PURPOSE: To accelerate countermeasure for abnormality of a cylinder pressure detecting means, by sampling the detected result of the cylinder pressure at a plurality of crank angle position, and judging the abnormality of the cylinder pressure detecting means based on the sampled result.
CONSTITUTION: A charge signal corresponding to a cylinder pressure from a cylinder pressure sensor 21 is converted into a voltage signal S4 by a charge amplifier 31. Sampling parts 37D and 37E receive a reference signal S2 and a position signal S3 from a crank angle sensor 13 and sample the detected signal S4 at a specified crank angle and at a compression top dead center (TDC) in a suction stroke. Thus the abnormality of a cylinder pressure detecting means comprising the sensor 21 and the amplifier 31 is judged by an abnormality juding part 37F. The judged result is sent to a judgement-correcting-amount determining part 37B. The normalized value of the correlation value of combustion vibration from a ratio computing part 37A is corrected. The result is sent to an ignition time control part 37C.
NAKAJIMA YUUJI
ANPO TOSHIMI
NAITOU HIROYUKI
