| 摘要 |
PURPOSE:To compensate hourly variations of an O2-sensor by detect in the hourly variations of an engine based on the opening of an idle control valve for feedback- controlling the idling engine speed and changing an air fuel ratio feedback control constant on the rich side when the opening is above a specified value. CONSTITUTION:An air flow meter 17, an O2-sensor 24, a water temperature sensor 26, and engine speed sensor 29, an altitude sensor 38, and an air-conditioning switch 39 are connected to an electronic control unit 30 which calculates the fuel injection quantity, and controls an idle control valve 20 installed in a bypass-passage 19 through a step motor 21 so as to obtain the desired engine speed during idle running. Then, the electronic control unit judges that a vehicle runs on a flat ground, warming up is completed, and the engine is under idling condition with no-load, and then discirminates whether or not the number of steps of the step motor 21 for driving the idle control valve 20 is more than that specified. When the number of steps in more than that specified, the electronic control unit changes an air fuel ratio feedback control constant to be on the rich side assuming that the hourly variations are not completed.
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