Abstract: Methods and systems are provided for an exhaust system. In one example, a method may include determining presence of a zone flow based on a comparison of a first exhaust sensor and a second exhaust sensor. The presence or absence of the zone flow may determine a rate at which an air-fuel ratio is adjusted.

Abstract: Methods and systems are provided for an exhaust system. In one example, a method may include determining presence of a zone flow based on a comparison of a first exhaust sensor and a second exhaust sensor. The presence or absence of the zone flow may determine a rate at which an air-fuel ratio is adjusted.

Abstract: Methods and systems are provided for diagnosing the presence or absence of a catalyst substrate within a catalyst can or housing. The methods and systems described a persistence of excitation metric that is a basis for judging whether or not the catalyst can is empty. If it is determined that the catalyst can or housing is empty, mitigating control actions may be performed via a controller.

Abstract: Methods and systems are provided for catalyst control. In one example, a method may modulate a downstream catalyst by applying a square waveform to an outer feedback control loop. A fuel adjustment is performed in accordance with the square waveform to create an air-fuel ratio oscillation at an upstream catalyst brick and at a downstream catalyst brick.

Abstract: A method for adjusting boost provided via a turbocharger or supercharger is described. In one example, boost is increased in response to a change in road conditions before a driver reacts to the change in road conditions by applying an accelerator pedal. The boost is increased to reduce compressor lag, thereby increasing the responsiveness of the engine and vehicle.

Abstract: Methods and systems are provided for catalyst control. In one example, a method may modulate a downstream catalyst by applying a square waveform to an outer feedback control loop. A fuel adjustment is performed in accordance with the square waveform to create an air-fuel ratio oscillation at an upstream catalyst brick and at a downstream catalyst brick.

Abstract: Methods and systems are provided for diagnosing the presence or absence of a catalyst substrate within a catalyst can or housing. The methods and systems described a persistence of excitation metric that is a basis for judging whether or not the catalyst can is empty. If it is determined that the catalyst can or housing is empty, mitigating control actions may be performed via a controller.

Abstract: Methods and systems are provided for diagnosing operation of a catalyst in the presence of oxygen sensor degradation over a vehicle life cycle. The methods and systems described herein filter the output of one oxygen sensor according to a time constant of a different oxygen sensor so that determination of a catalyst index ratio is compensated for oxygen sensor degradation.

Abstract: Methods and systems are provided for diagnosing operation of a catalyst in the presence of oxygen sensor degradation over a vehicle life cycle. The methods and systems described herein filter the output of one oxygen sensor according to a time constant of a different oxygen sensor so that determination of a catalyst index ratio is compensated for oxygen sensor degradation.

Abstract: A method for adjusting boost provided via a turbocharger or supercharger is described. In one example, boost is increased in response to a change in road conditions before a driver reacts to the change in road conditions by applying an accelerator pedal. The boost is increased to reduce compressor lag, thereby increasing the responsiveness of the engine and vehicle.

Abstract: A system and method are described for reducing NOx emissions following deceleration fuel shut off (DFSO). The method comprises: cutting off fuel to the engine during a deceleration event; open loop operating the engine air/fuel ratio rich of stoichiometry for a predetermined time after the deceleration event; feedback controlling the air/fuel ratio on average near a value rich of stoichiometry for a preselected time after said predetermined time; and feedback controlling the air/fuel ratio returning to stoichiometry after the preselected time.

Abstract: A system and method are described for reducing NOx emissions following deceleration fuel shut off (DFSO). The method comprises: cutting off fuel to the engine during a deceleration event; open loop operating the engine air/fuel ratio rich of stoichiometry for a predetermined time after the deceleration event; feedback controlling the air/fuel ratio on average near a value rich of stoichiometry for a preselected time after said predetermined time; and feedback controlling the air/fuel ratio returning to stoichiometry after the preselected time.