.

[0095] In contrast, if the downstream hose is disconnected and the DP sensor is measuring atmospheric pressure on the downstream side, with the upstream side measuring a constant pressure, the total change in pressure due to a change in MAF (e.g., a soft accelerator pedal) will cause the differential pressure output change to be less than the threshold, as both the upstream and downstream pressure measurements will remain constant after the pneumatic valve is closed. Thus, if the differential pressure change is determined not to be greater than the threshold at 920, the method 900 moves to 924 and diagnoses the downstream hose of the DP sensor as being disconnected from the exhaust system. The method 900 then returns.

[0096] In this way, by monitoring the differential pressure in the vehicle system and by actively controlling the opening and closing of the pneumatic valve in the upstream hose, a downstream hose disconnection can be diagnosed.

[0097] Figure 12 An example graph 1200 showing operational parameters that can be observed during execution of the method 900 is shown. The graph 1200 includes a curve showing differential pressure (e.g., as an output of the differential pressure sensor 208), a curve showing exhaust mass flow, and a curve showing pneumatic valve position (e.g., position of the valve 228). For each curve, time is plotted along the x-axis, and the respective value of each operational parameter is plotted along the y-axis. For the differential pressure and exhaust mass flow curves, the value of the respective operational parameter increases in the direction of the arrow.

[0098] Prior to time ti, the exhaust mass flow is relatively high, as shown by line 1206. The pneumatic valve is open, as shown by line 1208, causing the upstream side of the differential pressure sensor to be exposed to the exhaust flow / pressure upstream of the GPF. If the downstream hose is disconnected, the differential pressure measurement can be relatively high (or at least greater than zero) due to the exhaust pressure upstream of the GPF being higher than atmospheric pressure, as shown by solid line 1202. When the hose is connected, a relatively low differential pressure is measured (as shown by dashed line 1204) because both the upstream and downstream sides are exposed to similar pressures (however, depending on the load on the GPF, there can be a small or large pressure drop across the GPF, which can cause the differential pressure to be relatively small or relatively large, as shown).

[0099] At time ti, a soft accelerator pedal event occurs, causing the exhaust mass flow to decrease. In response to the decrease in exhaust mass flow, the pneumatic valve closes after time ti. As a result, exhaust gas is trapped between the valve and the upstream side of the differential pressure sensor, and the upstream side of the differential pressure sensor measures a constant pressure. In contrast, if the downstream hose is connected, the downstream side is exposed to a decreasing exhaust pressure. Thus, as shown by line 1204, the differential pressure output of the differential pressure sensor will change at least between times ti and t2 (as shown, the differential pressure increases because the trapped exhaust gas behind the pneumatic valve is at a higher pressure than the exhaust pressure downstream of the GPF as the exhaust mass flow decreases during the soft accelerator pedal).

[0100] If the downstream hose is disconnected, the differential pressure output of the differential pressure sensor will not change after the pneumatic valve closes because both the upstream and downstream sides of the differential pressure sensor are exposed to constant pressures (trapped exhaust gas behind the pneumatic valve and atmospheric pressure, respectively). Thus, the differential pressure does not change after the pneumatic valve is closed for the disconnected hose, as shown by line 1202.

[0101] During a downstream hose diagnostic routine (e.g., method 900 of FIG. 9), the output from the differential pressure sensor can be collected at various times and analyzed to determine whether the downstream hose is disconnected. In one example, the output from the differential pressure sensor can be collected at times ti, t2, and t3. Figure 9 Figure 12 ​the output from the differential pressure sensor at a time tl (which represents a first pressure measurement (e.g., PI) at or just before the pneumatic valve is closed) and at a time point after tl, such as t2. In other examples, PI can be obtained (e.g., after tl but before t2) once the pneumatic valve is closed, although the exhaust mass flow is still changing. Further, in some examples, the output from the differential pressure sensor can be obtained at one or more time points between tl and t2, and a rate of change of the differential pressure from tl to t2 can be calculated. Other mechanisms for monitoring the change (or lack of change) in differential pressure are possible, such as an average pressure from tl to t2. The differential pressure change is then compared to a threshold, which in one example can be based on an expected change in differential pressure with the downstream hose connected, or can be based on an expected change in differential pressure with the downstream hose disconnected. For example, as explained above, with the downstream hose disconnected, the differential pressure will not change appreciably after the pneumatic valve is closed. Thus, if any differential pressure change is observed, the hose can be indicated as connected. In other examples, although less than the threshold, the differential pressure change can still indicate a disconnected hose. In still further examples, the expected change in differential pressure with the hose connected can be determined based on the differential pressure and the exhaust mass flow change at the time the valve is closed, and the measured differential pressure change can be compared to the expected change, and if the measured differential pressure change is within a threshold range of the expected differential pressure change, the hose can be determined to be connected.

