Method and system for verifying oxygen sensor connection

Abstract

The invention provides a method and a system for verifying oxygen sensor connection. Systems and methods for detecting and compensating for erroneous wiring of an oxygen sensor of a cylinder bank of an engine are disclosed. In one example, a fuel control parameter is monitored to determine whether the fuel control parameter diverges to a fuel control threshold. If so, the controller may switch to adjust which cylinder's equivalence ratio in response to the output of the particular oxygen sensor.

Description

TECHNICAL FIELD

[0001] The present specification relates to systems and methods for verifying oxygen sensor connections of an engine. The methods can be particularly useful for V8 engines. BACKGROUND

[0002] Closed loop fuel control improves the accuracy of engine air-fuel control. Many closed loop fuel control systems apply a single universal exhaust gas oxygen (UEGO) sensor as a feedback sensor for closed loop fuel control of a cylinder group (e.g., four cylinders sharing a common cylinder head). The single oxygen sensor provides feedback for adjusting the air-to-fuel ratio or equivalence ratio of the cylinder group. The cylinder group can also share a common exhaust manifold. The single oxygen sensor can be exposed to a mixture of gases from all of the cylinders sharing the common exhaust manifold.

[0003] On a cross-plane crankshaft V8 engine, cylinder firings can be unevenly spaced at 90°, 180°, 270°, 180° cylinder firing intervals. The uneven firing intervals can cause the residence time of exhaust pulses between cylinders (of the same cylinder group) at the oxygen sensor to vary. When a single oxygen sensor is used for each cylinder group on a cross-plane crankshaft V8, the difference in residence time can degrade the ability of air-to-fuel ratio imbalance diagnostics. Air-to-fuel ratio imbalance diagnostics and fuel control can be addressed by adding a second oxygen sensor on each cylinder group. However, a miswire of the same cylinder group oxygen sensors can be detrimental to fuel control (e.g., feedback control instability) and emissions. SUMMARY

[0004] The inventors herein have recognized the above-referenced shortcomings and have developed a method for operating an engine, the method comprising: monitoring exhaust of a first set of cylinders of a cylinder group of the engine via a first oxygen sensor; monitoring exhaust of a second set of cylinders of the cylinder group via a second oxygen sensor; and switching a cylinder associated with the first set of cylinders and switching a cylinder associated with the second set of cylinders in response to an indication of a miswire of one of the first oxygen sensor and the second oxygen sensor.

[0005] By switching a cylinder associated with the first set of cylinders and switching a cylinder associated with the second set of cylinders in response to an indication of a miswire of one of the first oxygen sensor and the second oxygen sensor, the likelihood of exceeding a threshold emissions level during operation of the fuel control system can be reduced.

[0006] This specification offers several advantages. In particular, the method reduces engine air-fuel ratio variations and improves the ability to diagnose air-fuel ratio imbalances. Additionally, the method can correct incorrect oxygen sensor wiring without requiring rewiring. Furthermore, the method can be applied to different fuel control strategies.

[0007] The above and other advantages and features of this specification will become readily apparent when understood alone or in conjunction with the accompanying drawings, based on the following detailed description.

[0008] It is understood that the above description of the invention is provided to present a series of concepts further described in the detailed embodiments in a simplified form. This is not intended to identify key features of the claimed subject matter, the scope of which is uniquely defined by the claims appended to the detailed embodiments. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0009] The advantages described herein will be more fully understood when read, either alone or with reference to the accompanying drawings, by reading examples of embodiments referred to herein as specific implementations, in which: Figure 1 This is a schematic diagram of a single cylinder in an engine; Figure 2 This is a schematic diagram of an eight-cylinder engine; Figures 3 to 5 A predictive example of operational sequencing for diagnosing engine operation is shown; and Figure 6 A flowchart of an example method for operating an engine is shown. Detailed Implementation

[0010] This specification relates to the operation of a fuel control system for diagnosing an internal combustion engine. A fuel-injected engine may include one oxygen sensor for each group of two cylinders and fuel injectors. The engine wiring harness may include wires and connectors for each oxygen sensor. To control the financial costs of the engine control system, the connectors for the oxygen sensors in all engines may be identical. Furthermore, because the oxygen sensors in the cylinder banks may be adjacent to each other, wiring from the first oxygen sensor can be connected to a connector that leads to the controller input of the second oxygen sensor. Similarly, wiring from the second oxygen sensor can be connected to a connector that leads to the controller input of the first oxygen sensor. Therefore, it is possible to incorrectly wire the engine's oxygen sensors to the engine controller. However, the method described herein provides a way to correct incorrect wiring without having to move the connectors or send the vehicle for repair. Instead, the controller makes internal adjustments to compensate for the incorrectly wired oxygen sensors.

[0011] like Figure 1 The internal combustion engine shown can operate as described herein. In one example, the method described herein can be applied to, for example... Figure 2 The V8 engine shown is an example. The engine can be like... Figures 3 to 5 The response is shown in the figure. Figure 6 The document illustrates a method for operating and diagnosing the operation of an engine fuel system.

[0012] refer to Figure 1 Internal combustion engine 10 (including multiple cylinders, Figure 1 One of the cylinders shown is controlled by an electronic engine controller 12. The engine 10 includes a combustion chamber 30 and cylinder walls 32, with a piston 36 positioned within the cylinder walls and connected to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 includes a pinion shaft 98 and a pinion 95. The pinion shaft 98 selectively advances the pinion 95 to engage the ring gear 99. The starter 96 can be directly mounted to the front or rear of the engine. In some examples, the starter 96 can selectively supply torque to the crankshaft 40 via a chain. In one example, the starter 96 is in a basic state when not engaged with the engine crankshaft. The combustion chamber 30 is shown communicating with the intake manifold 44 and exhaust manifold 48 via corresponding intake valves 52 and exhaust valves 54. Each intake and exhaust valve can be operated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 can be determined by an intake cam sensor 55. The position of the exhaust cam 53 can be determined by the exhaust cam sensor 57.

[0013] A direct fuel injector 66 is shown positioned to inject fuel directly into cylinder 35, which is referred to as direct injection by those skilled in the art. The fuel injector 66 delivers liquid fuel in proportion to the voltage pulse width or fuel injector pulse width of a signal from controller 12. Fuel is delivered to the fuel injector 66 via a fuel system (not shown), which includes a fuel tank, a fuel pump, and a fuel rail (not shown). In other examples, fuel may be injected into each cylinder via a port fuel injector or via a combination of a port fuel injector and a direct fuel injector. Thus, an engine may include an actual total number of fuel injectors equal to the actual total number of cylinders, or alternatively, an engine may have two fuel injectors per cylinder. Additionally, an intake manifold 44 is shown in communication with an optional electronic throttle valve 62, which adjusts the position of the throttle plate 64 to control airflow from the intake port 42 to the intake manifold 44. In some examples, the throttle body 62 and the throttle plate 64 may be positioned between the intake valve 52 and the intake manifold 44, such that the throttle body 62 is an intake duct throttle body.

