PURPOSE:To prevent an engine from being driven recklessly at the time of interruption of a traffic signal by a method wherein an air flow rate control section adopted to switch the flow rate of air depending on whether the engine is in a cooled condition or in a heated condition is provided in series with an air flow rate control valve which is arranged in a passage bypassing a throttle valve and which opens when the control signal is OFF. CONSTITUTION:An air intake pipe 11 is provided with the bypass passage 16 bypassing the throttle valve 15 and communicating with a surge tank 12. The bypass passage 16 is provided with the air flow rate control valve 18 which opens when the control signal is OFF and feeds back the number of revolutions of the engine. Further, the bypass passage 16 is also provided with the flow rate control section 17 which is arranged in series with the valve 18 and adopted to switch the flow rate of air in two stages in response to the cooled and heated condition of the engine. Accordingly, even when the air flow rate control valve 18 is kept open due to an accident, the quantity of air is regulated by the flow rate control section 17 when the engine is in a heated condition, to thereby prevent the creeping of a torque converter wheel.
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