METHOD AND SYSTEM FOR OPERATING AN ENGINE AT MAXIMUM TORQUE WITH VARIABLE AMOUNT OF DITHER

Spark ignition timing of an internal combustion engine is oscillated on each side of a variable reference setting during successive ignition phases and the resultant engine speed is detected during at least three successive phases. The detected engine speed values are compared one against each other to determine whether they satisfy one of two specified conditions. The variable reference is adjusted in a direction toward an optimum position depending on which one of the conditions is satisfied. At least one of controlled parameters including the magnitude of the oscillated setting with respect to the variable reference, the length of the ignition phase and the amount of the adjusted reference setting, is varied as a function of an engine operating parameter.