Systems and methods for controlling knock in an internal combustion engine are presented. In one example, spark timing is retarded in engine cylinders where engine knock is indicated and spark is subsequently advanced after it has been retarded. The rate spark timing is advanced may be based on a way engine cylinders have been deactivated.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, fuel supplied to cylinders being reactivated is supplied by direct fuel injectors even though the engine is operating in a region (e.g., speed and torque) where under conditions where cylinders are not being reactivated the engine injects fuel solely via port fuel injectors.

Systems and methods for operating an engine with deactivating valves are presented. In one example, deactivated valves may be reactivated to increase a rate of camshaft phase indexing relative to engine crankshaft position. However, if a desired rate of camshaft indexing is low, the engine cylinders may remain deactivated based on the low rate of desired camshaft indexing.

Methods and systems are provided for adjusting a location of a fuel injection in response to a substitution rate and a desired EGR flow. In one example, a method may include injecting a first fuel to a combustion chamber via a direct injector positioned to inject directly into the combustion chamber, injecting a second, different, fuel to the combustion chamber via an exhaust port injector positioned to inject toward an exhaust valve of the combustion chamber, and combusting the first and second fuels together in the combustion chamber.

Additional approaches for the reduction of particulate emissions in gasoline engines using optimized port+direct injection are described. These embodiments include control of the amount of directly injected fuel so as to avoid a threshold increase in particulates due to piston wetting and reduction of cold start emissions by use of air preheating using variable valve timing.

The invention relates to a control device for an internal combustion engine that includes a turbocharger, and an actuator that changes a turbocharging pressure by regulating exhaust energy for use in drive of the turbocharger. When a target torque is increased during execution of a lean burn operation, the control device switches an operation mode of the internal combustion engine from the lean burn operation to a stoichiometric operation. When the operation mode switching is performed in a turbocharging state, the control device determines whether a target torque is within a range of a torque realizable under the lean air-fuel ratio. When the target torque is within the range, the control device operates the actuator so as to keep the turbocharging pressure at a magnitude equal to or larger than a magnitude at a time point at which the operation mode is switched.

Fuel in a fuel tank is supplied by a low-pressure pump to intake passage injectors mounted on an intake manifold via a low-pressure fuel supply pipe and a low-pressure fuel distribution pipe. A high-pressure pump is provided on the low-pressure fuel supply pipe. The pressure of the fuel is boosted by the high-pressure pump, and then is supplied to in-cylinder injectors via a high-pressure fuel distribution pipe. In an intake passage injection (MPI) mode, excitation of a solenoid is stopped and operation of an electromagnetic spill valve is stopped so as reduce vibration and noise caused by the seating of the electromagnetic spill valve in a valve seat.

An internal combustion engine system includes an internal combustion engine including an in-cylinder injection valve and a fuel pressure adjustment mechanism, and a control device that executes fuel injection control at a time of automatic restart of the internal combustion engine that is automatically stopped, by controlling the in-cylinder injection valve and the fuel pressure adjustment mechanism, in which the control device includes a first controller that executes the compression stroke injection a first number of times after an automatic restart request is made and control the pressure of the fuel to a predetermined value, and a second controller that executes the intake stroke injection a second number of times after the compression stroke injection is executed the first number of times and make the pressure of the fuel lower than the predetermined value.

A diagnostic device incorporates a processor and a memory and diagnoses a failure related to a fuel injection system for an engine whose air-fuel ratio of is feedback-controlled. The diagnostic device includes a calculation unit which calculates a corrected value of a fuel injection amount according to a difference between a target value and a measured value of the air-fuel ratio. The diagnostic device includes a setting unit which sets a mask period in which a failure diagnosis is suspended, according to the corrected value upon switchover of a fuel injection mode. The diagnostic device includes a diagnostic unit which does not carry out the diagnosis in the mask period and carries out the diagnosis outside the mask period.

The method for controlling the operation of an internal combustion engine comprises at least two operating modes. In a first operating mode, the intake valve is closed at a first predetermined crank angle, in accordance with the Miller cycle, before the piston reaches bottom dead center during the intake stroke for reducing pressure in the cylinder, and fuel is injected using first fuel injection means optimized for large amounts of fuel. In a second operating mode the intake valve is closed at a second predetermined crank angle, in accordance with conventional intake valve closing timing, after or slightly before the piston has passed bottom dead center, and fuel is injected using second fuel injection means optimized for small amounts of fuel. The invention also concerns an internal combustion engine.