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 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 an engine includes a stage transition module and a control module. The stage transition module generates a command signal based on a fuel control signal. The command signal commands a fuel system of the engine to intrusively transition between rich and lean states during a diagnostic test that includes first, second, and third stages. The first, second, and third stages are defined based on transitions between the rich and lean states. The control module during the second and third stages detects: an error with a first oxygen sensor based on a comparison between the command signal and a first oxygen signal from the first oxygen sensor; an error with a second oxygen sensor based on a second oxygen signal from the second oxygen sensor; and an error with a catalytic converter based on the first and second oxygen signals and a manifold absolute pressure signal.

Abstract: A diagnostic system for an exhaust system of an engine includes a fuel control module and a diagnostic module. The fuel control module, in response to a request for a fuel inhibiting event, operates the engine in a first rich condition for a first period until a catalytic converter of the exhaust system is in a predetermined first rich state and subsequently operates the engine in a lean condition for a second period contiguous with the first period. The diagnostic module determines a catalyst efficiency of the catalytic converter based on an output of an oxygen sensor located downstream of said catalytic converter during the second period, and selectively adjusts a diagnostic status of the catalytic converter based on a comparison of the catalyst efficiency and a predetermined catalyst efficiency. The fuel inhibiting event may be a deceleration fuel-cutoff event. A related diagnostic method is also provided.

Abstract: An engine control module includes a spark control module, an engine speed module, a residual determination module, and a metric determination module. The spark control module actuates spark plugs based on a commanded spark timing. The engine speed module determines a desired engine speed based on an engine temperature and a period of time an engine is in operation after a cold start. The residual determination module determines a desired spark timing based on the desired engine speed, and determines a residual spark timing based on a difference between the commanded spark timing and the desired spark timing. The metric determination module detects a spark timing fault based on the residual spark timing and a predetermined spark timing range.

Abstract: A diagnostic system for an exhaust system of an engine includes a fuel control module and a diagnostic module. The fuel control module, in response to a request for a fuel inhibiting event, operates the engine in a first rich condition for a first period until a catalytic converter of the exhaust system is in a predetermined first rich state and subsequently operates the engine in a lean condition for a second period contiguous with the first period. The diagnostic module determines a catalyst efficiency of the catalytic converter based on an output of an oxygen sensor located downstream of said catalytic converter during the second period, and selectively adjusts a diagnostic status of the catalytic converter based on a comparison of the catalyst efficiency and a predetermined catalyst efficiency. The fuel inhibiting event may be a deceleration fuel-cutoff event. A related diagnostic method is also provided.

Abstract: A diagnostic system for an engine includes a stage transition module and a control module. The stage transition module generates a command signal based on a fuel control signal. The command signal commands a fuel system of the engine to intrusively transition between rich and lean states during a diagnostic test that includes first, second, and third stages. The first, second, and third stages are defined based on transitions between the rich and lean states. The control module during the second and third stages detects: an error with a first oxygen sensor based on a comparison between the command signal and a first oxygen signal from the first oxygen sensor; an error with a second oxygen sensor based on a second oxygen signal from the second oxygen sensor; and an error with a catalytic converter based on the first and second oxygen signals and a manifold absolute pressure signal.

Abstract: A diagnostic system for an exhaust system including a catalyst and a post-catalyst oxygen sensor is provided. The system generally includes a fuel control module that commands fuel to transition from a rich condition to a lean condition and that commands fuel to transition from the lean condition to the rich condition. A first diagnostic module monitors the post-catalyst oxygen sensor during the transition from the rich condition to the lean condition. A second diagnostic module monitors the catalyst during the transition from the lean condition to the rich condition.

Abstract: An engine control module includes a spark control module, an engine speed module, a residual determination module, and a metric determination module. The spark control module actuates spark plugs based on a commanded spark timing. The engine speed module determines a desired engine speed based on an engine temperature and a period of time an engine is in operation after a cold start. The residual determination module determines a desired spark timing based on the desired engine speed, and determines a residual spark timing based on a difference between the commanded spark timing and the desired spark timing. The metric determination module detects a spark timing fault based on the residual spark timing and a predetermined spark timing range.

Abstract: A diagnostic system for an exhaust system including a catalyst and a post-catalyst oxygen sensor is provided. The system generally includes a fuel control module that commands fuel to transition from a rich condition to a lean condition and that commands fuel to transition from the lean condition to the rich condition. A first diagnostic module monitors the post-catalyst oxygen sensor during the transition from the rich condition to the lean condition. A second diagnostic module monitors the catalyst during the transition from the lean condition to the rich condition.