Apparatus and method of combustion diagnosis/control in internal combustion engine

Abstract

An apparatus diagnoses and controls combustion of an internal combustion engine which makes smooth operation of an engine possible by adjusting the combustion condition at the occurrence of knock, misfire, and flame quenching and also makes it possible to detect the occurrence of abnormality in cylinder pressure detectors without delay and deal with the abnormality without stopping the operation of the engine. A maximum pressure ratio P /P is calculated, P being the maximum cylinder pressure and P being the compression pressure at one or a plurality of crank angles in the compression stroke P /P is compared with pressure ratios for each diagnosis category, the combustion conditions are diagnosed by judging the result of the comparison every cycle or plural cycles.