Abstract: Systems and methods for estimating a temperature of an after treatment device in an exhaust system of an engine are described. In one example, the temperature is estimated during condition when an engine exits a fuel cut-out mode and excess fuel is delivered to the after treatment device for the purpose of increasing after treatment device efficiency.

Abstract: Methods and systems are provided for adapting a target impedance of an oxygen sensor. In one example, a method may include updating a target impedance of an oxygen sensor based on a difference between an estimated voltage across a sensing element of the oxygen sensor and a reference RMS voltage of the sensing element. The temperature of the oxygen sensor may be adjusted based on the updated target impedance.

Abstract: Systems and methods for estimating a temperature of an after treatment device in an exhaust system of an engine are described. In one example, the temperature is estimated during condition when an engine is in a fuel cut-out mode and fuel vapors are being released to the engine via a fuel vapor storage canister.

Abstract: Systems and methods for estimating a temperature of an after treatment device in an exhaust system of an engine are described. In one example, the temperature is estimated during condition when an engine is in a fuel cut-out mode and fuel vapors are being released to the engine via a fuel vapor storage canister.

Abstract: Systems and methods for estimating a temperature of an after treatment device in an exhaust system of an engine are described. In one example, the temperature is estimated during condition when an engine exits a fuel cut-out mode and excess fuel is delivered to the after treatment device for the purpose of increasing after treatment device efficiency.

Abstract: A method for adjusting an air-fuel ratio of a turbocharged engine that operates without blow though and with blow through is disclosed. In one example, the method provides a way to provide a feed forward fuel adjustment in the presence of engine blow though so that a closed loop controller does not have to exceed its range of control authority.

Abstract: Systems and methods for operating an engine that includes an oxygen sensor and one or more fuel injectors for each engine cylinder are described. In one example, lines describing a relationship between a fuel mass multiplier and a coefficient of a function describing output of an oxygen sensor to a step change in fuel mass are a basis for determining air-fuel imbalance of engine cylinders.

Abstract: A method for adjusting an air-fuel ratio of a turbocharged engine that operates without blow though and with blow through is disclosed. In one example, the method provides a way to provide a feed forward fuel adjustment in the presence of engine blow though so that a closed loop controller does not have to exceed its range of control authority.

Abstract: Systems and methods for operating an engine that includes an oxygen sensor and one or more fuel injectors for each engine cylinder are described. In one example, lines describing a relationship between a fuel mass multiplier and a coefficient of a function describing output of an oxygen sensor to a step change in fuel mass are a basis for determining air-fuel imbalance of engine cylinders.

Abstract: Methods and systems are provided for converting an asymmetric sensor response of an exhaust gas sensor to a symmetric response. In one example, a method includes adjusting fuel injection responsive to a modified exhaust oxygen feedback signal from an exhaust gas sensor, where the modified exhaust oxygen feedback signal is modified by transforming an asymmetric response of the exhaust gas sensor to a symmetric response. Further, the method may include adapting parameters of an anticipatory controller of the exhaust gas sensor based on the modified symmetric response.

Abstract: Methods and systems are provided for converting an asymmetric sensor response of an exhaust gas sensor to a symmetric response. In one example, a method includes adjusting fuel injection responsive to a modified exhaust oxygen feedback signal from an exhaust gas sensor, where the modified exhaust oxygen feedback signal is modified by transforming an asymmetric response of the exhaust gas sensor to a symmetric response. Further, the method may include adapting parameters of an anticipatory controller of the exhaust gas sensor based on the modified symmetric response.

Abstract: Systems and methods for determining air-fuel error in an engine fueled via direct and port fuel injection. Errors associated with individual fuel injection systems are distinguished from a common error based on trends in the error correction coefficients of the individual fuel injection systems. Adaptive fuel multipliers for each injection system are updated to account for the common error.

Abstract: Systems and methods for determining air-fuel error in an engine fueled via direct and port fuel injection. Errors associated with individual fuel injection systems are distinguished from a common error based on trends in the error correction coefficients of the individual fuel injection systems. Adaptive fuel multipliers for each injection system are updated to account for the common error.

Abstract: Systems and methods for determining air-fuel error in an engine fueled via direct and port fuel injection. Errors associated with individual fuel injection systems are distinguished from a common error based on trends in the error correction coefficients of the individual fuel injection systems. Adaptive fuel multipliers for each injection system are updated to account for the common error.

Abstract: Systems and methods for determining air-fuel error in an engine fueled via direct and port fuel injection. Errors associated with individual fuel injection systems are distinguished from a common error based on trends in the error correction coefficients of the individual fuel injection systems. Adaptive fuel multipliers for each injection system are updated to account for the common error.

Abstract: Methods and systems are provided for estimating an exhaust air/fuel ratio based on outputs from an exhaust oxygen sensor. In one example, a method may include adjusting engine operation based on an air-fuel ratio estimated based on an output of the exhaust oxygen sensor and a learned correction factor. For example, the oxygen sensor may operate in a variable voltage mode in which a reference voltage of the oxygen sensor may be adjusted between a lower first voltage and a higher second voltage, and the learned correction factor is based on the second voltage.

Abstract: Methods and systems are provided for estimating an exhaust air/fuel ratio based on outputs from an exhaust oxygen sensor. In one example, a method may include adjusting engine operation based on an air-fuel ratio estimated based on an output of the exhaust oxygen sensor and a learned correction factor. For example, the oxygen sensor may operate in a variable voltage mode in which a reference voltage of the oxygen sensor may be adjusted between a lower first voltage and a higher second voltage, and the learned correction factor is based on the second voltage.

Abstract: Methods and systems are provided reusing processed sensor data to identify multiple types of sensor degradation. In one example, a central peak of a distribution, such as a generalized extreme value distribution, of sensor readings is re-used to identify asymmetric sensor degradation and stuck in-range sensor degradation.

Abstract: Methods and systems are provided for estimating an exhaust air/fuel ratio based on outputs from an exhaust oxygen sensor. In one example, a method may include adjusting engine operation based on an air-fuel ratio estimated based on an output of the exhaust oxygen sensor and a learned correction factor. For example, the oxygen sensor may operate in a variable voltage mode in which a reference voltage of the oxygen sensor may be adjusted between a lower first voltage and a higher second voltage, and the learned correction factor is based on the second voltage.

Abstract: Methods and systems are described for evaluating presence of fuel shifts in an engine. In one example, a method comprises indicating a fuel shift based on a time delay of an exhaust gas sensor during an entry into and an exit out of deceleration fuel shut off (DFSO).