Method of and system for purifying exhaust gas for vehicles

摘要

Exhaust gas temperature is raised after a cold engine start so as to rapidly activate a catalyst in an exhaust line by retarding an ignition timing at which an air-fuel mixture is fired in the engine to a point after top-dead-center during a certain time interval and promoting combustion of the air-fuel mixture, thereby accelerating the catalyst to attain its effective activation temperature after the cold engine start as quickly as possibly. <IMAGE>