Abstract: Methods and systems are provided for an aftertreatment system. In one example, a system comprising a spark-ignited engine comprising a selective catalytic reduction device (SCR) arranged in an exhaust passage downstream of a catalyst, and an injector positioned to inject a reductant directly into the exhaust passage downstream of the catalyst subsequent an engine shut-off event.

Abstract: Methods and systems for operating an engine with split lambda modes are provided. At least one example method comprises, while operating an engine in a condition that is within a resonant frequency region for a default split lambda mode, carrying out a rolling split lambda mode. The engine may be operated with only stoichiometric engine cycles in the default split lambda mode, the stoichiometric engine cycles including enleaned and enriched cylinders. Further, the engine may be operated with a plurality of non-stoichiometric engine cycles when carrying out the rolling split lambda mode, the plurality of non-stoichiometric engine cycles including at least one rich engine cycle and at least one lean engine cycle.

Abstract: Methods and systems for operating an engine with split lambda modes are provided. At least one example method comprises, while operating an engine in a condition that is within a resonant frequency region for a default split lambda mode, carrying out a rolling split lambda mode. The engine may be operated with only stoichiometric engine cycles in the default split lambda mode, the stoichiometric engine cycles including enleaned and enriched cylinders. Further, the engine may be operated with a plurality of non-stoichiometric engine cycles when carrying out the rolling split lambda mode, the plurality of non-stoichiometric engine cycles including at least one rich engine cycle and at least one lean engine cycle.

Abstract: Methods and systems for engine operation are provided. In at least one example method, the method comprises, while operating an engine with at least one lean cylinder and at least one rich cylinder, delivering fuel to the at least one lean cylinder via direct fuel injection (DI) and delivering fuel to the at least one rich cylinder via port fuel injection (PFI).

Abstract: Methods and systems for engine operation are provided. In at least one example method, the method comprises, while operating an engine with at least one lean cylinder and at least one rich cylinder, delivering fuel to the at least one lean cylinder via direct fuel injection (DI) and delivering fuel to the at least one rich cylinder via port fuel injection (PFI).

Abstract: Methods and systems are provided for improving fuel economy and reducing undesired emissions. In one example, a method may include in response to an engine speed being within a first threshold speed of an engine idle speed during a speed reduction request with engine cylinders unfueled, maintaining the cylinders unfueled, and controlling the engine to a desired stopping position responsive to the engine speed being greater than a second threshold speed lower than the idle speed. In this way, fuel usage and emissions may be reduced and engine restart requests may be conducted at least in part via vehicle inertia.

Abstract: Systems and methods for operating a vehicle that includes a starter motor are described. In one example, the starter motor may engage a flywheel of an engine and rotate the engine without starting the engine in response to a request to move the vehicle without starting the engine. The starter motor may provide the propulsive force to move the vehicle a short distance.

Abstract: Methods and systems are provided for increasing an amount of oxygen in a pre-chamber of a cylinder prior to combustion. In one example, a method may include purging residual gases from a pre-chamber to a cylinder via a pre-chamber air injection, and reducing a flow of the oxygen from the pre-chamber to the cylinder via a cylinder fuel injection directed toward an orifice fluidically connecting the pre-chamber with the cylinder. In this way, a composition of pre-chamber gases may be adjusted during a combustion cycle of a cylinder.

Abstract: Methods and systems for adjusting timing of fuel injectors to reduce cylinder to cylinder air-fuel maldistribution are disclosed. In one example, fuel injection timing is adjusted as a function of pressure ratios that are based on fuel rail pressures observed during injection of fuel. The pressure ratio may be a ratio of a root-mean-square pressure and a scheduling fuel pressure.

Abstract: Methods and systems are provided for controlling engine knock. In one example, a method may include decreasing intake valve lift at a first set of cylinders where knock is indicated and increasing intake valve lift at a second set of cylinders where knock is not indicated. A stoichiometric air-to-fuel ratio is thereby maintained.

