Methods and systems are provided for diagnosing a degraded fuel injector delivering undesired additional fuel in a variable displacement engine. In one example, a method includes, responsive to an indication of a cylinder air-fuel imbalance, deactivating a subset of cylinders of a multi-cylinder engine, performing a power balance test to determine an output of each cylinder after a duration of deactivation, and indicating that a deactivated cylinder has a degraded fuel injector responsive to the output being lower than a threshold output.

Methods and systems are provided for diagnostics of a wastegate valve during vehicle-off conditions. In one example, the engine may be reverse rotated, unfueled, and air flow via the intake manifold may be estimated and compared to a baseline air flow. A stuck open wastegate valve may be indicated based on the comparison between the intake air flow and the baseline air flow.

Methods and systems for evaluating whether or not a fuel amount that is greater than a threshold has been release to an engine via fuel injectors when the fuel injectors are commanded off are presented. In one example, an oxygen sensor is activated and engine cranking is prevented until a pumping current of the oxygen sensor is proportionate to a concentration of oxygen sensed via the oxygen sensor so that released fuel may be observed during engine starting.

An engine device including an engine capable of coping with both a premix combustion mode in which premixed fuel obtained by mixing fuel with air in advance is supplied into a cylinder and combusted and a diffusion combustion mode in which liquid fuel is injected into the cylinder and combusted. The engine device further includes a gas supply device configured to supply the gaseous fuel into the cylinder in the premix combustion mode; a pilot injection device configured to inject the liquid fuel into the cylinder in the premix combustion mode; and a main injection device configured to inject the liquid fuel into the cylinder in the diffusion combustion mode. The liquid fuel is injected from the main injection device and the liquid fuel is injected from the pilot injection device during the diffusion combustion mode, thus diagnosing failure in the pilot injection device.

Methods and systems are provided for diagnosing degradation of an exhaust valve coupled to an engine cylinder. In one example, a method may include, routing compressed air from an electric booster into a cylinder with the intake valve of the cylinder open and the exhaust valve closed, and indicating degradation of the exhaust valve based on an exhaust airflow relative to a baseline airflow.

Methods and systems are provided for drying engine cylinders in situ responsive to engine flooding. In one example, a laser ignition device is operated in each engine cylinder, sequentially, while the cylinder is parked with an intake valve closed and an exhaust valve open. The heat generated by the laser operation vaporizes liquid fuel in the cylinder, which flows out of the cylinder via the open exhaust valve, expediting cylinder drying.

Various methods and systems are provided for diagnosing a condition of a fuel injector of an engine. In one example, a method for an engine includes injecting a first pulse of fuel as a first pilot injection into a first subset of cylinders of a plurality of engine cylinders, where the first pilot injection precedes a primary injection of fuel into the first subset of cylinders by a duration; correlating a first response in an engine operating parameter to the first pilot injection; and adjusting the primary injection of fuel into the first subset of cylinders based on the first response. In one example, the first pilot injection precedes the primary injection by a predefined short duration and the primary injection of fuel is adjusted within a predefined or preset upper limit and lower limit.

Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

The invention relates to a control method for controlling a fuel injection system (10) of an internal combustion engine, wherein, wherein, in a fault situation of the fuel injection system (10), a camshaft angle of a camshaft (34) which drives a pump piston (32) of a high-pressure fuel pump (14) of the fuel injection system (10) is adjusted such that an injection time (tI) of injector valve (42) which injects the fuel from the fuel injection system (10) into a combustion chamber of the internal combustion engine lies in a pressure trough (50) of a pressure oscillation in a high-pressure region (16).

An EGR valve includes a valve seat in a flow passage of a housing, a valve element seatable on the valve seat, a rotary shaft to open or close the valve element, a motor and a speed reducing mechanism, a return spring urging the valve element in a valve closing direction, and an opening-degree sensor to detect an opening degree of the valve element. An electronic control unit (ECU) diagnoses abnormality due to lodging of foreign matter between the valve seat and the valve element during full close. When driving the motor to urge the valve element in the valve closing direction during full close of the valve element, the ECU determines the EGR valve to be abnormal because of lodging of foreign matter if a difference between a value detected by the opening-degree sensor and a predetermined reference value is larger than a first determination value.