Air-fuel ratio control system for engine

摘要

An air-fuel ratio control system for an engine for controlling an amount of a fuel mixture to be delivered into a combustion chamber so that an air-fuel ratio of the fuel mixture attains a target air-fuel ratio performs selecting one of a plurality of predetermined target air-fuel ratios according to engine operating conditions, controlling an amount of a fuel mixture so as to attain a selected target air-fuel ratio, and changing a speed at which the target air-fuel ratio is changed from one to another ratio higher with an increase in deviation of the other target air-fuel ratio from the one target air-fuel ratio.