| 摘要 |
PURPOSE:To prevent an air-fuel ratio from getting out of position due to a change in an exhaust gas sensor with aging, by changing a reference value in accordance with a ratio between periods of time until the exhaust gas sensor reaches the reference value from a maximum value on a rich side and it reaches the reference value from a minimum value on a lean side in air-fuel ratio feedback control. CONSTITUTION:An electronic control unit 5 calculates a basic amount of fuel injection based on values sensed by a suction gas absolute pressure sensor 8 and an r.p.m. sensor 10 and compares a value sensed by an O2 sensor 13 with a reference value for effecting feedback control of an air-fuel ratio by proportional integral control. The electronic control unit 5 compares an average shift time during which an output sensed by the O2 sensor 13 shifts from a maximum value on a rich side to the reference value with an average shift time during which it shifts from a minimum value on a lean side to the reference value for sensing a deviation of the air-fuel ratio and corrects the reference value so that the deviation is reduced.
|
