| 摘要 |
An air-fuel ratio feedback control system for an automotive internal combustion engine equipped with an evaporative emission control device having an activated charcoal cansiter for absorbing fuel vapor from a fuel tank. The air-fuel ratio feedback control system is operated as follows: The air-fuel ratio of air-fuel mixture to be inducted into the engine is detected in accordance with a component of exhaust gas discharged from the engine. An air-fuel ratio feedback correction coefficient is set in accordance with the air-fuel ratio in such a manner as to be modified by a feedback control constant in response to the state of the air-fuel ratio relative to stoichiomeric value. The amount of fuel to be supplied to the engine is corrected with the air-fuel ratio feedback correction coefficient. Additionally, the feedback control constant is enlarged for a predetermined time when the evaporative emission control device is so operated that the fuel vapor stored in the activated charcoal canister is sucked into the engine, thereby improving follow-up ability of air-fuel ratio feedback control thus to improve exhaust emission control and driveability of the engine.
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