Abstract: Systems and methods for cooling an internal combustion engine via flowing air through the internal combustion engine during select conditions are presented. In one example, lift of intake and/or exhaust poppet valves may be adjusted as a function of engine temperature. In addition, opening and closing timings of intake and exhaust poppet valves may be adjusted as a function of engine temperature.

Abstract: Systems and methods for cooling an internal combustion engine via flowing air through the internal combustion engine during select conditions are presented. In one example, lift of intake and/or exhaust poppet valves may be adjusted as a function of engine temperature. In addition, opening and closing timings of intake and exhaust poppet valves may be adjusted as a function of engine temperature.

Abstract: Methods and systems are provided for injector correction learned while a direct injector delivers fuel as a group of fuel injections per cylinder event. The correction is learned using a pressure based injector balancing approach while relies on a sensed pressure drop across the group of fuel injections. Errors for individual pulses of the group of injections is learned as a function of inter-injection spacing and individual pulse-width commands.

Abstract: Methods and systems for operating an engine with split lambda modes are provided. At least one example method comprises, calculating a stoichiometric torque output of the plurality of cylinders; then applying one or more lean torque modifiers for every lean cylinder of the one or more non-stoichiometric cylinders to the stoichiometric torque output to calculate a lean torque output. In at least one example, one or more rich torque modifiers for every rich cylinder of the one or more non-stoichiometric cylinders may be applied to the stoichiometric torque output to calculate a rich torque output. Further, the lean torque output and the rich torque output may be summed to calculate a total engine torque output.

Abstract: Methods and systems are provided for controlling fuel injection to cylinders of an engine in a vehicle. In one example, a method comprises monitoring an electrical energy profile associated with a fuel injector that has been commanded to inject a predetermined amount of a fuel into an engine cylinder, inferring a fuel injection pressure based on the electrical energy profile, and controlling a subsequent fuel injection based on the inferred fuel injection pressure. In this way, fuel injection may be controlled without relying on a pressure sensor in a fuel rail that supplies fuel to the fuel injector, under conditions where the fuel rail does not include the pressure sensor or where the pressure sensor is degraded.

Abstract: Methods and systems are disclosed for operating an engine that includes fuel injectors that supply fuel to cylinders of the engine. According to the methods and system, variation of individual fuel injection amounts injected by a sole fuel injector are determined so that it may be determined if individual fuel injector variation may be contributing to engine air-fuel ratio variation.

Abstract: Methods and systems are provided for restarting an engine following an engine idle-stop. In one example, a method may include upon receiving an engine restart request during an engine idle-stop, initiating combustion in a selected cylinder and based on a predicted time of attainment of peak pressure in the cylinder, activating a starter motor.

Abstract: Methods and systems are provided for injector correction learned while a direct injector delivers fuel as a group of fuel injections per cylinder event. The correction is learned using a pressure based injector balancing approach while relies on a sensed pressure drop across the group of fuel injections. Errors for individual pulses of the group of injections is learned as a function of inter-injection spacing and individual pulse-width commands.

Abstract: Methods and systems are provided for operating an electric motor to drive either a transmission fluid pump or a direct injection fuel pump. In one example, a method may include operating an electric motor to drive a direct injection fuel pump to supply fuel to a direct injection fuel rail while an engine of a start/stop vehicle is on, and operating the electric motor to drive an auxiliary transmission fluid pump to circulate transmission fluid to a transmission rotationally coupled to the engine while the engine is off during an auto-stop. In this way, the direct injection fuel pump may be electrically driven without increasing vehicle costs through adding an additional electric motor.

Abstract: Methods and systems are provided for operating an engine to diagnose and compensate for cylinder imbalance in an engine. In one example, a method may include diagnosing a torque imbalance in a multi-cylinder engine by operating the engine at a lean air-fuel ratio (AFR) while an amount of ammonia stored in an selective catalytic reduction (SCR) system is greater than a threshold amount and a temperature of the engine is greater than a threshold temperature; and responsive to the diagnosed torque imbalance, adjusting fueling and spark timing for each cylinder, the adjustments based on an AFR offset of each cylinder determined while adjusting the lean AFR.