Method and apparatus for controlling ignition timing in an internal

Abstract

Engine parameters are detected to set a basic ignition timing, and this basic ignition timing is forcibly changed to effect feedback control in which engine output is detected for finding an optimum ignition timing. Engine is operated with a plurality of different ignition timings, where the number of the ignition timings is at least two, and engine output data for each ignition timing is measured to find which ignition timing causes a higher engine output. Thus, one of the plurality of ignition timings, which gives the lowest engine speed is replaced with a new ignition timing with which the engine produces higher output. The new ignition timing is computed in such a manner that the new ignition timing is located at a point opposite to the ignition timing giving the lowest engine output with respect to an average ignition timing, while the difference between the average value and the new ignition timing equals a multiple of the difference between the ignition timing giving the lowest engine speed and the average value. In this way the ignition timing is renewed successively for finding the optimum ignition timing.