When switching the combustion mode from a stoichiometric mode to a homogeneous lean mode, a controller starts switching of the combustion mode after switching of the opening angle of a tumble control valve is started. When a target operating point of an internal combustion engine lies outside a predetermined operational region that is set in a range that excludes at least a low intake load factor region and includes at least a medium intake load factor and medium engine speed region, the controller sets the waiting time from the start of switching of the opening angle of the tumble control valve to the start of switching of the combustion mode to be longer than when the target operating point lies in the predetermined operational region.

Internal combustion engine has direct injection fuel injection valve and port injection fuel injection valve. A requested fuel injection amount is calculated according to an engine operation condition. When the requested fuel injection amount is in first operation region in which the minimum fuel injection amount of direct injection fuel injection valve is exceeded, a direct injection fuel injection valve fuel injection amount is adjusted based on the requested fuel injection amount and a fixed amount, while maintaining a port injection fuel injection valve fuel injection amount at the fixed amount. First operation region is at least a region in which the requested fuel injection amount exceeds the direct injection fuel injection valve minimum fuel injection amount. In first operation region, the port injection fuel injection valve fuel injection amount is fixed at the minimum fuel injection amount of port injection fuel injection valve.

An engine control device controls a cylinder direct fuel injection type spark ignition engine provided with a fuel injection valve configured to directly inject fuel into a cylinder and an ignition plug configured to perform spark ignition for a gas mixture inside the cylinder. The engine control device executes a catalyst warm-up operation for retarding an ignition timing, during a compression stroke of the fuel injection timing, in a case where it is necessary to warm up an exhaust gas purifying catalyst inserted into an exhaust passage. In addition, the engine control device increases a valve overlap period as a piston crown surface temperature increases during execution of the catalyst warm-up operation.

An engine controller controls a direct fuel-injection, spark ignition engine including a fuel injection valve configured to directly inject a fuel into a cylinder, and an ignition plug that spark-ignites a mixture in the cylinder. The engine controller is provided with an acceleration request sensor configured to detect an acceleration request of a driver, and when the acceleration request occurs and a top surface temperature of a piston in the cylinder is lower than a predetermined temperature, the engine controller retards an ignition timing so that a period of time until a flame after the ignition reaches the piston top surface is extended.

Methods and systems are provided for restarting an engine when a high pressure fuel pump is degraded. In response to an indication of high pressure fuel pump degradation, fuel may be injected during an intake stroke, rather than a compression stroke, for a selected number of combustion events since the engine restart. By shifting to an intake stroke injection, the engine may be started even when sufficient fuel rail pressures are not available.

An engine controller controls a direct fuel-injection engine including a fuel injection valve for directly injecting a fuel into a cylinder and a valve overlap period adjusting mechanism for adjusting a valve overlap period between an open period of an intake valve and an open period of an exhaust valve. The engine controller is provided with an acceleration request sensor for detecting an acceleration request of a driver, and when the acceleration request occurs and a top surface temperature of a piston in the cylinder is lower than a predetermined temperature, the engine controller extends the valve overlap period between the open period of the intake valve and the open period of the exhaust valve, ranging before and after an exhaust top dead center.

An engine control device controls a cylinder direct fuel injection type spark ignition engine provided with a fuel injection valve configured to directly inject fuel to a cylinder and an ignition plug configured to perform spark ignition for a gas mixture inside the cylinder. In a case where it is necessary to warm up an exhaust gas purifying catalyst disposed in an exhaust passage, the engine control device executes a catalyst warm-up operation in which a fuel is injected at a timing during the compression stroke, and at a timing when the fuel spray colliding with the piston crown surface moves toward the ignition plug along the shape of the piston crown surface, and in which the ignition timing is after compression top dead center. The engine control device advances the fuel injection timing in accordance with an increase in an estimation amount of a liquid fuel remaining on the top surface of the piston during execution of the catalyst warm-up operation.

An engine controller controls a direct fuel-injection engine including a fuel injection valve for directly injecting a fuel into a cylinder and a valve overlap period adjusting mechanism for adjusting a valve overlap period between an open period of an intake valve and an open period of an exhaust valve. The engine controller is provided with an acceleration request sensor for detecting an acceleration request of a driver, and when the acceleration request occurs and a top surface temperature of a piston in the cylinder is lower than a predetermined temperature, the engine controller extends the valve overlap period between the open period of the intake valve and the open period of the exhaust valve, ranging before and after an exhaust top dead center.

A target air amount for achieving a requested torque is back-calculated from the requested torque using a virtual air-fuel ratio. The virtual air-fuel ratio is changed from a first air-fuel ratio to a second air-fuel ratio in response to a condition for switching an operation mode being satisfied. After the virtual air-fuel ratio is changed, the target air-fuel ratio is maintained at the first air-fuel ratio until the ignition timing reaches a retardation limit. Subsequently, in response to the ignition timing reaching the retardation limit, the target air-fuel ratio is switched from the first air-fuel ratio to a third air-fuel ratio. After switching of the target air-fuel ratio, in response to a difference between the target air amount and an estimated air amount becoming equal to or less than a threshold value, the target air-fuel ratio is switched from the third air-fuel ratio to the second air-fuel ratio.

A control apparatus for an internal combustion engine having an air flow control valve which changes intake air flow achieves the stratified lean combustion, in place of the homogeneous lean combustion, in a specific combustion stroke of a specific cylinder, when it switches the opening of the air flow control valve, if all of or a part of a specific intake stroke overlaps with a switching period of the air flow control valve, the specific combustion stroke following the specific intake stroke of the specific cylinder. As a result, even when the opening of the air flow control valve is changed, it is possible to make combustion stable. Thereby, the occurrence of torque fluctuation is suppressed.