Abnormal combustion detection apparatus and method for internal combustion engine

摘要

An abnormal combustion detection apparatus for an internal combustion engine quickly detects the occurrence of preignition by using a knock sensor. When the knock sensor detects an engine knocking, the ignition timing is delayed. If despite the delay of ignition timing, the knocking is not decreased and the air-fuel ratio detected after the delay of ignition timing is less than the air-fuel ratio detected before the delay of ignition timing, it is determined that preignition has occurred.