This paper presents a technique for the improvement of the idle stability on a spark ignition engine through the adaptive control of the individual cylinder ignition timing. In many causes that affect the idle stability, the difference in the torque production between cylinders has been a matter of concern. The engine speed has been sampled 220 times per a cycle and the average angular acceleration has been calculated from it. In this research, the average angular acceleration has been characterized by nonuniform torque production among cylinders. The control system has been designed to keep the average angular acceleration constant.