Method and apparatus for controlling the air-fuel ratio in an internal combustion engine

摘要

The amount of fuel supplied to the engine is corrected in accordance with an air-fuel ratio correction coefficient. When the engine is in a predetermined first operating condition, the correction coefficient is calculated depending upon the detected concentration of a predetermined component in the exhaust gas, and thus the above correction is performed by closed-loop control. When the engine is not in the first operating condition, the correction coefficient is fixed, and thus the above correction is performed by open-loop control. An average value of the calculated correction coefficient is calculated only when the engine is in a predetermined second operating condition. An initial value of the air-fuel ratio correction coefficient when closed-loop control is resumed is determined to be the calculated average value.