[0014] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Universal exhaust oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, dual-state exhaust oxygen sensor may replace UEGO sensor 126.

[0015] In one example, converter 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each having multiple bricks, may be used. In one example, converter 70 may be a ternary catalyst.

[0016] Controller 12 in Figure 1 The controller 12 is shown as a conventional microcomputer, which includes: a microprocessor unit 102, an input / output port 104, a read-only memory 106 (e.g., non-transitory memory), a random access memory 108, a keep-alive memory 110, and a conventional data bus. The controller 12 is shown to receive various signals from sensors coupled to the engine 10 in addition to those previously discussed, including: engine coolant temperature (ECT) from a temperature sensor 112 coupled to a cooling sleeve 114; a position sensor 134 coupled to a driver demand pedal 130 to sense the distance of human displacement 132; a position sensor 154 coupled to a brake caliper pedal 150 to sense the distance of human displacement 132; a measurement of engine manifold pressure (MAP) from a pressure sensor 122 coupled to an intake manifold 44; an engine position sensor from a Hall effect sensor 118 sensing the position of the crankshaft 40; a measurement of the air mass entering the engine from a sensor 120; and a measurement of the throttle position from a sensor 58. Atmospheric pressure (sensor not shown) can also be sensed for processing by controller 12. In a preferred aspect of this specification, the engine position sensor 118 generates a predetermined number of equidistant pulses for each revolution of the crankshaft, thereby determining the engine speed (RPM).

[0017] In some examples, the engine may be coupled to an electric motor / battery system in a hybrid vehicle. Additionally, in some examples, other engine configurations may be employed, such as a diesel engine with multiple fuel injectors. Furthermore, the controller 12 may receive input and communicate conditions such as component degradation to the lights, or alternatively to the human / machine interface 171.

[0018] During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, generally, exhaust valve 54 is closed and intake valve 52 is open. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its maximum volume) is generally referred to by those skilled in the art as bottom dead center (BDC). During the compression stroke, both intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point where piston 36 is closest to the cylinder head at the end of its stroke (e.g., when combustion chamber 30 is at its minimum volume) is generally referred to by those skilled in the art as top dead center (TDC). In the process referred to below as injection, fuel is introduced into the combustion chamber. In the process referred to below as ignition, the injected fuel is ignited by a known ignition device such as spark plug 92, resulting in combustion. During the expansion stroke, the expanding gas pushes piston 36 back to the BDC. Crankshaft 40 converts the piston movement into rotational torque on the rotating shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture into exhaust manifold 48, and piston returns to the TDC. It should be noted that the above is merely illustrative, and the opening and / or closing timing of the intake and exhaust valves can vary, such as to provide positive or negative valve overlap, delayed intake valve closing, or various other examples.

[0019] Now for reference Figure 2 The diagram shows a plan view 200 of engine 10. Engine 10 is... Figure 1 The engine shown is the same engine, but in Figure 2 The image shows all the engine cylinders. In this example, the engine cylinders are numbered 1 through 8. Air is supplied to the cylinders via intake manifold 44. The first cylinder bank includes cylinders 1 through 4, and the second cylinder bank includes cylinders 5 through 8. Cylinders 1 through 4 are shown in fluid communication with exhaust manifold 48, and cylinders 5 through 8 are shown in fluid communication with exhaust manifold 220. Each of cylinders 1 through 8 includes a fuel injector, a spark plug, and intake / exhaust valves, as shown. Figure 1 As shown in the figure. It can also be understood that the methods described herein can be applied to V6, V10 and V12 engines.

[0020] A first oxygen sensor 126 is shown configured to sense exhaust gas from cylinders numbered 1 and 2. A second oxygen sensor 204 is shown configured to sense exhaust gas from cylinders 3 and 4. A third oxygen sensor 206 is shown configured to sense exhaust gas from cylinders numbered 5 and 7. A fourth oxygen sensor 208 is shown configured to sense exhaust gas from cylinders 6 and 8. Based on the exhaust gas flow from the cylinders as indicated by arrows 230 and 240, no cylinder is downstream of any of the exhaust gas sensors.

[0021] When the first oxygen sensor 126 is correctly wired to the controller 12, its output can be used as air-fuel ratio feedback or equivalence ratio feedback to control the fuel supplied to cylinders numbered 1 and 2. When the second oxygen sensor 204 is correctly wired to the controller 12, its output can be used as air-fuel ratio feedback or equivalence ratio feedback to control the fuel supplied to cylinders numbered 3 and 4. When the third oxygen sensor 206 is correctly wired to the controller 12, its output can be used as air-fuel ratio feedback or equivalence ratio feedback to control the fuel supplied to cylinders numbered 5 and 7. When the fourth oxygen sensor 208 is correctly wired to the controller 12, its output can be used as air-fuel ratio feedback or equivalence ratio feedback to control the fuel supplied to cylinders numbered 6 and 8. Therefore, for baseline engine and controller operation, the first oxygen sensor 126 is associated with cylinders numbered 1 and 2, the second oxygen sensor 204 with cylinders numbered 3 and 4, the third oxygen sensor 206 with cylinders numbered 5 and 7, and the fourth oxygen sensor 208 with cylinders numbered 6 and 8. However, because the oxygen sensors in individual cylinder banks are very close together, it is possible to miswire the oxygen sensors. For example, when the first oxygen sensor 126 is incorrectly wired (e.g., miswired) to the controller 12, its output can be used as air-fuel ratio feedback or equivalence ratio feedback to control the fuel supplied to cylinders numbered 3 and 4. Similarly, when the second oxygen sensor 204 is incorrectly wired to the controller 12, its output can be used as air-fuel ratio feedback or equivalence ratio feedback to control the fuel supplied to cylinders numbered 1 and 2.

