Patent ID: 6865880

Claim:
An exhaust control system for a cylinder fuel injection engine, comprising: cylinder injection injectors for directly injecting fuel into combustion chambers; a catalytic converter provided in an exhaust passage from said combustion chambers for purifying an exhaust gas; and a catalytic converter temperature measuring means for measuring a temperature of the catalytic converter for making an unfueled interval between two auxiliary injections longer when the temperature of the catalytic converter is lower than a predetermined value, wherein at least one time of auxiliary fuel injection is performed at a timing from expansion stroke to exhaust stroke after a primary injection in which a primary fuel is injected for obtaining an output of the engine, the primary fuel injection occurring before a timing of a spark ignition in a cylinder and the auxiliary fuel injection occurs in a cylinder in a predetermined period to increase concentration of carbon monoxide and hydrocarbon in the exhaust gas, and a cylinder having no auxiliary fuel injection is operated with lean mixture and supplied surplus oxygen to the exhaust gas.