| 摘要 |
PURPOSE:To converge an air-fuel ratio fluctuation quickly by setting a proportional or integral constant at a high level for an air-fuel ratio feedback control system on an O2 sensor when fuel vapors are purged from a canister to an intake pipe. CONSTITUTION:A throttle body 5 is so made as to be able to purge a fuel tank 7 of fuel vapors via a canister 6 and a diaphragm type valve 8 opening and closing through the control of a solenoid valve 9 is provided in the canister 6. A control unit 10 for controlling the opening time of a fuel injection valve 4 on the basis of a suction air volume known from an air flow meter 14, the number of engine revolutions and a value detected by an O2 sensor, works to enlarge at least one of a proportional constant and an integral constant for an air-fuel ratio control system, depending upon output from the solenoid coil 9e of a solenoid valve 9 for purge control, and converges an air-fuel ratio fluctuation due to purging in good response.
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