Method for reducing knocking in internal combustion engine

An anti-knocking control method for an internal combustion engine, comprising the steps of:

• detecting knocking of the engine;
• detecting a load condition of the engine;
• detecting an engine rotational speed;
• storing, at addresses of memory means corresponding to predetermined engine operating modes each defined by a load condition and speed of the engine, reference values calculated in accordance with detected knocking levels for operating modes of the engine corresponding to said addresses;
• reading out one of said reference values, stored at on of said addresses corresponding to a combination of a detected load condition and engine speed;
• calculating a correcting control value of at least one control parameter of the engine on the basis of said one read-out reference value and said detected knocking level to control knocking of the engine;
• determining whether a plurality of preconditions have been satisfied for a predetermined period of a number of ignitions of the engine;
• changing, after said predetermined period of the preconditions are satisfied, said control value to a new value in a knocking restricting direction when knocking is present and in an opposite direction when no knocking is present;
• and
• storing, at addresses of said memory means corresponding to said predetermined operating modes, said new control value.