To precisely learn a characteristic in a very low flow rate of an injector when a fuel injection amount is reduced as in a case such as an idling operation condition, in a spark-ignited direct injection engine operated in a stratified charge combustion state within a low load and low rotational speed area.
When the engine 1 after warming-up is idling-operated in a stratified charge combustion mode, an external load for the engine 1 is forcibly brought into an off-condition to fix a sucked air amount substantially constantly, and a fuel injection amount is controlled by rotation-feedback control to converge an engine speed ne to an idling speed. An ignition timing is retarded gradually from an MBT to learn actual dispersion of fuel induction in plural set ingition timings based on respective rotational speed feedback correction values cnefb to correspond to plural injection pulse widths Ti in a small range (a) of the pulse width Ti corresponding to the characteristic in the very low flow rate of the injector 12.
YAMAMOTO HIROYUKI
ARAKI KEIJI
