Abstract: Methods and systems are provided for tracking a fuel puddle mass in the intake port of a deactivated engine cylinder. The difference in fuel evaporation rate in the deactivated cylinder intake is accounted for by applying distinct time constant and gain values to a transient fuel compensation model. A fuel vapor content is clipped once the intake vapor pressure in the intake port of the deactivated cylinder reaches a saturation pressure limit.

Abstract: Methods and systems are provided for learning fuel injector error for cylinder groups during a deceleration fuel shut-off (DFSO), where all cylinders of an engine are deactivated, sequentially firing each cylinder of a cylinder group, each cylinder fueled via consecutive first and second fuel pulses of differing fuel pulse width from an injector. Based on a lambda deviation between the first and second pulses, a fuel error for the injector and an air-fuel ratio imbalance for each cylinder is learned. Alternatively or additionally, a difference in crankshaft acceleration between the first and second pulses relative to the expected deviation may be used to learn torque error, and adjust fuel injector error and air-ratio imbalance for each cylinder.

Abstract: Methods and systems are provided for calibrating engine port injectors. After pressurizing a low pressure fuel rail, a lift pump may be disabled and port injector variability may be correlated with a measured fuel rail pressure drop at each port injection event by sweeping injection pressure while maintaining injection voltage, and then sweeping injection voltage while maintaining injection pressure. A port injector variability map learned as a function of injection voltage and injection pressure is then transformed into a map learned as a function of injection current and injection pressure by accounting for injector variability caused due to changes in injector temperature.

Abstract: Methods and systems are provided for tracking a fuel puddle mass in the intake port of a deactivated engine cylinder. The difference in fuel evaporation rate in the deactivated cylinder intake is accounted for by applying distinct time constant and gain values to a transient fuel compensation model. A fuel vapor content is clipped once the intake vapor pressure in the intake port of the deactivated cylinder reaches a saturation pressure limit.

Abstract: Methods and systems are provided for tracking a fuel puddle mass in the intake port of a deactivated engine cylinder. The difference in fuel evaporation rate in the deactivated cylinder intake is accounted for by applying distinct time constant and gain values to a transient fuel compensation model. A fuel vapor content is clipped once the intake vapor pressure in the intake port of the deactivated cylinder reaches a saturation pressure limit.

Abstract: Systems and methods for operating an internal combustion engine based on output of an intake manifold pressure sensor and output of an in cylinder pressure sensor are described. The systems and methods provide a way of determining cylinder air charge so that a fuel injector has sufficient time to provide a desired amount of fuel to a cylinder during a cycle of the cylinder.

Abstract: Methods and systems are provided for learning fuel injector error for cylinder groups during a deceleration fuel shut-off (DFSO), where all cylinders of an engine are deactivated, sequentially firing each cylinder of a cylinder group, each cylinder fueled via consecutive first and second fuel pulses of differing fuel pulse width from an injector. Based on a lambda deviation between the first and second pulses, a fuel error for the injector and an air-fuel ratio imbalance for each cylinder is learned. Alternatively or additionally, a difference in crankshaft acceleration between the first and second pulses relative to the expected deviation may be used to learn torque error, and adjust fuel injector error and air-ratio imbalance for each cylinder.

Abstract: Methods and systems are provided for calibrating engine port injectors. After pressurizing a low pressure fuel rail, a lift pump may be disabled and port injector variability may be correlated with a measured fuel rail pressure drop at each port injection event by sweeping injection pressure while maintaining injection voltage, and then sweeping injection voltage while maintaining injection pressure. A port injector variability map learned as a function of injection voltage and injection pressure is then transformed into a map learned as a function of injection current and injection pressure by accounting for injector variability caused due to changes in injector temperature.

Abstract: Systems and methods for operating an internal combustion engine based on output of an intake manifold pressure sensor and output of an in cylinder pressure sensor are described. The systems and methods provide a way of determining cylinder air charge so that a fuel injector has sufficient time to provide a desired amount of fuel to a cylinder during a cycle of the cylinder.

