An engine control system which controls ignition timing for, and fuel supply to, an engine by scanning a map by using as parameters a first item of data representing the number of revolutions of the engine and a second item of data representing engine load. The engine control system includes filter means for providing a third item of data by suppressing the rate of change of the second item of data. The third item of data is used in place of the second item of data for scanning the map only when the engine is in a predetermined range of operating conditions in which the rate of change of a manipulated variable of a throttle valve, the number of revolutions of the engine and the rate of change of the engine load are all less than respective predetermined values.