Method of controlling intake air quantity for internal combustion engines

Abstract

A method of controlling the quantity of supplementary air being supplied to an internal combustion engine having first and second control valves arranged, respectively, in first and second auxiliary air passages bypassing the throttle valve for on-off control of the opening areas of the respective auxiliary air passages. When the engine is operating in a particular operating condition, the first and second control valves are selectively actuated in response to the detected value of atmospheric pressure encompassing the engine in such a manner that the sum of the opening areas of the first and second auxiliary air passages increases as the detected value of the atmospheric pressure decreases. The engine is determined to be operating in the particular operating condition when it is in a cranking condition, when a predetermined period of time has not yet elapsed after the engine has got out of a cranking condition, or when the engine is in a warming-up condition. Preferably, the engine includes a third control valve arranged in a third auxiliary air passage bypassing the throttle valve, and adapted to increase the opening area of the third auxiliary air passage with a decrease in the engine temperature for controlling the supplementary air quantity to be supplied to the engine through the third auxiliary air passage to an appropriate value when the engine is operating in a warming-up condition at a predetermined reference atmospheric pressure.