| 摘要 |
PURPOSE:To improve fuel consumption during constant running, by gradually approaching air-fuel ratio to a target air-fuel ratio which is leaner than a theoretical air-fuel ratio when engine load is in a predetermined range and an amount of change in the engine load becomes less than a predetermined value. CONSTITUTION:A control circuit 30 includes a ROM for receiving an output from various sensors for operating condition such as an air flow meter 2 and an engine speed sensor 28, and previously storing a target air-fuel ratio leaner than a theoretical air-fuel ratio according to an engine operating condition, e.g., an amount of suction air per one rotation of engine, that is, a load Q/N. Further, there is provided means for deciding whether or not the load Q/N is in a predetermined range and simultaneously an amount of change in the load DELTAQ/N is less than a predetermined value. Then, on the basis of the result of the decision, an injection time is corrected so that the air-fuel ratio may be gradually approached to the target air-fuel ratio every predetermined period of time, and ignition timing is corrected so as to be gradually approached to a required ignition timing corresponding to the target air-fuel ratio every predetermined period of time.
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