Methods and systems are provided for reducing a spark plug soot load and a combustion chamber soot load by controlling spark plug timing while injecting water or washer fluid. In one example, water or washer fluid is injected during a torque reduction while advancing spark timing so as to provide at least a portion of the torque reduction while opportunistically cleaning soot from the spark plug and combustion chamber. By reducing spark plug soot load, misfire occurrence is reduced, while pre-ignition occurrence is reduced by decarbonizing the combustion chamber.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, valves of a cylinder are deactivated in a closed state in response to an indication of degradation of a valve of the cylinder. Further, fuel flow to the cylinder may be stopped via ceasing to inject fuel to the cylinder.

Methods and systems are provided to determine air-fuel imbalance of cylinders in a variable displacement engine. In one example, the method may include during a cylinder deactivation event, sequentially deactivating each cylinder of a cylinder group including two or more cylinders and estimating a lambda deviation for each cylinder following the sequential deactivation of each cylinder of the cylinder group; and learning an air error for each cylinder based on the estimated lambda deviation.

A variable displacement controller for deactivating one or more cylinder assemblies of a vehicle engine can include a processor for performing various operations and the operations can include: receiving data indicative of a requested torque and vehicle speed, determining a torque variable timer threshold value based on the received data indicative of requested torque and vehicle speed, initiating a timer, comparing the timer value to the variable timer threshold value, and selectively activating/deactivating at least one of the engine cylinder assemblies based on the comparison between the timer value and the variable timer threshold value. At least one of the engine cylinder assemblies is activated if the timer value is less than the variable timer threshold value, and at least one of the engine cylinder assemblies is deactivated if the timer value is greater than or equal to the variable timer threshold value.

An abnormality determination device includes an injection instructor that realizes a rich state of an air-fuel ratio in an exhaust gas by sending an instruction of (i) stopping an application of bias to a plus terminal and (ii) adjusting a fuel injection amount from an injector, and an abnormality determiner that distinctively determines abnormality of, i.e., in terms of which one of, the plus terminal or a minus terminal having a sky failure or a ground failure by detecting an electromotive force of an air-fuel ratio sensor when the air-fuel ratio in the exhaust gas is in the rich state according to the instruction of the injection instructor.

A system and method for detecting and mitigating automatic ignition in a cylinder of an internal combustion engine. The method includes providing a first sensor for sensing and determining a crank angle of a crankshaft of the engine. A second sensor is provided for detecting a change in an engine vibration frequency caused by Auto Ignition (AI). The engine vibration signal of the second sensor is processed into a knock intensity signal. The knock intensity signal is indicative of the cylinder pressure and is acquired when the crank angle is between a first predetermined crank angle and a second predetermined crank angle. At least one characteristic of the knock intensity signal is determined and the at least one characteristic of the knock intensity signal is compared to at least one predetermined characteristic threshold. If the at least one characteristic of the knock intensity signal is determined to exceed the at least one predetermined characteristic threshold, then at least one auto ignition mitigating action is performed to mitigate the auto ignition event.

A method and system for controlling a fuel pressure valve of a vehicle are disclosed. The disclosed control method includes engine start entrance for controlling a controller to increase an allowable deviation between a current target fuel pressure and an actual fuel pressure when an ignition switch-on signal is received by the controller, fuel pressure determination for controlling the controller to determine whether a deviation value between the target fuel pressure and an actual fuel pressure measured by a sensor is greater than an allowable deviation, and valve control for controlling the controller to determine a duty value for control of opening of the fuel pressure valve, and then controlling the controller to open the fuel pressure valve using the determined duty value, thereby decreasing the actual fuel pressure.

A fuel injection control unit includes: a first transience determination unit which determines an accelerating state when the first intake pressure differential integration value in a section including a compression stroke, an expansion stroke and an exhaust stroke is greater than a first acceleration determination threshold value; a first transient fuel injection amount calculation unit which calculates an additional fuel injection amount on the basis of the first intake pressure differential integration value; a second transience determination unit which determines an accelerating state when the second intake pressure differential integration value in a section including an intake stroke is greater than a second acceleration determination threshold value which is smaller than the first acceleration determination threshold value; and a second transient fuel injection amount calculation unit which calculates an additional fuel injection amount on the basis of the second intake pressure differential integration value.

A control system of an internal combustion engine which performs diffusion combustion by compression autoignition on fuel injected in a main injection in at least a partial operating range and which performs stratified combustion by spark ignition using a spark plug on fuel injected prior to the main injection. The control system determines whether or not the diffusion combustion occurs and performs combustion by spark ignition using the spark plug on the fuel injected in the main injection when it is determined that the diffusion combustion does not occur.

A remaining fuel amount warning device for a vehicle, the remaining fuel amount warning device giving a warning that an amount of fuel remaining in a fuel tank is smaller than a predetermined value on the basis of output of a fuel gauge measuring the remaining fuel amount, includes combustion state changing device for changing the combustion state of an engine. When the remaining fuel amount becomes smaller than the predetermined value, the remaining fuel amount warning device performs remaining amount warning control that produces vibration different than during normal operation by changing the combustion state of the engine by the combustion state changing device. A starter switch for starting the engine is made to serve also as a warning acknowledging button for stopping the remaining amount warning control for a predetermined time on the basis of an operation by an occupant.