Abstract: A system according to the principles of the present disclosure includes a fault command module, a fuel control module, and a fault detection module. The fault command module selectively generates a command to induce a fuel system fault based on a user input. The fuel control module automatically adjusts a fuel correction factor to a target value outside of a first predetermined range in response to the command to induce a fuel system fault. The fuel control module actuates a fuel injector associated with a cylinder of an engine based on the fuel correction factor. The fault detection module detects a fuel system fault when the fuel correction factor is outside of the first predetermined range.

Abstract: A diagnostic system for a vehicle is disclosed. A first difference module generates a first difference based on a first pressure measured at a first secondary air injection (SAI) valve and a previous value of the first pressure. A first summer module generates a first accumulated difference based on a sum of values of the first difference generated during a predetermined period. A second difference module generates a second difference based on a second pressure measured at a second SAI valve and a previous value of the second pressure. A second summer module generates a second accumulated difference based on a sum of values of the second difference generated during the predetermined period. A fault indication module selectively indicates that a fault is present downstream of one of the first and second SAI valves based on the first and second accumulated differences.

Abstract: A fault diagnostic system of a vehicle includes an error module, a proportional integral (PI) module, and a fault module. The error module determines an error based on a difference between a sample of a signal generated by an exhaust gas oxygen sensor and a target value of the sample. The PI module determines a proportional correction based on the error, determines an integral correction based on the error, and determines a fueling correction based on the proportional and integral corrections. The fault module selectively diagnoses a fault based on the integral correction and the fueling correction.

Abstract: A system for a vehicle includes a change determination module, a sulfur determination module, and a final equivalence ratio (EQR) module. The change determination module estimates a change in an amount of sulfur within a catalyst of an exhaust system of the vehicle. The sulfur determination module estimates the amount of sulfur within the catalyst based on the change. The final EQR module selectively adjusts fueling of an engine based on the amount of sulfur.

Abstract: A diagnostic system for a vehicle is disclosed. A first difference module generates a first difference based on a first pressure measured at a first secondary air injection (SAI) valve and a previous value of the first pressure. A first summer module generates a first accumulated difference based on a sum of values of the first difference generated during a predetermined period. A second difference module generates a second difference based on a second pressure measured at a second SAI valve and a previous value of the second pressure. A second summer module generates a second accumulated difference based on a sum of values of the second difference generated during the predetermined period. A fault indication module selectively indicates that a fault is present downstream of one of the first and second SAI valves based on the first and second accumulated differences.

Abstract: A control system and method for controlling an engine includes a control module. The control module includes an evaporation control valve module closing a canister purge valve during a system diagnostic. A torque determination module determines a torque change for an end of the system diagnostic. A torque adjustment module changes an engine torque to a changed torque corresponding to the torque change. The evaporation control valve module opens the purge valve at the end of the diagnostic.

Abstract: A system for a vehicle includes a change determination module, a sulfur determination module, and a final equivalence ratio (EQR) module. The change determination module estimates a change in an amount of sulfur within a catalyst of an exhaust system of the vehicle. The sulfur determination module estimates the amount of sulfur within the catalyst based on the change. The final EQR module selectively adjusts fueling of an engine based on the amount of sulfur.

Abstract: Fueling to one cylinder of an engine is selectively adjusted based on a correction associated with the cylinder. An instability module increments a counter value when the correction is equal to one of a first predetermined value and a second predetermined value and was previously equal to the other one of the first and second predetermined values. The instability module selectively generates a first indicator based on the counter value. A variance of imbalance values can be determined based on samples of an exhaust gas oxygen signal. Two variances are determined: one variance with adjustment based on the correction, one without adjustment based on the correction. A variance checking module selectively generates a second indicator based on the first and second variances. A re-synchronization module re-synchronizes the imbalance values with the cylinders, respectively, in response to generation of the first indicator and/or the second indicator.

Abstract: A control module and method for an exhaust system of an engine can include a secondary air intake (SAI) pressure module that monitors SAI pressure. An accumulation module can accumulate an SAI string length based on the monitored SAI pressure. A calculation module can determine an average SAI string length based on the accumulated SAI string length. A determination module can determine an operating characteristic of the vehicle exhaust based on the average SAI string length.

Abstract: An engine control system comprises a model pressure determination module and a sensor diagnostic module. The model pressure determination module determines a modeled fuel rail pressure based on an injection duration of a fuel injector and a desired fuel mass injected by the fuel injector. The sensor diagnostic module generates a status of a fuel rail pressure sensor based on a comparison of the modeled fuel rail pressure and a sensed fuel rail pressure.

