| 摘要 |
An engine control apparatus and method can prevent engine stall in a reliable manner when the engine is changed from a high-speed loaded operation into an idling operation. An air/fuel mixture is supplied to engine cylinders 16 through an intake passage 1 with a throttle valve 6 disposed therein, and a bypass passage 10 with an air valve 12 disposed therein is connected with the intake passage 1 for bypassing the throttle valve 6 to supply auxiliary air to the cylinders. Based on an operating condition signal D in the form of an idle switch on/off signal, an electronic control unit (ECU) 30A detects a change from a loaded operation into an idling operation of the engine, and determines, based on a speed signal R from a speed sensor, whether the number of revolutions per minute of the engine R is equal to or less than a predetermined reference value Rk. The ECU 30A gradually closes the air valve 12 in the bypass passage 10 to decrease an amount of auxiliary air Ac flowing therein in a delayed manner when the engine is changed from a loaded operation into an idling operation, i.e., when the number of revolutions per minute of the engine becomes equal to or less than the predetermined reference value Rk.
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