[0022] Figure 1 and Figure 2The system provides a system comprising: an internal combustion engine including eight cylinders, at least eight fuel injectors, and four exhaust oxygen sensors; a first oxygen sensor located downstream of two cylinders in a first group; a second oxygen sensor located downstream of two cylinders in a second group; a third oxygen sensor located downstream of two cylinders in a third group; and a fourth oxygen sensor located downstream of two cylinders in a fourth group; and a controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to switch cylinders associated with the first group of cylinders and switch cylinders associated with the second group of cylinders in response to an indication of incorrect wiring of one of the first and second oxygen sensors. In a first example, the system further includes additional executable instructions stored in a non-transitory memory, the additional executable instructions causing the controller to switch cylinders associated with the third group of cylinders and switch cylinders associated with the fourth group of cylinders in response to an indication of incorrect wiring of one of the third and fourth oxygen sensors. In a second example that may include the first example, the system includes: wherein the indication of incorrect wiring is one or more control parameters diverging to a threshold. In a third example that may include one or both of the first and second examples, the system includes: wherein the indication of incorrect wiring is that the output of the second oxygen sensor is richer than the output of the first oxygen sensor when the first group of cylinders is commanded to be richer than the second group of cylinders. In a fourth example that may include one or more of the first to third examples, the system includes: wherein the indication of incorrect wiring is that the output of the first oxygen sensor is richer than the output of the second oxygen sensor when the second group of cylinders is commanded to be richer than the first group of cylinders. In a fifth example that may include one or more of the first to fourth examples, the system includes: wherein the controller includes additional executable instructions causing the controller to adjust a first air-fuel ratio or a first equivalence ratio of the two cylinders in the first group in response to the output of the first oxygen sensor, and additional executable instructions causing the controller to adjust a second air-fuel ratio or a second equivalence ratio in response to the output of the second oxygen sensor. In a sixth example, which may include one or more of the first to fifth examples, the system includes: wherein the controller includes additional executable instructions that cause the controller to adjust a third air-fuel ratio or a third equivalence ratio of two cylinders in a third group in response to the output of a third oxygen sensor, and additional executable instructions that cause the controller to adjust a fourth air-fuel ratio or a fourth equivalence ratio in response to the output of a fourth oxygen sensor.

[0023] Now back Figure 3This illustrates an example diagnostic sequence for determining whether the oxygen sensors in the cylinder bank are incorrectly wired (e.g., one oxygen sensor is wired to a wire used for a second oxygen sensor) when a first fuel control strategy is applied to the engine. This can be achieved via... Figure 1 and Figure 2 The system and Figure 6 Methods of collaboration to provide Figure 3 sequence. Figure 3 The graph is time-aligned, and the vertical lines represent the relevant time for the sequence of operations.

[0024] The first fuel control strategy receives the outputs of oxygen sensors associated with two cylinders in the cylinder bank and generates fuel quality feedback corrections for the two cylinders associated with the oxygen sensors based on the oxygen sensor outputs. For example, oxygen sensor 126 outputs a signal, and the fuel quality is adjusted according to the output of oxygen sensor 126. Figure 2 The diagram shows the fuel quantity for cylinders 1 and 2 of the engine. Similarly, a first fuel control strategy receives the output of oxygen sensor 204 associated with cylinders 3 and 4, and generates fuel quality feedback corrections for cylinders 3 and 4 based on the output of oxygen sensor 204. Likewise, the fuel delivered to cylinders 5 and 7 can be adjusted in response to the output of oxygen sensor 206, and the fuel delivered to cylinders 6 and 8 can be adjusted in response to the output of oxygen sensor 208. The fuel quality feedback corrections can be calculated independently for each pair of cylinders based on the output of the oxygen sensor associated with a specific pair of engine cylinders. Therefore, the four feedback controllers of the eight-cylinder engine can be referred to as separate fuel controllers.

[0025] from Figure 3 The first curve, starting at the top, represents the relationship between the fuel control signal and time. The vertical axis indicates the state of fuel control, and when trace 302 is at a higher level near the arrow on the vertical axis, fuel control is in open-loop mode (e.g., adjusting the fuel quantity in response to the amount of air entering the engine rather than in response to the output of the oxygen sensor). When trace 302 is at a lower level near the horizontal axis, fuel control is in closed-loop mode. Trace 302 represents the fuel control state. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0026] from Figure 3The second curve, starting at the top, represents the relationship between the fuel mass feedback correction (multiplier) value of the cylinder group in the cylinder bank and time. The vertical axis indicates the fuel mass feedback correction value, and the fuel mass feedback correction value increases in the direction of the arrow on the vertical axis. Solid trace 304 represents the fuel mass feedback correction for two cylinders (e.g., the first group of cylinders) in a cylinder bank (e.g., adjacent cylinders that share the same cylinder head). Dashed trace 306 represents the fuel mass feedback correction for two other cylinders (e.g., the second group of cylinders). Horizontal line 350 represents the lower threshold of the fuel mass feedback correction (multiplier), and horizontal line 352 represents the upper threshold of the fuel mass feedback correction (multiplier). The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0027] from Figure 3 The third curve, starting at the top, represents the relationship between the measured equivalence ratio (e.g., λ, where λ = cylinder air-fuel ratio / cylinder stoichiometric air-fuel ratio) and time. The vertical axis indicates the measured or observed equivalence ratio as observed by the oxygen sensor, and the equivalence ratio increases in the direction of the arrow on the vertical axis (e.g., becomes leaner). The dashed trace 308 corresponds to the equivalence ratio measured for the second group of cylinders, and the solid trace 310 corresponds to the equivalence ratio observed for the first group of cylinders. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0028] At time t0, fuel is supplied to the engine in open-loop mode. The fuel mass feedback correction multiplier for the first and second cylinder groups is 1 (i.e., no feedback or closed-loop adjustment is applied). The measured equivalence ratio of the first and second cylinder groups is close to 1.

[0029] At time t1, the fuel control state switches from open-loop to closed-loop. After a cold start of the engine, the fuel control state can switch from open-loop to closed-loop. Shortly after time t1, in response to the outputs of the first and second oxygen sensors applied by the fuel controller, the fuel mass feedback correction for the first group of cylinders (e.g., trace 304) begins to diverge towards a horizontal line 350 (e.g., the lower limit threshold of the fuel mass feedback correction), and the fuel mass feedback correction for the second group of cylinders (e.g., trace 306) begins to diverge towards a horizontal line 352 (e.g., the upper limit threshold of the fuel mass feedback correction), striving to achieve λ = 1 for each of the first and second cylinder groups. This divergence is due to closed-loop control instability caused by a miswired oxygen sensor. Shortly after time t1, the measured equivalence ratio for the first group of cylinders indicates a rich feed, and the measured equivalence ratio for the second group of cylinders indicates a lean feed. The fuel mass feedback correction value and the measured equivalence ratio between time t1 and time t2 indicate the signal when the controller wiring for the first oxygen sensor is connected to the second oxygen sensor, and vice versa. Specifically, trace 306 exceeds threshold 350 and trace 304 is less than threshold 352, thus confirming that the engine's closed-loop fuel control is unstable and that the cylinder group's equivalence ratio cannot reach a value of 1 due to incorrect wiring of the oxygen sensor. Furthermore, the indications of the lean and rich equivalence ratios of the two cylinder groups support this conclusion.

