Air-fuel ratio feedback control system for internal combustion engines, capable of achieving proper air-fuel ratios from the start of the engine

摘要

An air-fuel ratio feedback control system for use with an internal combustion engine, which is adapted to control the air-fuel ratio of a mixture being supplied to the engine, by the use of a first coefficient variable in response to the output of an exhaust gas concentration sensor arranged in the exhaust system of the engine when the engine is operating in an operating condition other than particular operating conditions, and by the use of a second coefficient which is a mean value of values of the first coefficient obtained during the above operating condition other than the particular operating conditions when the engine is operating in one of the particular operating conditions, for replacing the first coefficient with the second coefficient. Storage means is provided for storing and holding the value of the second coefficient even when the engine is inoperative.