Unisia Jecs Corporation

Yutaka Kanbara

Akira Uchikawa

The present invention relates to an apparatus for diagnosing misfire of an internal combustion engine. With this invention, crank angle intervals for detecting angular velocity for each cylinder are variably set for each operation region. An average value of a predetermined number of misfire judgment values M1 set based on a plurality of angular velocities is compared with a reference value, to thereby carry out misfire diagnosis distinguishably of a misfire in a single cylinder or misfires in multiple cylinders.

Misfire diagnosis method and apparatus of internal combustion engine

A misfire diagnostic system for an Internal combustion engine comprises a crank-shaft angle sensor for monitoring a crankshaft angular velocity reflecting a combusting condition of each of engine cylinders, and a control unit for calculating an angular-velocity correction factor of each of the engine cylinders on the basis of the angular velocity in every engine operating region only under a stable engine operating condition. The control unit corrects the angular velocity by the angular-velocity correction factor of each of the engine cylinders for every engine operating region. The presence of a misfire is accurately decided on the basis of the angular velocity corrected for every engine cylinder and for every engine operating region.

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Atsugi, Japan

Yutaka Kanbara