[0030] At time t2, the fuel controller exits closed-loop mode and re-enters open-loop operation. The fuel quality feedback correction (multiplier) value is restored to 1, and the measured equivalence ratio shifts toward value 1.

[0031] Therefore, fuel quality feedback correction values ​​can be applied to determine whether the wires of the first sensor are connected to the second sensor and whether the wires of the second sensor are connected to the first sensor. If an incorrect wiring is identified, the controller can internally compensate for the incorrectly wired sensor and correct the engine cylinder group equivalence ratio.

[0032] Now for reference Figure 4 This illustrates an example diagnostic sequence for determining whether the oxygen sensors in the cylinder bank are incorrectly wired (e.g., one oxygen sensor is wired to the same wire used for the second oxygen sensor) when a second fuel control strategy is applied to the engine. This can be achieved via... Figure 1 and Figure 2 The system and Figure 6 Methods of collaboration to provide Figure 4 sequence. Figure 4 The graph is time-aligned, and the vertical lines represent the relevant time for the sequence of operations.

[0033] The second fuel control strategy averages the outputs from the two oxygen sensors in the cylinder bank and performs fuel quality feedback correction on the fuel supplied to the cylinders in the cylinder bank based on the average output of the two oxygen sensors. For example, Figure 2 The output signals of oxygen sensors 126 and 204 are summed and divided by two to generate the average output of oxygen sensors 126 and 204. The oxygen sensor output is then adjusted based on the average output delivered to… Figure 2 The diagram shows the fuel quantity for cylinders 1 through 4 of the engine. Similarly, the second fuel control strategy receives the outputs from oxygen sensors 206 and 208, averages the outputs, and generates a second fuel quality feedback correction from the averaged output. The fuel injected into cylinders 5 through 8 is adjusted based on the second fuel quality correction.

[0034] from Figure 4 The first curve, starting at the top, represents the relationship between the commanded fuel mass multiplier and time. The vertical axis indicates the value of the commanded fuel mass multiplier, and the commanded fuel mass multiplier increases in the direction of the arrow on the vertical axis. As the commanded fuel mass multiplier increases, it makes the air-fuel ratio of the cylinder richer. Trace 402 represents the commanded fuel mass multiplier for cylinders 1 and 2 of cylinder bank 3. Trace 404 represents the commanded fuel mass multiplier for cylinders 3 and 4 of cylinder bank 3. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0035] from Figure 4 The second curve, starting at the top, represents the relationship between the measured equivalence ratio (e.g., λ, where λ = cylinder air-fuel ratio / cylinder stoichiometric air-fuel ratio) and time. The vertical axis indicates the measured or observed equivalence ratio as observed by the oxygen sensor, and the equivalence ratio increases in the direction of the arrow on the vertical axis (e.g., becomes leaner). The dashed trace 406 represents the equivalence ratio measured by oxygen sensor 126 for cylinders 1 and 2. The solid trace 408 represents the equivalence ratio measured by oxygen sensor 204 for cylinders 3 and 4. The horizontal axis represents time, and time increases from the left to the right of the graph.

[0036] At time t10, fuel is supplied to the engine in closed-loop mode. The commanded fuel mass multiplier is corrected based on fuel mass feedback. The commanded fuel mass multipliers for cylinders 1 through 4 are close to 1. The measured equivalence ratios for cylinders numbered 1 through 4 are close to 1.

[0037] At time t11, when the commanded fuel mass multiplier changes to zero (closed-loop mode is disabled), the engine enters fuel cutoff, where fuel injection to cylinders numbered 1 through 4 stops. Because no fuel is injected and air flows through cylinders 1 through 4, the measured equivalence ratios of cylinders 1 through 4 increase and exceed the proportional limit.

[0038] At time t12, the engine returns from fuel cut-off mode and re-engages closed-loop mode. Following fuel cut-off mode, the cylinder bank operates on average with a rich air-fuel mixture to restart the catalytic converter. By operating the rich mixture in two of the four cylinders in the cylinder bank, the swapped UEGO sensor wiring can be detected simultaneously with catalytic converter restart. The commanded fuel mass multiplier for cylinders 1 and 2 remains above a value of 1 to determine whether cylinders 1 and 2 will indicate a rich mixture if oxygen sensor 126 is correctly wired. The commanded fuel mass multiplier for cylinders 3 and 4 remains at a value of 1 to determine whether cylinders 3 and 4 will indicate a near-stoichiometric mixture if oxygen sensor 204 is correctly wired. However, in this example, the measured equivalence ratio (dashed line 406) for cylinders 1 and 2 indicates a stoichiometric mixture. The measured equivalence ratio (solid line 408) for cylinders 3 and 4 indicates a richer mixture (e.g., λ < 1).

[0039] Therefore, in this example, although cylinders numbered 1 and 2 are supplied with a rich air-fuel mixture, the stoichiometric ratio is indicated by an oxygen sensor that should sense the output of cylinders numbered 1 and 2. Similarly, although cylinders numbered 3 and 4 are supplied with a stoichiometric air-fuel mixture, the oxygen sensor that should sense the output of cylinders numbered 3 and 4 indicates the rich equivalence ratio. Therefore, it can be determined that the wire for oxygen sensor 126 is connected to oxygen sensor 204, and vice versa.

[0040] Now for reference Figure 5 This illustrates another example diagnostic sequence for determining whether the oxygen sensors in the cylinder bank are incorrectly wired (e.g., one oxygen sensor is wired to the same wire used for the second oxygen sensor) when a third fuel control strategy is applied to the engine. This can be achieved via... Figure 1 and Figure 2 The system and Figure 6 Methods of collaboration to provide Figure 5 sequence. Figure 5 The graph is time-aligned, and the vertical lines represent the relevant time for the sequence of operations.

[0041] The third fuel control strategy averages the outputs from the two oxygen sensors in the cylinder bank and performs an average-based fuel quality feedback correction on the fuel supplied to the cylinders in the cylinder bank based on the average output of the two oxygen sensors. Additionally, the third fuel control strategy also uses the difference between the outputs of the two oxygen sensors in the first cylinder bank and performs an additional difference-based fuel quality feedback correction on the fuel supplied to the cylinders in the first cylinder bank based on the difference between the outputs of the two oxygen sensors. The fuel injected into cylinders 1 to 4 is adjusted based on the average-based fuel quality feedback correction and the difference-based fuel quality feedback correction. Similarly, the third fuel control strategy receives the outputs of oxygen sensors 206 and 208, averages the outputs, and generates an average-based fuel quality feedback correction from the average output of the second cylinder bank. Furthermore, the third fuel control strategy generates a difference between the outputs of oxygen sensors 206 and 208 and generates an additional difference-based fuel quality feedback correction for the cylinders in the second cylinder bank based on the difference. The fuel injected into cylinders 5 to 8 is adjusted based on the average-based fuel quality feedback correction and the difference-based fuel quality feedback correction.

