Combustion control system for four cycle direct injection engine and the

Abstract

A combustion control system and method of a four cycle direct injection engine includes an igniter for igniting simultaneously in two cylinders, a firing cylinder and an off-firing cylinder. In the combustion control system, it is judged whether or not the spark discharge period following the ignition timing overlaps with the fuel injection period following the fuel injection starting timing. If it is judged not to overlap, the fuel injection starting timing determined based on the engine speed and the fuel injection amount is let be a final fuel injection starting timing. If it is judged to overlap, the spark discharge ending timing is obtained from the ignition timing and the spark discharge period and this spark discharge ending timing is let be a final fuel injection starting timing. By delaying the fuel injection starting timing until the final fuel injection starting timing, it is possible to prevent the off-firing cylinder from being fired when the igniter ignites simultaneously in the firing and off-firing cylinders.