[0102] Figure 10 Further additional or alternative methods of diagnosing a disconnected downstream hose are shown. Turning now to Figure 10 , a flowchart is shown that illustrates a method 1000 for diagnosing deterioration of a downstream hose housing a differential pressure sensor, where the downstream hose has an active vented vacuum valve. The method 1000 describes another invasive test that utilizes an active vented vacuum valve (e.g., vented vacuum valve 230) fluidly connected to the downstream hose between the DP sensor and the exhaust passage. At 1002, the method 1000 determines the engine operating conditions as previously described with reference to Figures 8 to 9 At 1004, the method determines whether one or more entry conditions of a diagnostic test have been met, the diagnostic test verifying the connection of the downstream hose to the GPF in the exhaust device. The diagnostic test entry conditions can be a set of pre-defined engine operating conditions that must be met in order for the method 1000 to proceed as previously described with reference to Figures 8 to 9The further advancement, e.g., into condition, can include a high exhaust flow through the exhaust system 200. In one example, the storage medium read-only memory 106 can be programmed with instructions executable by the processor 102 to check whether the entry condition required for the diagnostic test is met. If the entry condition is not met, then the method 1000 moves to 1006 to continue to maintain the current engine operating condition. Maintaining the current operating condition can include continuing to operate the passive exhaust tuning valve 218 in the closed position if the exhaust flow is relatively low and thus the pressure is relatively low or in the open position if the exhaust flow is relatively high and thus the pressure is relatively high. Maintaining the current operating condition can further include monitoring the particulate filter load based on the output from the differential pressure sensor.

[0103] At 1004, if the entry condition is determined to be met, then the method 1000 begins a diagnostic test for checking the downstream hose connection of the DP sensor coupled across the GPF. At 1008, the method 1000 measures the differential pressure by taking the output from the DP sensor prior to the vent vacuum valve adjustment. The vent vacuum valve can be positioned in the downstream hose such that exhaust flow into the downstream hose can pass via the vent vacuum valve for the DP sensor to sense the downstream pressure of the exhaust flow. In one example, the output of the differential pressure sensor can be received by the controller and stored as a set of discrete pressure readings taken over time. At 1010, the method 1000 advances to check the downstream hose connection of the DP sensor by vent vacuum valve adjustment, where adjusting the vent vacuum valve can include moving the vent vacuum valve as indicated. Figure 2 At 1012, the method 1000 includes adjusting the vent vacuum valve such that the vent vacuum valve is closed on the exhaust system side and no longer allows exhaust flow through the exhaust passage into the downstream hose to pass via the vent vacuum valve to the DP sensor. Additionally at 1014, adjusting the vent vacuum valve includes venting the vent vacuum valve to atmosphere on the DP sensor side such that the DP sensor now measures atmospheric pressure at the downstream hose end. At 1016, the method 1000 measures the DP from the DP sensor after the vent vacuum valve adjustment, where the adjusted vent vacuum valve blocks downstream exhaust flow on one end and allows the DP sensor to measure atmospheric pressure on the other end.

