Air/fuel ratio control system for internal combustion engine with correction coefficient learning feature

摘要

An air/fuel ratio control system detects transition of air/fuel ratio changing between rich and lean for checking if updating condition is satisfied. Updating value is derived based on a feedback correction value which is derived for adjusting air/fuel ratio toward a stoichiomentric value. With the updating value thus derived, one of a plurality of learnt correction value which are set with respect to various engine driving range.