To operate an internal combustion engine so that a combustion state without output fluctuation and with stability is maintained in a cold condition, in a control system for an internal combustion engine comprising a variable valve system capable of varying operation timing of an intake valve.
The variable valve system is provided to vary valve closing timing of the intake valve. In a cold operation of the internal combustion engine (Step 100), if a misfire is detected (Step 110), a target compression ratio t is increased (Step 112), or if knocking is detected, the target compression ratio t is decreased (Step 114). Target valve closing timing tIVC of the intake valve for realizing the target compression ratio t is computed (Step 116). A maximum lift IVLMax and valve opening timing IVO of the intake valve are decided so as to bring an intake air quantity GN at a desired value while realizing the target valve closing timing tIVC (Step 120).
FUWA NAOHIDE
KANAMARU MASANOBU
WATANABE SATOSHI
KONISHI MASAAKI
