Control system and method for an internal combustion engine with variable compression ratio

A control system for an internal combustion engine is provided. The engine includes a compression ratio control mechanism (102) and an ignition timing control system (103). The control system comprises an engine control (33) for controlling the compression ratio control mechanism (102) and the ignition timing control system (103) so that the compression ratio is varied depending upon variations of engine rpm, engine load and a warm-up condition of the engine and that when the engine is cold, the ignition timing is retarded from a MBT point and a top dead center position of a piston is made lower in level than that obtained when the engine is hot and operated at corresponding engine rpm and engine load. A method for controlling such an internal combustion engine is also provided.