Apparatus for determining abnormal combustion in internal combustion engine

Abstract

An object is to provide an abnormal combustion determining apparatus for an internal combustion engine that can identify a major factor causing an oil to flow into a cylinder. The abnormal combustion determining apparatus for the internal combustion engine that includes a plurality of cylinders detects, for each cylinder, a cylinder in which abnormal combustion has occurred. The cylinder in which the abnormal combustion has occurred, and a history of load applied during an operation are stored in memory. It is determined whether or not the cylinder in which the abnormal combustion has occurred and which is stored in memory, is a specific cylinder. It is determined whether or not load present in the history stored in memory and used prior to the occurrence of the abnormal combustion is higher than a threshold value. Based on a combination of a decision made by the cylinder determining means and a decision made by the load determining means, a major factor causing the oil to flow into the cylinder is identified from among relations established for factors of oil flowing into the cylinder according to the combination of these decisions made.