[0104] At 1018, the method 1000 calculates the change in output of the differential pressure sensor before and after adjustment of the vent vacuum valve. For example, the difference between the differential pressure measured when the vent vacuum valve is opened to allow exhaust flow in the downstream hose (from step 1008) and the differential pressure measured after the vent vacuum valve has been adjusted to block exhaust flow downstream and the DP sensor is vented to atmosphere (from step 1016) is calculated. At 1020, the method 1000 then determines whether the calculated change in differential pressure is greater than a threshold. The threshold referred to at 1020 can indicate a change in DP sensor output below which the downstream hose will be indicated as disconnected. Under conditions of high exhaust flow through the vehicle (e.g., an accelerator pedal event), both the upstream and downstream hose connections will reflect high exhaust flow pressure upstream and downstream of the GPF, respectively, when intact. However, upon intrusive adjustment of the vent vacuum valve position to block exhaust flow downstream during an accelerator pedal event and venting the DP sensor to atmosphere, the DP sensor can measure exhaust pressure upstream at the upstream end and atmospheric pressure at the downstream end, causing a change in differential pressure above the threshold. Thus, if the calculated change in differential pressure is found to be greater than the threshold at 1020, the method 1000 concludes at 1022 that the downstream hose is intact and connected to the exhaust device / exhaust passage downstream of the GPF 206. However, if the calculated change is not greater than the threshold at 1020, the method 1000 moves to 1024 and diagnoses the downstream hose of the DP sensor as disconnected from the exhaust system. The method 1000 then returns.

[0105] Figure 13 An example graph 1300 showing operational parameters that can be observed during execution of the method 1000 is shown. The graph 1300 includes a plot showing differential pressure (e.g., as output of the differential pressure sensor 208), a plot showing exhaust mass flow, and a plot showing vent vacuum valve position (e.g., position of the valve 230). For each plot, time is plotted along the x-axis, and the respective value of each operational parameter is plotted along the y-axis. For the differential pressure and exhaust mass flow plots, the value of the respective operational parameter increases in the direction of the arrow.

[0106] Before time ti, and also after time ti, the exhaust mass flow is relatively high, and no appreciable change occurs, as shown by line 1306. The vent vacuum valve opens, as shown by line 1308, causing the upstream side of the differential pressure sensor to be exposed to the exhaust flow / pressure upstream of the GPF, and the downstream side of the differential pressure sensor to be exposed to the exhaust flow / pressure downstream of the GPF (if the downstream hose is connected) or to atmosphere (if the downstream hose is disconnected). If the downstream hose is disconnected, then the differential pressure measurement can be relatively high (or at least greater than zero) due to the exhaust pressure upstream of the GPF being higher than atmospheric pressure, as shown by solid line 1302. When the hose is connected, a relatively low differential pressure is measured (as shown by dashed line 1304) because both the upstream and downstream sides are exposed to similar pressures (however, depending on the load on the GPF, there can be a small or large pressure drop across the GPF, which can cause a relatively small or larger differential pressure as shown in the figure).

[0107] At time ti, the vent vacuum valve closes, causing the downstream side of the differential pressure sensor to be exposed to atmosphere. If the downstream hose is connected, then closing the vent vacuum valve will cause the downstream side of the differential pressure sensor to transition from being exposed to the exhaust pressure downstream of the GPF to being exposed to atmospheric pressure. Thus, as shown by line 1304, the differential pressure output by the differential pressure sensor will change (as shown, the differential pressure increases because the exhaust pressure measured by the upstream side of the differential pressure sensor is at a higher pressure than atmospheric pressure) at least between times ti and t2.

[0108] If the downstream hose is disconnected, then after the vent vacuum valve closes, the differential pressure output by the differential pressure sensor will not change appreciably because the downstream side of the differential pressure sensor is still exposed to atmospheric pressure, and the upstream side is exposed to the exhaust pressure upstream of the GPF, which does not change due to steady state engine operation. Thus, for a disconnected hose, the differential pressure does not change after the vent vacuum valve is closed, as shown by line 1302.

[0109] During a downstream hose diagnostic routine (e.g., method 1000 of FIG. 1), the output from the differential pressure sensor can be collected at various times and analyzed to determine whether the downstream hose is disconnected. In one example, the output from the differential pressure sensor can be collected at times ti and t2, as shown in FIG. 13. Figure 10 Figure 13 ​the output from the differential pressure sensor at a time tl (which represents a first pressure measurement at or just prior to the time the vent vacuum valve is closed (e.g., PI)) and at a point in time after tl, such as t2. In other examples, PI can be obtained prior to tl. Further, in some examples, the output from the differential pressure sensor can be obtained at tl and t2, and at one or more points in time between tl and t2, and the differential pressure change from tl to t2 can be calculated. Other mechanisms for monitoring the change (or lack of change) in differential pressure are possible, such as the average pressure from tl to t2. The differential pressure change is then compared to a threshold, which in one example can be based on the expected differential pressure change with the downstream hose connected, or can be based on the expected differential pressure change with the downstream hose disconnected. For example, as explained above, if the downstream hose is disconnected, the differential pressure will not change appreciably after the vent vacuum valve is closed. Thus, if any change in differential pressure is observed, the hose can be indicated as connected. In other examples, a differential pressure change less than a threshold can indicate the hose is disconnected. In still further examples, the expected differential pressure change with the hose connected can be determined based on the differential pressure at the time the valve is closed and the exhaust mass flow, and the measured differential pressure change can be compared to the expected change, and if the measured differential pressure change is within a threshold range of the expected change in differential pressure, the hose can be determined to be connected.