Abstract: Methods and systems are provided for tracking a fuel puddle mass in the intake port of a deactivated engine cylinder. The difference in fuel evaporation rate in the deactivated cylinder intake is accounted for by applying distinct time constant and gain values to a transient fuel compensation model. A fuel vapor content is clipped once the intake vapor pressure in the intake port of the deactivated cylinder reaches a saturation pressure limit.

Abstract: Methods and systems are provided for learning fuel injector error for cylinder groups during a deceleration fuel shut-off (DFSO), where all cylinders of an engine are deactivated, sequentially firing each cylinder of a cylinder group, each cylinder fueled via consecutive first and second fuel pulses of differing fuel pulse width from an injector. Based on a lambda deviation between the first and second pulses, a fuel error for the injector and an air-fuel ratio imbalance for each cylinder is learned. Alternatively or additionally, a difference in crankshaft acceleration between the first and second pulses relative to the expected deviation may be used to learn torque error, and adjust fuel injector error and air-ratio imbalance for each cylinder.

Abstract: Systems and methods for improving fuel injection of an engine that includes a cylinder receiving fuel from two different fuel injectors is disclosed. In one example, a transfer function or gain of a direct fuel injector is adjusted in response to an exhaust lambda value and a first pulse width of two pulse widths provided to an injector of a cylinder during a cylinder cycle.

Abstract: Methods and systems are provided for controlling individual cylinder air-fuel ratio (AFR) in a combustion engine. In one example, a method may include measuring a high-frequency exhaust gas composition, parsing the measured high-frequency exhaust gas composition to determine a first cylinder-specific component of the high-frequency exhaust gas composition, estimating an air-fuel ratio (AFR) based on the first cylinder-specific component of the measured high-frequency exhaust gas composition, and correcting the estimated AFR by subtracting intercylinder exhaust gas interactions from the estimated AFR.

Abstract: Methods and systems are provided for adjusting engine operating conditions for reduction of NOx emissions. In one example, immediately after a fuel shut-off event, in response to an oxygen content of an exhaust catalyst being higher than a threshold, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection. By increasing manifold cooling, NOx production may be reduced.

Abstract: Methods and systems are provided for calibrating engine port injectors. After pressurizing a low pressure fuel rail, a lift pump may be disabled and port injector variability may be correlated with a measured fuel rail pressure drop at each port injection event by sweeping injection pressure while maintaining injection voltage, and then sweeping injection voltage while maintaining injection pressure. A port injector variability map learned as a function of injection voltage and injection pressure is then transformed into a map learned as a function of injection current and injection pressure by accounting for injector variability caused due to changes in injector temperature.

Abstract: Methods and systems are provided for calibrating engine port injectors. After pressurizing a low pressure fuel rail, a lift pump may be disabled and port injector variability may be correlated with a measured fuel rail pressure drop at each port injection event by sweeping injection pressure while maintaining injection voltage, and then sweeping injection voltage while maintaining injection pressure. A port injector variability map learned as a function of injection voltage and injection pressure is then transformed into a map learned as a function of injection current and injection pressure by accounting for injector variability caused due to changes in injector temperature.

Abstract: Methods and systems are provided for adjusting engine operating conditions for reduction of NOx emissions. In one example, immediately after a fuel shut-off event, in response to an oxygen content of an exhaust catalyst being higher than a threshold, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection. By increasing manifold cooling, NOx production may be reduced.

Abstract: Methods and systems are provided for adjusting engine operating conditions for mitigation of pre-ignition in one or more engine cylinder. In one example, a method may include, in response to indication of pre-ignition, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection, while maintaining engine operation at or around a stoichiometric air-fuel ratio.

Abstract: Methods and systems are provided for adjusting engine operating conditions for mitigation of pre-ignition in one or more engine cylinder. In one example, a method may include, in response to indication of pre-ignition, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection, while maintaining engine operation at or around a stoichiometric air-fuel ratio.

Abstract: Methods and systems are provided for leveraging the charge cooling effect of a manifold fuel injection. A charge cooling effect of a scheduled manifold fuel injection may be predicted based on feedback received from a manifold charge temperature sensor during a preceding manifold injection event. If sufficient charge cooling is not predicted, the manifold fuel injection is temporarily disabled.