System for controlling idling rpm by synchronous control of supplementary air

摘要

A system adapted to control a control valve for controlling the quantity of supplementary air being supplied to an internal combustion engine, in a feedback manner responsive to a difference between actual engine rpm and desired engine rpm at engine idle. The above control valve is opened in synchronism with a signal indicative of a predetermined rotational position of the engine. The system is also adapted to detect a total quantity of suction air including the supplementary air being supplied to the engine, in synchronism with the above predetermined rotational position signal, to supply a quantity of fuel corresponding to the detected total suction air quantity. Further, the system is adapted to start opening the control valve upon a lapse of such a period of time after each pulse of the predetermined engine rotational position signal has been inputted to the system that a proper value of the total suction air quantity can be detected at the time of inputting of the next pulse of the same signal to the system.