Ignition timing control system for internal combustion engines

摘要

A method and a system for controlling the ignition timing of internal combustion engines, or more in particular for preventing engine over-revolutions by reducing the engine speed when it becomes excessively high. The ignition timing control system is realized by a microcomputer, so that when the engine speed exceeds a predetermined high level, ignition stop operations by an ignition stop unit and ignition retard operations by a retarded ignition unit are repeated as many times as determined by the number of cylinders involved to reduce the engine speed. When the engine speed is in a predetermined high range, the ignition retardation is controlled by feedback in accordance with the engine speed, and further controlled in combination with the ignition stop as required. The method and system according to the invention is suitably used for a multi-cylinder internal combustion engine having an ignition system of electronic distribution type with a carburetor and a simultaneous ignition coil.