[0042] from Figure 5 The first curve, starting at the top, represents the relationship between the measured average equivalent ratio of the engine cylinders and time (e.g., the average output of oxygen sensors 126 and 204). The vertical axis indicates the measured average equivalent ratio, and the value of the measured average equivalent ratio increases in the direction of the arrow on the vertical axis. Trace 502 represents the measured average equivalent ratio of the engine cylinders (e.g., cylinders 1 to 4). The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0043] from Figure 5 The second curve, starting from the top, represents the relationship between the activation state of the difference-based fuel controller and time. The vertical axis represents the state of the difference-based fuel controller, and the difference-based fuel controller is activated or started when trace 504 is at a higher level near the arrow on the vertical axis. The difference-based fuel controller is not activated when trace 504 is at a lower level near the horizontal axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0044] from Figure 5 The third curve from the top represents the average-based fuel quality feedback correction multiplier (e.g., the average of the outputs of oxygen sensors 126 and 204 is used to generate an average-based fuel feedback correction applied to the fuel supplied to cylinders 1 through 4). The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0045] from Figure 5The fourth curve, starting at the top, is a graph of the differential-based fuel controller output versus time (e.g., the fuel quality feedback correction multiplier based on the difference in outputs from oxygen sensors 126 and 204). Solid trace 508 represents the output of the differential-based fuel controller applied to cylinders 1 and 2, and dashed trace 510 represents the output of the differential-based fuel controller applied to cylinders 3 and 4. The average of traces 508 and 510 is equal to 1. Horizontal line 550 represents the upper threshold of the differential-based fuel controller output, and horizontal line 552 represents the lower threshold of the differential-based fuel controller output. The horizontal axis represents time, and time increases from the left to the right of the graph.

[0046] At time t20, fuel is supplied to the engine in closed-loop mode, where the difference-based fuel controller is disabled and only the average-based fuel controller is enabled. The measured equivalence ratio is close to a value of 1. The average-based fuel mass feedback correction (multiplier) oscillates around a value of 1, and the difference-based fuel controller output is equal to 1.

[0047] At time t21, the differential fuel controller is activated, which causes the output of the differential-based fuel controller to diverge while maintaining an average output of 1. The measured average equivalence ratio remains approximately 1 and the fuel mass feedback correction (multiplier) based on the average remains close to 1.

[0048] Between time t21 and time t22, the difference-based fuel controller remains active, and its output exceeds threshold 550 and drops below threshold 552. This may indicate incorrect oxygen sensor wiring. The measured average equivalence ratio remains approximately 1, and the average-based fuel mass feedback correction (multiplier) remains close to 1.

[0049] At time t22, the difference-based fuel controller is deactivated, causing its output to return to value 1. The measured average equivalence ratio remains close to value 1, and the average-based fuel mass feedback correction (multiplier) remains close to value 1.

[0050] Therefore, the output of the fuel controller based on the difference exceeding or falling below a predetermined threshold can indicate the wiring of the pair of oxygen sensors in the cylinder bank. Conversely, if the output of the fuel controller based on the difference does not exceed threshold 550 and falls below threshold 552, it can be determined that the oxygen sensors in the cylinder bank are not incorrectly wired.

[0051] Now for reference Figure 6 This paper describes a method for using an oxygen sensor to operate an engine and detect incorrect wiring in the cylinder bank. Figure 6 The method can be incorporated as executable instructions stored in non-transitory memory. Figure 1 In the system.Figure 6 The method can lead to Figure 1 The controller receives input from one or more sensors described herein and adjusts the position or operating state of one or more actuators described herein in the physical world. Method 600 is described with respect to a single cylinder bank, but method 600 can be applied to two cylinder banks of an engine. Method 600 can be executed while the engine is operating and the output of each oxygen sensor of the engine is monitored via the controller.

[0052] At point 602, method 600 determines whether the first or third fuel control strategy has been activated. If yes, the answer is yes, and method 600 proceeds to 620. Otherwise, the answer is no, and method 600 proceeds to 604. If the answer is no, the second fuel control strategy is activated.

[0053] At 604, method 600 performs open-loop or closed-loop control on the fuel delivered to the cylinders in the cylinder bank. During open-loop control, method 600 adjusts the amount of fuel injected into the cylinders in the cylinder bank based on the amount of air entering the cylinders in the cylinder bank. During open-loop control, the output of the oxygen sensor is not used to change the fuel injection amount. On the other hand, if closed-loop fuel control is initiated, the output of the oxygen sensor is used via the fuel controller to adjust the fuel injected into the cylinders in the cylinder bank. The cylinder bank includes, for example, […]. Figure 2 In one example of the two oxygen sensors shown, the fuel controller determines the average equivalence ratio based on the outputs of the two oxygen sensors in the cylinder bank, and adjusts the fuel supply to the cylinders in the cylinder bank based on the average equivalence ratio.

[0054] Method 600 operates the engine based on a fuel controller that averages the outputs of two oxygen sensors in the cylinder bank and adjusts the fuel supplied to the engine cylinders according to the average λ value of the cylinder bank. Method 600 proceeds to 606.

[0055] At 606, method 600 perturbs a group of cylinders in the cylinder bank by adjusting for rich or lean fuel. Alternatively, method 600 can perturb a group of cylinders in the cylinder bank with opposite fuel adjustments. For example, a first group of cylinders in the cylinder bank can be perturbed with a lean air-fuel mixture, and a second group of cylinders in the cylinder bank can be perturbed with a rich air-fuel mixture. As another alternative, method 600 can adjust the equivalence ratio of a group of cylinders in the cylinder bank while keeping the equivalence ratio of the second group of cylinders in the cylinder bank stable. Method 600 proceeds to 608.

[0056] At 608, method 600 determines whether there is an unexpected change in the λ value measured by one or more oxygen sensors. In one example, method 600 may determine whether the λ value of the gas generated by a first group of cylinders in a cylinder bank that is commanded to reach a predetermined λ value (e.g., 1) is more lean than a first threshold or more rich than a second threshold. A second group of cylinders in the cylinder bank may be commanded to operate with a λ value that is more lean or more rich than stoichiometric. Figure 4 An example of this operation is shown in the figure.

[0057] In another example, method 600 can determine whether the λ value of the gas generated by the first group of cylinders ordered to reach a predetermined λ value (e.g., 1) is less than a first threshold when the first group of cylinders is ordered to operate with a rich air-fuel mixture and the second group of cylinders is ordered to operate with a lean air-fuel mixture.

