| 摘要 |
PURPOSE:To prevent a fuel-rich condition due to evaporated fuel and the fluctuation of an air-fuel ratio at the time of idling by opening widely an intake secondary air flow adjusting valve until complete engine combustion at a high temperature start and closing said valve gradually at the time of idling. CONSTITUTION:A control circuit 20 is connected with an intake absolute pressure sensor 10, a crank angle sensor 11, a cooling water temperature sensor 12, an O2 sensor 14, an atmospheric pressure sensor 17, an ignition switch 16 and a negative pressure switch 7 to be turned ON at the closing of a throttle valve 3, and controls an air-fuel ratio via a linear type electromagnetic valve 9 on an intake secondary air supply passage 8. When a start time at a high temperature has been detected on the basis of cooling water temperature, the electromagnetic valve 9 is wide opened during a stage of cranking to complete combustion. And the opening of said valve 9 is gradually reduced when an engine 5 has transited to idling.
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