[0110] In this way, in vehicle systems employing passive exhaust tuning valves, the differential pressure change during a change in exhaust flow condition can be used to indicate a downstream hose disconnect condition. Further, in systems employing active exhaust tuning valves, adjusting the exhaust tuning valve position from open to closed and detecting a differential pressure change can indicate a downstream hose disconnect. When a hose disconnect is not indicated, monitoring the differential pressure across the particulate filter and estimating it against the expected pressure at a given time during engine operation can indicate a filter degradation. Thus, by monitoring the differential pressure sensor output, a particulate filter degradation condition can be reliably and accurately detected and distinguished from a hose disconnect and / or DP sensor degradation condition.

[0111] The technical effect of performing a differential pressure hose diagnostic routine in an exhaust system including an active exhaust tuning valve or a system including a passive exhaust tuning valve in combination with one or more of an orifice, a pneumatic valve, or a vent vacuum valve is that a downstream hose disconnect and / or filter absence or degradation coupled across the differential pressure sensor can be identified. By measuring the differential pressure output from the DP sensor, a downstream hose connection that can have become disconnected can be distinguished from a degradation of the particulate filter during engine operation. Overall, the accuracy and reliability of vehicle diagnostics can be improved.

[0112] In one example, a method for an engine includes, during a condition in which a differential pressure sensor is exposed to varying exhaust pressure, indicating degradation of a hose coupled across a particulate filter in an exhaust system in response to a differential pressure change measured by the differential pressure sensor differing from an expected change, the differential pressure sensor positioned in the hose and the particulate filter positioned upstream of an exhaust tuning valve. In a first example of the method, the exhaust tuning valve is coupled across a muffler positioned in an exhaust passage of the exhaust system downstream of a connection point, the connection point including a location at which an outlet of the hose is configured to be coupled to the exhaust passage or the particulate filter. In a second example of the method, the second example optionally includes the first example, the condition in which the differential pressure sensor is exposed to varying exhaust pressure can include a decrease in exhaust mass flow through the exhaust system, and indicating degradation of the hose in response to the differential pressure change differing from the expected change can include indicating degradation in response to the differential pressure change being less than the expected change. In a third example of the method, the third example optionally includes one or both of the first example and the second example, the condition in which the differential pressure sensor is exposed to varying exhaust pressure can include a decrease in exhaust mass flow through the exhaust system with a constant exhaust pressure exposed to an upstream side of the differential pressure sensor, and indicating degradation of the hose in response to the differential pressure change differing from the expected change can include indicating degradation in response to the differential pressure change being less than the expected change. In a fourth example of the method, the fourth example optionally includes one or more or each of the first example through the third example, the method further includes, in response to detecting the decrease in exhaust mass flow, closing a valve coupled in an upstream portion of the hose so as to expose the upstream side of the differential pressure sensor to the constant exhaust pressure. In a fifth example of the method, the fifth example optionally includes one or more or each of the first example through the fourth example, the condition in which the differential pressure sensor is exposed to varying exhaust pressure can include adjusting a position of a vent vacuum valve positioned in a downstream portion of the hose to expose a downstream side of the differential pressure sensor to atmospheric air, and indicating degradation of the hose in response to the differential pressure change differing from the expected change can include indicating degradation in response to the differential pressure change being less than the expected change. In a sixth example of the method, the sixth example optionally includes one or more or each of the first example through the fifth example, the expected change is based on one or more of the differential pressure before the differential pressure sensor is exposed to varying exhaust pressure and the exhaust mass flow when the exhaust pressure is constantly varying. In a seventh example of the method, the seventh example optionally includes one or more or each of the first example through the sixth example, the method can further include, in response to the change being within a threshold range of the expected change, indicating that the hose is not degraded. In an eighth example of the method, the eighth example optionally includes one or more or each of the first example through the seventh example, the method further includes, when the hose is not degraded, performing a particulate filter diagnostic routine in response to a particulate filter diagnostic condition being satisfied.In a ninth example of the method, the ninth example optionally includes one or more or each of the first through eighth examples, executing the particulate filter diagnostic routine can include measuring a filter differential pressure across the particulate filter with the differential pressure sensor; and indicating degradation of the particulate filter if the filter differential pressure is outside of an expected filter differential pressure range. In a tenth example of the method, the tenth example optionally includes one or more or each of the first through ninth examples, the method further includes, in response to indicating degradation of the hose, notifying an operator and / or setting a diagnostic code, and not executing the particulate filter diagnostic routine when the hose is degraded even if the particulate filter diagnostic condition is satisfied. In an eleventh example of the method, the eleventh example optionally includes one or more or each of the first through tenth examples, the method can further include adjusting one or more engine operating parameters in response to indicating degradation of the hose.