[0058] In another example, method 600 may determine whether the value of the gas generated by the first group of cylinders in the cylinder bank, which is ordered to oscillate around a predetermined value (e.g., 1), does not change as expected when the second group of cylinders in the cylinder bank is commanded to operate with a constant λ air-fuel mixture.

[0059] If an unexpected λ value is determined during one of the air-fuel ratio control procedures mentioned above, the answer is yes and method 600 proceeds to 610. Otherwise, the answer is no and method 600 proceeds to 612.

[0060] At 610, method 600 changes or switches the mapping of the cylinder to one or more oxygen sensors. For example, if the controller has internally assigned a first controller input to... Figure 2 If the second input is assigned to sensor 126 and the first input is assigned to sensor 204, then method 600 can reassign the second controller input to sensor 126 and the first controller input to sensor 204, such that feedback is received from oxygen sensors associated with a particular set of cylinders in the fuel control strategy.

[0061] Alternatively, method 600 may reassign or switch cylinders associated with a particular oxygen sensor. For example, if an unexpected λ value is observed via one or more oxygen sensors, the cylinder associated with the oxygen sensor in which the unexpected λ value is observed within the controller is reassigned to a second oxygen sensor, and the cylinder associated with the second oxygen sensor in the controller may be reassigned to a cylinder previously assigned to an oxygen sensor in which the unexpected λ value was observed. Reassigning or switching cylinders associated with oxygen sensors in the controller causes the controller to change the way the oxygen sensors are applied in feedback control to change the fuel injected into the cylinders. Thus, switching the cylinder associated with the oxygen sensor from the first group of cylinders to the second group of cylinders may cause the air-fuel ratio of the first group of cylinders to no longer be affected by the output of the oxygen sensor, and may also cause the air-fuel ratio of the second group of cylinders to no longer be affected by the output of the oxygen sensor. Method 600 proceeds to 612.

[0062] At point 612, method 600 resumes basic fuel control and proceeds to exit. Basic fuel control can be either open-loop or closed-loop fuel control. Method 600 proceeds to exit.

[0063] At point 620, method 600 performs open-loop fuel control and changes to closed-loop fuel control, such as Figure 3 As shown in the diagram. Method 600 can change from open-loop operation to closed-loop operation after a cold engine start or after a fuel cut-off mode when fuel injection to previously deactivated cylinders is resumed. Method 600 can operate the engine by controlling the fuel supply to two cylinders in the cylinder bank based on the output of a first oxygen sensor, and method 600 can control the fuel supply to the other two cylinders in the cylinder bank based on the output of a second oxygen sensor. Alternatively, method 600 can adjust the fuel supply to four cylinders in the cylinder bank based on the average of the outputs of the two oxygen sensors associated with the cylinder bank and the difference between the outputs of the two oxygen sensors associated with the cylinder bank. Method 600 proceeds to 622.

[0064] At 622, method 600 performs an oxygen sensor verification sequence. This verification sequence allows method 600 to determine if the fuel controller output is diverging to indicate an incorrectly wired oxygen sensor (e.g., a connector connected to an unintended oxygen sensor). In one example, if the first group of cylinders in the cylinder bank is commanded to a lean threshold that should not be exceeded, while the second group of cylinders in the cylinder bank is commanded to a rich threshold that should not be exceeded once closed-loop operation is initiated, method 600 can determine that the fuel controller is diverging. The divergence from near the stoichiometric threshold to either the lean or rich threshold can depend on the initial conditions.

[0065] In some examples, an acknowledgment sequence can be performed if the oxygen sensor output causes the cylinder's fuel controller to diverge to the opposite threshold. The acknowledgment sequence may include perturbing a pair of cylinders with a fuel mixture (e.g., rich or lean) and determining whether a corresponding λ value is observed from an oxygen sensor not associated with a cylinder that has been commanded to be perturbed rich or lean. In an alternative acknowledgment sequence, the first group of cylinders in the cylinder bank can be perturbed with a lean air-fuel mixture, while the second group can be perturbed with a rich air-fuel mixture. If the oxygen sensor associated with the first group of cylinders indicates rich and the oxygen sensor associated with the second group indicates lean, the wiring of the two oxygen sensors can be determined to be reversed. In yet another alternative acknowledgment sequence, the first group of cylinders in the cylinder bank can be perturbed: the first cylinder of the group is rich; the second cylinder of the group is lean. If the oxygen sensor associated with the first group of cylinders does not indicate alternating rich and lean λ values, the wiring of the two oxygen sensors can be determined to be reversed.

[0066] At 624, method 600 determines whether the fuel controller output diverges to indicate an incorrectly wired oxygen sensor (e.g., a connector connected to an unintended oxygen sensor). If so, the answer is yes, and method 600 proceeds to 626. Otherwise, the answer is no, and method 600 proceeds to 628.

[0067] At 626, method 600 changes the mapping of the cylinder to one or more oxygen sensors. For example, if the controller has internally assigned a first controller input to... Figure 2 If the second input is assigned to sensor 126 and the first input is assigned to sensor 204, then method 600 can reassign the second controller input to sensor 126 and the first controller input to sensor 204, such that feedback is received from oxygen sensors associated with a particular set of cylinders in the fuel control strategy.

[0068] Alternatively, method 600 may reassign cylinders associated with a particular oxygen sensor. For example, if an unexpected λ value is observed via one or more oxygen sensors, the cylinder associated with the oxygen sensor where the unexpected λ value was observed is reassigned to a second oxygen sensor, and the cylinder associated with the second oxygen sensor may be reassigned to the cylinder previously assigned to the oxygen sensor where the unexpected λ value was observed. Method 600 proceeds to 628.

[0069] At point 628, method 600 resumes basic fuel control and proceeds to exit. Basic fuel control can be either open-loop or closed-loop fuel control. Method 600 proceeds to exit.

[0070] In this way, if the output of one or more oxygen sensors is unexpected for a particular cylinder (e.g., when its associated cylinder has become rich or lean before it has been commanded to be rich or lean by injecting more or less fuel into the cylinder), the controller can internally change which engine cylinders are associated with a particular oxygen sensor.

