Air/fuel ratio control device of a turbocharged engine

摘要

An engine including a supercharger wherein a waste gate valve is provided in the bypass passage bypassing the exhaust turbine of the supercharger and the supercharged pressure is controlled by the waste gate valve so that when the opening of the throttle valve provided in the intake duct falls under a set level, the air-fuel mixture is made lean and when it becomes greater than the set opening, the air-fuel mixture is made rich. When the air-fuel mixture is changed from a lean to rich mixture, the opening of the waste gate valve is made larger to reduce the supercharged pressure and thereby prevent abrupt fluctuations in the engine output.