[0113] Another example provides a system including a particulate filter coupled in an exhaust passage; a differential pressure sensor; an upstream hose coupling the differential pressure sensor to the exhaust passage upstream of the particulate filter; a downstream hose coupling the differential pressure sensor to the exhaust passage downstream of the particulate filter; a diagnostic valve positioned in the upstream hose; an exhaust tuning valve coupled across a muffler positioned in the exhaust passage downstream of the particulate filter and configured to open in response to exhaust pressure being above a threshold value; and a controller storing instructions executable to, in response to a command to perform a diagnosis of the downstream hose, close the diagnostic valve and indicate degradation of the downstream hose based on output from the differential pressure sensor as exhaust pressure in the exhaust system changes. In a first example of the method, the command to perform the diagnosis of the downstream hose is in response to an operator off accelerator pedal event in which exhaust pressure in the exhaust system decreases, and the controller stores instructions executable to notify an operator, set a diagnostic code, and / or adjust one or more engine operating parameters in response to indicating degradation of the hose. In a second example of the method, the second example optionally includes the first example, the controller is configured to indicate degradation of the downstream hose in response to a differential pressure change measured by the differential pressure sensor during a duration after closing the diagnostic valve being less than a threshold change. In a third example of the method, the third example optionally includes one or both of the first and second examples, the controller stores instructions executable to: indicate that the hose is not degraded in response to the change being greater than the threshold change; when the hose is not degraded, execute a particulate filter diagnostic routine in response to a particulate filter diagnostic condition being satisfied, the particulate filter diagnostic routine including measuring a third differential pressure across the particulate filter with the differential pressure sensor; and indicating degradation of the particulate filter if the third differential pressure is outside of an expected differential pressure range; and when the hose is degraded, not executing the particulate filter diagnostic routine even if the particulate filter diagnostic condition is satisfied.

[0114] Another example provides a system including a particulate filter coupled in an exhaust passage; a differential pressure sensor; an upstream hose coupling the differential pressure sensor to the exhaust passage upstream of the particulate filter; a downstream hose coupling the differential pressure sensor to the exhaust passage downstream of the particulate filter; a vented vacuum valve positioned in the downstream hose; an exhaust tuning valve coupled across a muffler positioned in the exhaust passage downstream of the particulate filter and configured to open in response to exhaust pressure being above a threshold value; and a controller storing instructions executable to: in response to a command to perform a diagnosis of the downstream hose, adjust a position of the vented vacuum valve to expose a downstream side of the differential pressure sensor to atmosphere, and based on an output from the differential pressure sensor after adjusting the vented vacuum valve position indicating degradation of the downstream hose. In a first example of the method, the command to perform the diagnosis of the downstream hose is in response to a steady state condition of exhaust mass flow in the exhaust system being above a threshold mass flow, and the controller stores instructions executable to indicate degradation of the hose to an operator, set a diagnostic code, and / or adjust one or more engine operating parameters. In a second example of the method, optionally including the first example, the controller is configured to indicate degradation of the downstream hose in response to a differential pressure measured by the differential pressure sensor during a duration after adjusting the vented vacuum valve position being less than a threshold change. In a third example of the method, optionally including one or both of the first and second examples, the controller stores instructions executable to: in response to the change being greater than the threshold change, indicate that the hose is not degraded; when the hose is not degraded, perform a particulate filter diagnostic routine in response to a particulate filter diagnostic condition being met, the particulate filter diagnostic routine including measuring a third differential pressure across the particulate filter with the differential pressure sensor; and if the third differential pressure is outside of an expected differential pressure range, indicate degradation of the particulate filter; and when the hose is degraded, not perform the particulate filter diagnostic routine even if the particulate filter diagnostic condition is met.

