Air/fuel ratio control system for internal combustion engines, having air/fuel control function at engine deceleration

摘要

An air/fuel ratio control system for feedback control of the air/fuel ratio of a mixture being supplied to an internal combustion engine is provided which comprises an absolute pressure sensor for detecting the absolute pressure in the intake pipe of the engine, and means operable to interrupt the air/fuel feedback control operation and immediately move an actuator for driving an air/fuel ratio control valve to a predetermined position and hold it there when the absolute pressure in the intake pipe, detected by the absolute pressure sensor is lower than a predetermined value at engine deceleration. This arrangement can ensure best driveability and best exhaust gas emission characteristics of the engine at engine deceleration.