| 摘要 |
PURPOSE:To improve the controllability of an air-fuel ratio by having an injection quantity controlled respectively on the basis of the opening of a throttle valve and the rotational speed of an engine when the opening of a sub control valve inside a sub suction air passage bypassing the throttle valve is below a predetermined value, and on the basis of a real suction air amount and the rotational speed of the engine when it is above the predetermined value. CONSTITUTION:At a main suction air passage provided with a throttle valve 8, a bypass 14 which functions as a sub suction air passage is connected so as to bypass the throttle valve 8, and an ISC valve (sub control valve) whose drive source is a pulse motor is provided on its way. And during the operation of an engine, whether the opening of the ISC valve 16 surpasses a predetermined value or not is decided at a control circuit 44, and when decided that it is below the predetermined value, a basis fuel injection time is operated on the basis of the output of a throttle valve opening sensor 10 and the rotational speed of tan engine sought at a rotational angle sensor 48. Meanwhile, when it has been decided that the opening of the ISC valve 16 surpasses the predetermined value, it is so arranged that the basic fuel injection time is operated on the basis of the output of a suction air pipe pressure sensor 6 and the rotational speed of the engine.
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