Methods and systems are provided for detecting cylinder-to-cylinder air-fuel ratio (AFR) imbalance in engine cylinders. In one example, a method may include detecting an AFR imbalance of an engine cylinder based on an individual crankshaft acceleration of the cylinder relative to a mean crankshaft acceleration produced by all cylinders of the engine, and correcting a fuel amount of the cylinder via a fuel multiplier value, the fuel multiplier value selected from a plurality of fuel multiplier values based on an imbalance source. In this way, the AFR imbalance may be accurately detected and correcting using existing engine system sensors.

Systems and methods are provided for determining and correcting air/fuel imbalance between cylinders of an internal combustion engine. A deactivation strategy is determined and implemented. An evaluation is made of whether the engine is operating with an air/fuel imbalance between cylinders. When an imbalance is identified, an alternate deactivation strategy is implemented. Based on outcomes of the alternate deactivation strategy, a source cylinder of the air/fuel imbalance is identified, and fuel flow to the source cylinder is corrected.

A method of controlling an air-fuel ratio in a pre-ignition (PI) situation, may include: monitoring, by a PI detector, whether PI occurs in a cylinder of a plurality of cylinders of an engine; and when the PI occurs in the cylinder of the plurality cylinders, controlling, by a controller, an air-fuel ratio of the cylinder in which the PI occurs to be smaller than a theoretical air-fuel ratio, and controlling an air-fuel ratio of a remaining cylinder of the plurality of cylinders in which PI does not occur to be larger than the theoretical air-fuel ratio.

A fuel injection control device and a fuel injection control method for an internal combustion engine according to the present invention correct a basic pulse width by a cylinder-specific correction value that is based on injection variations among fuel injection valves to specify a cylinder-specific pulse width, determine whether or not a split number is acceptable based on a minimum pulse width and a pulse width per one injection calculated from the cylinder-specific pulse width and the split number to modify the split number based on a result of the acceptance determination, modify an acceptance determination reference value which is used in the acceptance determination based on the correction value for each cylinder, and execute split injection based on the split number, the basic pulse width, and the correction value for each cylinder.

Methods and systems are provided for a fuel injector diagnostic. In one example, a method may include modifying an injection pattern to determine a relative fuel mass error of an injector. A fuel injector correction may be determined based the relative fuel mass error.

Methods and systems are provided for detection of cylinder misfire in an engine. In one example, a system may comprise a first cylinder and second cylinder of the engine having exhaust flows combined together in an exhaust system before being combined with other cylinders of the engine. The first cylinder and second cylinder may share an exhaust gas sensor mounted in the exhaust in a position to sense exhaust from the first cylinder and second cylinder, and being positioned before exhaust from other cylinders is combined with sensed exhaust from the first cylinder and second cylinder. The system may further include a control system with instructions stored therein to indicate detected misfire in one or more of the first and second sensors based on an output from the exhaust gas sensor.

A system and method for operating an ICE by (a) generating a running history of one or more-cylinder events per cylinder, and (b) using the running history to select a least-used non-rotating firing pattern, among a plurality of non-rotating firing patterns, provided for each firing fraction less than one (1). By making the least used selection based on the running history, unequal usage among cylinders of the ICE can be mitigated.

When an amount of particulate matters (PM) collected by a gasoline particulate filter (GPF) increases, a control processing unit (CPU) of an engine electronic control unit (ENG ECU) stops combustion control of some cylinders and executes a regeneration process to cause air-fuel ratios of air-fuel mixtures in the remaining cylinders to be richer than a stoichiometric air-fuel ratio. A CPU of a hybrid electric vehicle electronic control unit (HV ECU) increases a target rotation speed of an internal combustion engine when the regeneration process is executed. When executing the regeneration process, the CPU increases a filling efficiency of the internal combustion engine.

Methods and systems are provided for balancing fuel delivery amongst all engine fuel injectors. In one example, a method may include selectively adjusting an injection timing of one or more fuel injectors of a plurality of fuel injectors to increase an inter-injection period between two consecutive fuel injections in response to a request to balance amounts of fuel injected by the plurality of fuel injectors.

A method is disclosed for injecting a gaseous fuel in an internal combustion engine having a combustion chamber and an inlet valve assigned to the combustion chamber. The method includes determining a torque output of the combustion chamber, specifying a comparative value for the torque output, and determining a difference between the torque output and the comparative value. When the difference is less than a given threshold value, the method reduces a first injection quantity of the gaseous fuel depending on the determined difference, which is injected temporally before the inlet valve is closed. When the difference is greater than the given threshold value, the method increases the first injection quantity of the gaseous fuel depending on the determined difference. Also described is a device which may carry out the method.