Idling rpm feedback control method for internal combustion engines

Abstract

An idling rpm feedback control method comprises controlling the quantity of supplementary air being supplied to an internal combustion engine equipped with at least one equipment which creates a load acting on the engine and includes at least one electrical device, in a feedback manner responsive to the difference between actual engine rpm and desired idling rpm during idling of the engine. The method also comprising varying the quantity of fuel being supplied to the engine in response to detected values of the total quantity of intake air inclusive of supplementary air at each predetermined rotational angle of the engine, so as to maintain the air-fuel ratio of a mixture being supplied to the engine at a desired value. When a transition is detected in the operative state of the load-creating equipment, the supplementary air quantity is varied by a predetermined amount corresponding to the magnitude of load of the load-creating equipment, and the fuel quantity is varied by a predetermined amount a predetermined number of times corresponding to the magnitude of the load-creating equipment. Preferably, the above variation of the fuel quantity is initiated after the lapse of a predetermined period of time from the start of the above variation of the supplementary air quantity.