Fuel supply control method for an internal combustion engine, adapted to

Abstract

A fuel supply control method for electronically controlling the air/fuel ratio supply to an engine, in response to the output from means for detecting concentration of an ingredient in exhaust gases from the engine. When the engine is in a feedback control region, the air/fuel ratio control is effected by the use of a first coefficient, the value of which is variable in response to the output from the exhaust gas ingredient concentration detecting means, while simultaneously a mean value of values of the first coefficient applied during the feedback control operation is calculated for use as a second coefficient. The second coefficient and a predetermined value are used for control of the air/fuel ratio, in place of the first coefficient, respectively, when the engine is in a first one of the particular operating regions and when the engine is in a second one of same. Preferably, when there is a transition of the operating condition of the engine from one of the particular operating regions to the feedback control region, the air/fuel ratio control is initiated by the use of a second predetermined value other than the above predetermined value, preferably the above second coefficient, in place of the first coefficient. Further, preferably, when the engine is in an idling region as the above second particular operating region, the air/fuel ratio is further corrected by a correction variable corresponding to a preset voltage supplied from a variable voltage creating means.