[0071] therefore, Figure 6 A method provides a way of operating an engine, the method comprising: monitoring exhaust gas from a first group of cylinders in a cylinder bank of the engine via a first oxygen sensor; monitoring exhaust gas from a second group of cylinders in the cylinder bank via a second oxygen sensor; and switching a cylinder associated with the first group of cylinders and switching a cylinder associated with the second group of cylinders in response to an indication of incorrect wiring of one of the first and second oxygen sensors. In a first example, the method comprises: wherein switching a cylinder associated with the first group of cylinders and switching a cylinder associated with the second group of cylinders comprises switching a cylinder associated with the first group of cylinders to a cylinder associated with the second group of cylinders and switching a cylinder associated with the second group of cylinders to a cylinder associated with the first group of cylinders. In a second example that may include the first example, the method comprises: wherein switching a cylinder associated with the first group of cylinders and switching a cylinder associated with the second group of cylinders causes fuel adjustment of the first group of cylinders in response to an output of a second oxygen sensor, and causes fuel adjustment of the second group of cylinders in response to an output of a first oxygen sensor. In a third example that may include one or both of the first and second examples, the method includes: wherein the indication of incorrect wiring is that a fuel control parameter diverges to a threshold range. In a fourth example that may include one or more of the first to third examples, the method includes: wherein the fuel control parameter diverges to a threshold range during closed-loop fuel control. In a fifth example that may include one or more of the first to fourth examples, the method includes: wherein the indication of incorrect wiring is based on commanding enrichment of a first group of cylinders and detecting enrichment of a second group of cylinders. In a sixth example that may include one or more of the first to fifth examples, the method includes: wherein the indication of incorrect wiring is based on commanding enrichment of a second group of cylinders and detecting enrichment of a first group of cylinders. In a seventh example, which may include one or more of the first to sixth examples, the method further includes: monitoring exhaust gas from a second group of cylinders in a second cylinder bank via a third oxygen sensor; monitoring exhaust gas from a fourth group of cylinders in the cylinder bank via a fourth oxygen sensor; and switching a cylinder associated with the third group of cylinders and a cylinder associated with the fourth group of cylinders in response to an indication of incorrect wiring of one of the third and fourth oxygen sensors.

[0072] Figure 6The method also provides a method for operating an engine, the method comprising: operating the engine in a fuel cut-off mode; in response to exiting the fuel cut-off mode, commanding a first group of cylinders in the engine's cylinder bank to a first equivalence ratio and commanding a second group of cylinders in the cylinder bank to a second equivalence ratio; and switching cylinders associated with the first group of cylinders to cylinders associated with the second group of cylinders in response to a first oxygen sensor instructing the first group of cylinders to operate at the second equivalence ratio. In a first example, the method further comprises switching cylinders associated with the second group of cylinders to cylinders associated with the first group of cylinders in response to a second oxygen sensor instructing the second group of cylinders to operate at the first equivalence ratio. In a second example that may include the first example, the method further comprises: after switching cylinders associated with the first group of cylinders to cylinders associated with the second group of cylinders, operating the second group of cylinders in response to the output of the first oxygen sensor. In a third example that may include one or both of the first and second examples, the method comprises: wherein operating the second group of cylinders includes adjusting the equivalence ratio of the second group of cylinders. In a fourth example, which may include one or more of the first to third examples, the method includes: wherein the first equivalent ratio is different from the second equivalent ratio.

[0073] It should be noted 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 implemented by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Thus, the various actions, operations, and / or functions shown may be executed in the order shown, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily necessary to achieve the features and advantages of the exemplary examples described herein, but is provided for ease of illustration and description. One or more of the shown actions, operations, and / or functions can be repeatedly executed according to the specific strategy used. Furthermore, the actions, operations, and / or functions can be graphically represented by code programmed into a non-transitory memory of a computer-readable storage medium in an engine control system, wherein the described actions are implemented by executing instructions in conjunction with an electronic controller in a system including various engine hardware components.

[0074] This specification concludes here. Many variations and modifications will arise in those skilled in the art upon reading this specification without departing from its spirit and scope. For example, this specification may be beneficial to I3, I4, I5, V6, V8, V10, and V12 engines operating with natural gas, gasoline, diesel, or alternative fuels.

[0075] According to the present invention, a method for operating an engine includes: monitoring exhaust gas from a first group of cylinders in a cylinder bank of the engine via a first oxygen sensor; monitoring exhaust gas from a second group of cylinders in the cylinder bank via a second oxygen sensor; and switching a cylinder associated with the first group of cylinders and switching a cylinder associated with the second group of cylinders in response to an indication of incorrect wiring of one of the first oxygen sensor and the second oxygen sensor.

[0076] In one aspect of the invention, switching a cylinder associated with the first group of cylinders and switching a cylinder associated with the second group of cylinders includes switching a cylinder associated with the first group of cylinders to the second group of cylinders and switching a cylinder associated with the second group of cylinders to the first group of cylinders.

[0077] In one aspect of the invention, switching the cylinder associated with the first group of cylinders and switching the cylinder associated with the second group of cylinders causes fuel adjustment of the first group of cylinders in response to the output of the second oxygen sensor, and causes fuel adjustment of the second group of cylinders in response to the output of the first oxygen sensor.

[0078] In one aspect of the invention, the indication of the faulty wiring is that the fuel control parameters diverge into a threshold range.

[0079] In one aspect of the invention, the fuel control parameters diverge to the threshold range during closed-loop fuel control.

[0080] In one aspect of the invention, the indication of the faulty wiring is based on commanding the enrichment of the first group of cylinders and detecting the enrichment of the second group of cylinders.

[0081] In one aspect of the invention, the indication of the faulty wiring is based on commanding the enrichment of the second group of cylinders and detecting the enrichment of the first group of cylinders.

[0082] In one aspect of the invention, the method includes: monitoring exhaust gas from a third group of cylinders in a second cylinder bank via a third oxygen sensor; monitoring exhaust gas from a fourth group of cylinders in the cylinder bank via a fourth oxygen sensor; and switching a cylinder associated with the third group of cylinders and a cylinder associated with the fourth group of cylinders in response to an indication of incorrect wiring of one of the third and fourth oxygen sensors.

[0083] According to the present invention, a system is provided comprising: an internal combustion engine including eight cylinders, at least eight fuel injectors and four exhaust oxygen sensors, a first oxygen sensor located downstream of two cylinders in a first group, a second oxygen sensor located downstream of two cylinders in a second group, a third oxygen sensor located downstream of two cylinders in a third group, and a fourth oxygen sensor located downstream of two cylinders in a fourth group; and a controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to switch cylinders associated with the first group of cylinders and switch cylinders associated with the second group of cylinders in response to an indication of incorrect wiring of one of the first oxygen sensor and the second oxygen sensor.

[0084] According to an embodiment, the invention is further characterized by additional executable instructions stored in a non-transitory memory, which cause the controller to switch the cylinder associated with the third group of cylinders and switch the cylinder associated with the fourth group of cylinders in response to an indication of incorrect wiring of one of the third oxygen sensor and the fourth oxygen sensor.

