Abstract: A fuel supply control arrangement for use in an internal combustion engine, which is so adapted that, in the arrangement to decrease the air/fuel ratio, i.e., to enrich the air/fuel mixture at a specific operating region by increasing the amount of fuel supply, upon transfer into the specific operating region, the fuel is once increased to an amount more than a regular fuel amount for obtaining an air/fuel ratio set in the specific operating region, so as to be restored thereafter to the regular fuel amount, whereby undesirable leaning of the air/fuel mixture at an early stage of transfer into the specific operating state, arising from adhesion of fuel onto an intake passage wall surface can be prevented.

Abstract: The difference between the actual idling speed of an internal combustion engine and a desired idling speed determined according to the operating conditions of the engine is integrated and the opening angle of the throttle valve is controlled according to the integrated value to control the amount of the intake air, whereby the actual idling speed is equalized to the desired idling speed. When the actual idling speed becomes higher than a predetermined value, the idling speed control is interrupted with said integrating operation being continued and the throttle valve is positively closed.