| 摘要 |
PURPOSE:To effectively protect a catalyst from being overheated by stopping feedback control and setting a fuel injection time longer than the minimum injection time in the case where an output signal of an oxygen concentration detector is continued at a set voltage or less for a preset time when decelerating operation is performed. CONSTITUTION:An electronic control unit 30 determines during operation of an engine, if output voltage V of an oxygen concentration detector 20 is set voltage V1 or less, in the case when it is detected that the state of engine operation is transferred in a decelerating operation condition. And an counter is operated in the case when output voltage V is less than set voltage V1 a lean flag is set (i) after a preset time passes, feedback correction factor is set at 1 and feed back control is stopped. Accordingly, fuel injection time longer than a predetermined minimum injection time, an air-fuel mizture is made richer, and unburnt gas is prevented from being exhausted while preventing a catalyst from being overheated. Accordingly, the flag is reset in the case where output voltage V is higher than set voltage V1.
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