[0115] Another example provides a method including, in response to a difference between a first differential pressure and a second differential pressure being greater than a threshold indicating deterioration of a hose coupled across a particulate filter, the first differential pressure measured by a differential pressure sensor positioned in the hose in response to a downstream exhaust tuning valve being fully open, the second differential pressure measured by the differential pressure sensor in response to the exhaust tuning valve being fully closed. In a first example of the method, the exhaust tuning valve is coupled across a muffler positioned in an exhaust passage of an exhaust system downstream of a connection point, the connection point including a location at which an outlet of the hose is configured to be coupled to the exhaust passage or the particulate filter. A second example of the method optionally includes the first example and further includes wherein the first differential pressure and the second differential pressure are each measured in response to a hose diagnostic condition being satisfied, and further includes adjusting the exhaust tuning valve based on an operator prescribed noise pattern when the hose diagnostic condition is not satisfied. In a third example of the method, the third example optionally includes one or both of the first example and the second example, and the method further includes, in response to the difference being less than the threshold, indicating that the hose is not deteriorated. A fourth example of the method optionally includes one or more or each of the first example through the third example, and further includes performing a particulate filter diagnostic routine in response to a particulate filter diagnostic condition being satisfied when the hose is not deteriorated. A fifth example of the method optionally includes one or more or each of the first example through the fourth example, and further includes wherein performing the particulate filter diagnostic routine can include measuring a third differential pressure across the particulate filter with the differential pressure sensor; and indicating deterioration of the particulate filter if the third differential pressure is outside of an expected differential pressure range. A sixth example of the method optionally includes one or more or each of the first example through the fifth example, and further includes notifying an operator and / or setting a diagnostic code in response to indicating deterioration of the hose, and not performing the particulate filter diagnostic routine when the hose is deteriorated even if the particulate filter diagnostic condition is satisfied. A seventh example of the method optionally includes one or more or each of the first example through the sixth example, and further includes adjusting one or more engine operating parameters in response to indicating deterioration of the hose.

[0116] Another example provides a system for an engine including a particulate filter coupled in an exhaust passage; a differential pressure sensor; an upstream hose coupling the differential pressure sensor to the exhaust passage upstream of the particulate filter; a downstream hose coupling the differential pressure sensor to the exhaust passage downstream of the particulate filter; an exhaust tuning valve coupled across a muffler positioned in the exhaust passage downstream of the particulate filter; and a controller storing instructions executable to selectively adjust a position of the exhaust tuning valve based on an operator-selected noise mode; and in response to a command to perform a diagnosis of the downstream hose, adjust the position of the exhaust tuning valve to a fully open position and a fully closed position, and indicate degradation of the downstream hose based on output from the differential pressure sensor while the exhaust tuning valve is in the fully open position and while the exhaust tuning valve is in the fully closed position. In a first example of the system, the controller stores instructions executable to adjust the position of the exhaust tuning valve to a first position based on the operator-selected noise mode during a first engine speed and load condition; and in response to the command to perform the diagnosis of the downstream hose during the first engine speed and load condition, adjust the position of the exhaust tuning valve away from the first position to the fully open position. A second example of the system optionally includes the first example and further includes wherein the controller stores instructions executable to adjust the position of the exhaust tuning valve to the fully open position and measure a first average differential pressure with the differential pressure sensor while the exhaust tuning valve is in the fully open position; adjust the position of the exhaust tuning valve to the fully closed position and measure a second average differential pressure with the differential pressure sensor while the exhaust tuning valve is in the fully closed position; and indicate degradation of the downstream hose in response to a difference between the first average differential pressure and the second average differential pressure being greater than a threshold value. A third example of the system optionally includes one or more or both of the first example and the second example and further includes wherein the controller stores instructions executable to indicate that the hose is not degraded in response to the difference being less than the threshold value; and when the hose is not degraded, perform a particulate filter diagnostic routine in response to a particulate filter diagnostic condition being satisfied, the particulate filter diagnostic routine including measuring a third differential pressure across the particulate filter with the differential pressure sensor; and indicating degradation of the particulate filter if the third differential pressure is outside of an expected differential pressure range. A fourth example of the system optionally includes one or more or each of the first through third examples and further includes wherein the controller stores instructions executable to not perform the particulate filter diagnostic routine when the hose is degraded even if the particulate filter diagnostic condition is satisfied. A fifth example of the system optionally includes one or more or each of the first through fourth examples and further includes wherein the controller stores instructions executable to notify an operator, set a diagnostic code, and / or adjust one or more engine operating parameters in response to indicating degradation of the hose.