[0085] According to an embodiment, the indication of the faulty wiring is that one or more control parameters diverge to a threshold.

[0086] According to an embodiment, the indication of incorrect wiring is that when the first group of cylinders is commanded to have a richer oxygen supply than the second group of cylinders, the output of the second oxygen sensor indicates a richer oxygen supply than the output of the first oxygen sensor.

[0087] According to an embodiment, the indication of incorrect wiring is that when the second group of cylinders is commanded to have a richer oxygen supply than the first group of cylinders, the output of the first oxygen sensor indicates a richer oxygen supply than the output of the second oxygen sensor.

[0088] According to an embodiment, the controller includes additional executable instructions that cause the controller to adjust a first air-fuel ratio or a first equivalence ratio of the two cylinders in the first group in response to the output of the first oxygen sensor, and additional executable instructions that cause the controller to adjust a second air-fuel ratio or a second equivalence ratio in response to the output of the second oxygen sensor.

[0089] According to an embodiment, the controller includes additional executable instructions that cause the controller to adjust a third air-fuel ratio or a third equivalence ratio of the two cylinders in the third group in response to the output of the third oxygen sensor, and additional executable instructions that cause the controller to adjust a fourth air-fuel ratio or a fourth equivalence ratio in response to the output of the fourth oxygen sensor.

[0090] According to the present invention, a method for operating an engine includes: operating the engine in a fuel cut-off mode; in response to exiting the fuel cut-off mode, commanding a first group of cylinders in the cylinder bank of the engine to a first equivalence ratio and commanding a second group of cylinders in the cylinder bank to a second equivalence ratio; and switching the cylinders associated with the first group of cylinders to the cylinders associated with the second group of cylinders in response to a first oxygen sensor instructing the first group of cylinders to operate at the second equivalence ratio.

[0091] In one aspect of the invention, the method includes switching a cylinder associated with the second group of cylinders to a cylinder associated with the first group of cylinders in response to a second oxygen sensor instructing the second group of cylinders to operate at the first equivalence ratio.

[0092] In one aspect of the invention, the method includes, after switching a cylinder associated with the first group of cylinders to a cylinder associated with the second group of cylinders, operating the second group of cylinders in response to the output of the first oxygen sensor.

[0093] In one aspect of the invention, operating the second group of cylinders includes adjusting the equivalence ratio of the second group of cylinders.

[0094] In one aspect of the invention, the first equivalence ratio is different from the second equivalence ratio.

Claims

1. A method for operating an engine, comprising: The exhaust gas of the first group of cylinders in the cylinder bank of the engine is monitored via a first oxygen sensor; The exhaust gas from the second group of cylinders in the cylinder bank is monitored via a second oxygen sensor; as well as In response to an indication of incorrect wiring of either the first oxygen sensor or the second oxygen sensor, the cylinder associated with the first group of cylinders is switched and the cylinder associated with the second group of cylinders is switched.

2. The method of claim 1, wherein switching the cylinder associated with the first group of cylinders and switching the cylinder associated with the second group of cylinders includes switching the cylinder associated with the first group of cylinders to the second group of cylinders and switching the cylinder associated with the second group of cylinders to the first group of cylinders.

3. The method of claim 1, wherein switching the cylinders associated with the first group of cylinders and switching the cylinders associated with the second group of cylinders causes fuel adjustment of the first group of cylinders in response to the output of the second oxygen sensor, and causes fuel adjustment of the second group of cylinders in response to the output of the first oxygen sensor.

4. The method of claim 1, wherein the indication of the faulty wiring is that the fuel control parameters diverge into a threshold range.

5. The method of claim 4, wherein the fuel control parameters diverge to the threshold range during closed-loop fuel control.

6. The method of claim 1, wherein the indication of the faulty wiring is based on commanding the enrichment of the first group of cylinders and detecting the enrichment of the second group of cylinders.

7. The method of claim 1, wherein the indication of the faulty wiring is based on commanding the enrichment of the second group of cylinders and detecting the enrichment of the first group of cylinders.

8. The method of claim 1, further comprising: The exhaust gas from the third group of cylinders in the second cylinder bank is monitored via a third oxygen sensor; The exhaust gas from the fourth cylinder in the cylinder bank is monitored via a fourth oxygen sensor; as well as In response to an indication of incorrect wiring of one of the third and fourth oxygen sensors, the cylinder associated with the third group of cylinders is switched and the cylinder associated with the fourth group of cylinders is switched.

9. A system comprising: An internal combustion engine, the internal combustion engine comprising eight cylinders, at least eight fuel injectors, and four exhaust oxygen sensors, a first oxygen sensor located downstream of two cylinders in a first group, a second oxygen sensor located downstream of two cylinders in a second group, a third oxygen sensor located downstream of two cylinders in a third group, and a fourth oxygen sensor located downstream of two cylinders in a fourth group; and The controller includes executable instructions stored in a non-transitory memory, the executable instructions causing the controller to switch cylinders associated with the first group of cylinders and switch cylinders associated with the second group of cylinders in response to an indication of incorrect wiring of one of the first oxygen sensor and the second oxygen sensor.

10. The system of claim 9, further comprising additional executable instructions stored in a non-transitory memory, the additional executable instructions causing the controller to switch cylinders associated with the third group of cylinders and switch cylinders associated with the fourth group of cylinders in response to an indication of incorrect wiring of one of the third oxygen sensor and the fourth oxygen sensor.

11. The system of claim 9, wherein the indication of the faulty wiring is one or more control parameters diverging to a threshold.

12. The system of claim 9, wherein the indication of incorrect wiring is that when the first group of cylinders is commanded to have a richer oxygen supply than the second group of cylinders, the output of the second oxygen sensor indicates a richer oxygen supply than the output of the first oxygen sensor.

13. The system of claim 9, wherein the indication of incorrect wiring is that when the second group of cylinders is commanded to have a richer oxygen supply than the first group of cylinders, the output of the first oxygen sensor indicates a richer oxygen supply than the output of the second oxygen sensor.

14. The system of claim 9, wherein the controller includes additional executable instructions causing the controller to adjust a first air-fuel ratio or a first equivalence ratio of the first two cylinders in response to the output of the first oxygen sensor, and additional executable instructions causing the controller to adjust a second air-fuel ratio or a second equivalence ratio in response to the output of the second oxygen sensor.

15. The system of claim 14, wherein the controller includes additional executable instructions causing the controller to adjust a third air-fuel ratio or a third equivalence ratio of the two cylinders in the third group in response to the output of the third oxygen sensor, and additional executable instructions causing the controller to adjust a fourth air-fuel ratio or a fourth equivalence ratio in response to the output of the fourth oxygen sensor.

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