| 摘要 |
A combustion air-fuel ratio control system controls the combustion air-fuel ratio when the warming-up of the catalyst is required and achieves an increase in the catalyst temperature at an early stage. When warming up of the catalyst is requested it determines whether or not the exhaust air-fuel ratio sensors that detect the exhaust air-fuel ratio upstream the catalyst on the exhaust passage is active, and if the exhaust air-fuel ratio sensor is inactive, it sets the combustion air-fuel ratio to the primary combustion air-fuel ratio, which is between the theoretical ratio and the combustion limit air-fuel ratio, which is richer than the theoretical ratio and allows stable combustion using open control, and if the exhaust air-fuel sensor is active, it sets the combustion air-fuel ratio to the secondary combustion air-fuel ratio, which is richer than the primary combustion air-fuel ratio and near the combustion limit air-fuel ratio using feedback control.
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