[0117] Another example provides a method that includes, in response to a command to perform a diagnosis of a downstream hose that couples a differential pressure sensor to an exhaust passage downstream of a particulate filter, coupling an exhaust tuning valve across a muffler positioned in the exhaust passage downstream of the particulate filter based on outputs from the differential pressure sensor to indicate degradation of the downstream hose when the exhaust tuning valve is fully open and when the exhaust tuning valve is fully closed; when the downstream hose is not indicated to be degraded, and in response to a particulate filter diagnostic condition being satisfied, performing a particulate filter diagnostic routine to indicate degradation of the particulate filter based on outputs from the differential pressure sensor and independent of the exhaust tuning valve position; and when the downstream hose is indicated to be degraded, and in response to the particulate filter diagnostic condition being satisfied, delaying performance of the particulate filter diagnostic routine until the downstream hose is no longer indicated to be degraded. A first example of the method can include selectively adjusting the position of the exhaust tuning valve based on an operator-selected noise mode. A second example of the method optionally includes the first example, and further includes, wherein indicating degradation of the downstream hose based on the outputs from the differential pressure sensor when the exhaust tuning valve is fully open and when the exhaust tuning valve is fully closed includes determining a difference between a first average differential pressure measured in response to the exhaust tuning valve being fully open and a second average differential pressure measured in response to the exhaust tuning valve being fully closed, and indicating degradation when the difference is greater than a threshold difference. A third example of the method optionally includes one or more or both of the first example and the second example, and further includes indicating degradation of an upstream hose that couples the differential pressure sensor to the exhaust passage upstream of the particulate filter in response to a negative differential pressure measured by the differential pressure sensor. A fourth example of the method optionally includes one or more or each of the first example through the third example, and further includes adjusting one or more engine parameters in response to indicating degradation of the downstream hose. A fifth example of the method optionally includes one or more or each of the first example through the fourth example, and further includes notifying an operator and / or setting a diagnostic code in response to indicating degradation of the downstream hose.

[0118] Note that the example control and estimation routines included herein can be used with various 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 a control system comprising a controller that combines 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 actions, operations, and / or functions illustrated can be performed in the manner shown, in parallel, or in some cases omitted. Likewise, the order of processing is not essential for achieving the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and / or functions can be repeated, deleted, added, modified, or performed in a different order depending on the particular strategy used. Further, the described actions, operations and / or functions can graphically represent code to be programmed into non-transitory memory of a computer readable storage medium of an engine control system, where the described actions are carried out by executing the instructions of the controller in a system comprising various engine hardware components.

[0119] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be taken in a limiting sense, as numerous 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 nonobvious combinations and subcombinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or properties now known or later learned.

[0120] The appended claims particularly point out certain combinations and subcombinations considered to be novel and nonobvious. These claims can refer to "an" element or "a first" element or equivalent thereof. Such claims should be understood to include one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of disclosed features, functions, elements, and / or properties can be claimed through amendment of the claims or presentation of additional claims in the application or in a continuation, division, or continuation-in-part application of the application. Such additional claims can be directed to discoveries or obvious aspects of the subject matter disclosed.

Claims

1. A method comprising: indicating degradation of a hose coupled across a particulate filter in an exhaust system, in response to a change in differential pressure measured by the differential pressure sensor being different than an expected change during a condition in which the differential pressure sensor is exposed to varying exhaust pressure, the differential pressure sensor being positioned in the hose and the particulate filter being positioned upstream of an exhaust tuning valve; and Wherein indicating degradation of the hose in response to the change in the differential pressure being different from the expected change includes indicating degradation in response to the change in the differential pressure being less than the expected change.

