Adaptive cylinder by cylinder knock retard control

A method for timing the ignition spark events of a spark ignited internal combustion engine in a manner to adaptively improve engine performance cylinder by cylinder comprising the steps of:

• detecting the crankshaft rotational position to determine the base timing for successive firings of each engine cylinder;
• adjusting the spark timing of each engine cylinder individually to improve cylinder performance sequentially, one cylinder at a time;
• detecting knocking of each of the individual engine cylinders;
• storing information describing the knock history of each individual cylinder in an electronic engine control assembly for modifying the timing of a spark applied to each engine cylinder in response to detection of knock associated with that cylinder;
• said step of adjusting the spark timing for each cylinder including determining if the vehicle engine cranksahft revolution rate (RPM) is within a predetermined range;
• determining if the engine cylinder next to fire knocked the last time it was fired and,
• determining the spark timing of the next to fire cylinder the last time it was fired;
• determining whether the spark timing is retarded to the maximum if the next to fire cylinder did knock the last time;
• retarding the timing of the next to fire cylinder if it is not retarded to the maximum and did knock last time and if the timing is retarded to the maximum then keeping the maximum retard for the next cylinder firing;
• comparing the number of firings of the next to fire cylinder without knocking to a predetermined number;
• keeping the timing for the spark for the next cylinder firing the same if the number of firings of the next to fire cylinder since the last knock is under the predetermined number;
• determining whether the timing has advanced to the maximum if the number of firings of the next to fire cylinder without knock exceeds the predetermined number;
• keeping the maximum advance for the next cylinder firing if the timing is advanced to the maximum and there have been no knocks in the predetermined number of firings of the next to fire cylinder;
• advancing the spark timing of the next cylinder firing if the timing is not advanced to the maximum and the number of firings of the next to fire cylinder without knock exceeds the predetermined number;
• and
• said steps of retarding and advancing the spark advance timing are being accomplished in predetermined increments.