Air-fuel ratio control system for internal combustion engines

摘要

An air-fuel ratio control system for an internal combustion engine, which detects the actual air-fuel ratio of a mixture supplied to the engine, detects operating conditions of the engine, calculates a desired air-fuel ratio based on the detected operating conditions of the engine, and calculates an air-fuel ratio correction value applied for feedback-controlling the actual air-fuel ratio to the calculated desired air-fuel ratio. A change rate at which the air-fuel ratio correction value is to be changed, is set such that when a change has occurred in the operating mode of the engine, the change rate is set to and held at a smaller value than a value assumed when no change has occurred in the operating mode, over a predetermined time period from the time the change occurred.