Abstract: A control system and method for controlling an engine includes a control module. The control module includes an evaporation control valve module closing a canister purge valve during a system diagnostic. A torque determination module determines a torque change for an end of the system diagnostic. A torque adjustment module changes an engine torque to a changed torque corresponding to the torque change. The evaporation control valve module opens the purge valve at the end of the diagnostic.

Abstract: A control system comprising an oxygen sensor that generates an oxygen signal based on an oxygen concentration level in an exhaust gas of an engine, a filtering module that determines a filtered signal based on the oxygen signal, and an air-fuel imbalance detection module that detects an air-fuel imbalance in the engine based on the oxygen signal and the filtered signal. A method comprising generating an oxygen signal based on an oxygen concentration level in an exhaust gas of an engine, determining a filtered signal based on the oxygen signal, and detecting an air-fuel imbalance in the engine based on the oxygen signal and the filtered signal.

Abstract: An engine control system comprises a model pressure determination module and a sensor diagnostic module. The model pressure determination module determines a modeled fuel rail pressure based on an injection duration of a fuel injector and a desired fuel mass injected by the fuel injector. The sensor diagnostic module generates a status of a fuel rail pressure sensor based on a comparison of the modeled fuel rail pressure and a sensed fuel rail pressure.

Abstract: An engine control system includes a driver module and a diagnostics module. The driver module includes a high-side driver and a low-side driver, which selectively actuate a load. The driver module generates status signals based on detection of each of a plurality of failure modes of the high-side and low-side drivers. The diagnostics module increments a first error count for a first mode of the plurality of failure modes when the status signals indicate the driver module has detected the first mode. The diagnostics module increments a corresponding total count each time the driver module analyzes the first mode. The diagnostics module sets a fail state for a diagnostic trouble code (DTC) when the first error count for the first mode reaches a first predetermined threshold prior to the total count reaching a second predetermined threshold.

Abstract: An engine control system includes a driver module and a diagnostics module. The driver module includes a high-side driver and a low-side driver, which selectively actuate a load. The driver module generates status signals based on detection of each of a plurality of failure modes of the high-side and low-side drivers. The diagnostics module increments a first error count for a first mode of the plurality of failure modes when the status signals indicate the driver module has detected the first mode. The diagnostics module increments a corresponding total count each time the driver module analyzes the first mode. The diagnostics module sets a fail state for a diagnostic trouble code (DTC) when the first error count for the first mode reaches a first predetermined threshold prior to the total count reaching a second predetermined threshold.

Abstract: A method and control module for determining a sensor error includes a time-based diagnostic module generating a time-based diagnostic for a sensor and an event-based diagnostic module generating an event-based diagnostic for the sensor. A synchronizing module synchronizes the time-based diagnostic and the event-based diagnostic to obtain a diagnostic result. A fault indicator module generates a fault signal in response to the diagnostic result.

Abstract: A system includes a fuel detection module, a misfire detection module, and a fuel control module. The fuel detection module detects when a fuel supplied to an engine having C cylinders has a high drivability index (HIDI), where C is an integer greater than 1. The misfire detection module detects whether M of the C cylinders misfire when the fuel has the HIDI, where M is an integer, and 1?M<C. The fuel control module injects a first amount of the fuel into the M of the C cylinders when M is less than or equal to D, where D is an integer less than C, and where the first amount is greater than a first predetermined amount.

Abstract: An air/fuel imbalance (AFIM) diagnostic system comprises a first module, an imbalance determination module, and an imbalance diagnostic module. The first module outputs imbalance data samples based on an oxygen signal provided by an oxygen sensor measuring oxygen in exhaust expelled from cylinders of a cylinder bank. The imbalance determination module determines an AFIM value based on the imbalance data samples. The imbalance diagnostic module selectively diagnoses an AFIM in the cylinder bank based on the AFIM value.

Abstract: A control system comprising an oxygen sensor that generates an oxygen signal based on an oxygen concentration level in an exhaust gas of an engine, a filtering module that determines a filtered signal based on the oxygen signal, and an air-fuel imbalance detection module that detects an air-fuel imbalance in the engine based on the oxygen signal and the filtered signal. A method comprising generating an oxygen signal based on an oxygen concentration level in an exhaust gas of an engine, determining a filtered signal based on the oxygen signal, and detecting an air-fuel imbalance in the engine based on the oxygen signal and the filtered signal.

Abstract: A control module and method for an exhaust system of an engine can include a secondary air intake (SAI) pressure module that monitors SAI pressure. An accumulation module can accumulate an SAI string length based on the monitored SAI pressure. A calculation module can determine an average SAI string length based on the accumulated SAI string length. A determination module can determine an operating characteristic of the vehicle exhaust based on the average SAI string length.