Combustion state control system of internal combustion engine

摘要

In a direct injection spark ignition engine which is operable in lean-burn operation modes including a pre-mixture combustion mode and a stratified combustion operation mode and a stoichiometric air/fuel ratio operation mode, which are different in the desired air/fuel ratio. The degradation of combustion state is detected through misfire detection and if it is determined to be degraded, the desired air/fuel ratio, the EGR flow rate and the ignition timing are changed when the engine is operated in the stratified combustion operation mode, while the desired air/fuel ratio, the EGR flow rate and the purge flow rate are changed when the engine is operated in the pre-mixture combustion operation mode, thereby ensuring to suppress the combustion state degradation effectively.