| 摘要 |
PURPOSE:To prevent drivability and emission from deteriorating, by providing a downstream side air-fuel ratio sensor, which detects air-fuel ratio of an internal combustion engine, and a correcting means which stops correction of an air-fuel ratio feedback control constant in the specific time. CONSTITUTION:An internal combustion engine provides in its exhaust passage a ternary catalyst CCRO, and a downstream side air-fuel ratio sensor, which detects air-fuel ratio of the engine, is provided in the exhaust passage in the downstream side of the ternary catalyst CCRO. A discriminating means discriminates the duration time CNT for whether or not it exceeds the predetermined time (n). In the point of the duration time exceeding the predetermined time, an air-fuel ratio control amount FAF is increased or decreased by the predetermined amount in a reverse direction to the direction the control amount is increased or decreased during the duration time. In this way, emission can be prevented from deteriorating by preventing an air-fuel ratio overcorrected condition before its occurrence.
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