2. The method of claim 1 , wherein the exhaust tuning valve is coupled across a muffler positioned in an exhaust passage of the exhaust system downstream of a connection point including a location where an outlet of the hose is configured to couple to the exhaust passage or the particulate filter. 3 . The method of claim 1 , wherein the condition in which the differential pressure sensor is exposed to a varying exhaust pressure includes a decrease in exhaust mass flow through the exhaust system. 4 . The method of claim 1 , wherein the condition in which the differential pressure sensor is exposed to varying exhaust pressure comprises a decrease in exhaust mass flow through the exhaust system when an upstream side of the differential pressure sensor is exposed to a constant exhaust pressure. 5 . The method of claim 4 , further comprising closing a valve coupled in an upstream portion of the hose to expose the upstream side of the differential pressure sensor to a constant exhaust pressure in response to detecting a decrease in the exhaust mass flow rate.

6. The method of claim 1 , wherein exposing the differential pressure sensor to the condition of varying exhaust pressure comprises adjusting a position of a vent vacuum valve positioned in a downstream portion of the hose to expose a downstream side of the differential pressure sensor to atmosphere, and wherein indicating degradation of the hose in response to the differential pressure change being different than the expected change comprises indicating degradation in response to the differential pressure change being less than the expected change. 7 . The method of claim 1 , wherein the expected change is based on one or more of the differential pressure before the differential pressure sensor is exposed to the changing exhaust pressure and the exhaust mass flow rate at the time of the exhaust pressure change. 8 . The method of claim 1 , further comprising indicating that the hose is not degraded in response to the change being within a threshold range of the expected change, and in response to the hose not being degraded, executing a particulate filter diagnostic routine in response to a particulate filter diagnostic condition being met.

9. The method of claim 8, wherein executing the particulate filter diagnostic routine comprises: measuring a filter differential pressure across the particulate filter with the differential pressure sensor; as well as If the filter differential pressure is outside an expected filter differential pressure range, degradation of the particulate filter is indicated.

10. The method of claim 8, further comprising notifying an operator and / or setting a diagnostic code in response to indicating degradation of the hose, and not executing the particulate filter diagnostic routine when the hose is degraded even if the particulate filter diagnostic conditions are met. 11 . The method of claim 1 , further comprising adjusting one or more engine operating parameters in response to indicating degradation of the hose.

12. A system for an engine, comprising: a particulate filter coupled in the exhaust passage; Differential pressure sensor; an upstream hose coupling the differential pressure sensor to the exhaust passage upstream of the particulate filter; a downstream hose coupling the differential pressure sensor to the exhaust passage downstream of the particulate filter; a diagnostic valve positioned in the upstream hose; an exhaust tuning valve coupled across a muffler positioned in the exhaust passage downstream of the particulate filter and configured to open in response to exhaust pressure being above a threshold; as well as A controller storing instructions executable by the controller to: The diagnostic valve is closed in response to a command to perform a diagnosis of the downstream hose, and degradation of the downstream hose is indicated in response to a change in differential pressure measured from the differential pressure sensor that differs from an expected change when exhaust pressure in the exhaust system changes.

13. The system of claim 12 , wherein the command to perform the diagnostic of the downstream hose is responsive to an operator tip-out event in which exhaust pressure in the exhaust system decreases, and wherein the controller stores instructions executable to notify an operator, set a diagnostic code, and / or adjust one or more engine operating parameters in response to indicating degradation of the hose.

14. The system of claim 12, wherein the controller is configured to indicate degradation of the downstream hose in response to a change in differential pressure measured by the differential pressure sensor being less than a threshold change during a duration after closing the diagnostic valve.

15. The system of claim 14, wherein the controller stores instructions executable to: In response to the change being greater than the threshold change, indicating that the hose is not degraded; When the hose is not degraded, in response to a particulate filter diagnostic condition being met, executing a particulate filter diagnostic routine, the particulate filter diagnostic routine including measuring a third differential pressure across the particulate filter with the differential pressure sensor; and indicating degradation of the particulate filter if the third differential pressure is outside an expected differential pressure range; and When the hose is degraded, the particulate filter diagnosis routine is not executed even if the particulate filter diagnosis condition is satisfied.

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