Method for controlling ignition timing of an internal combustion engine

Abstract

An ignition controlling system has a memory storing a plurality of basic ignition timings each of which is a maximum timing for producing maximum torque with low-octane gasoline without causing knocking, and storing a plurality of maximum advance quantities. A learning control system has a memory storing a plurality of learning correcting quantities and rewriting the learning correcting quantity in accordance with occurrence of knocking of the engine. A basic ignition timing, a maximum advance quantity and a learning correcting quantity are derived from the memories in accordance with engine operating conditions. The learning correcting quantity is compared with the maximum advance quantity and smaller one is selected. The smaller quantity is added to the basic ignition timing to obtain an ignition timing.