Abstract: A control system for an internal combustion engine adjusts at least one predetermined control parameter such that a rate of combustion variation calculated based on a detected state of combustion of the engine becomes equal to a desired rate of combustion variation, which is dependent on operating conditions of the engine. A state of engagement of a lock-up clutch connected to the engine and a slip ratio of a torque converter connected to the same are detected. The desired rate of combustion variation is corrected in dependence on at least one of the detected state of engagement of the lock-up clutch and the detected slip ratio of the torque converter.

Abstract: A method of controlling an internal combustion engine having at least one intake valve comprises the steps of (1) detecting a demand of the driver to the engine, (2) detecting operating parameters of the engine including engine rotational speed, and (3) setting the timing of closing the at least one intake valve to timing which makes output of the engine the maximum at the detected engine rotational speed, when it is detected that the driver demands that the maximum output of the engine should be obtained in at least a predetermined operating region of the engine.