Ignition timing control system for internal combustion engine

Abstract

An ignition timing control system for an internal combustion chamber includes means for holding a maximum peak position signal of an indicative pressure signal at each engine cycle, means for picking up the held maximum peak position data signal, and means for establishing a suitable ignition angle for keeping the ignition timing to a target optimum ignition timing on the basis of the picked-up maximum peak position signal. The pick-up period is restricted within a narrow crank angle region in which any appreciable level of noises will not be expected in the indicative pressure signal. The narrow crank angle region is defined precisely by counting clock or timing pulses produced therein up to a predetermined number or by supervising the variation in level of the indicative pressure signal.