Patent ID: 6658346
Filing Date: 2003-12-02
Classification: F02D,G01M

Abstract:
A misfire detection apparatus for an internal combustion engine comprising:rotational angle signal output means for outputting a rotational angle signal at a predetermined rotational angle in accordance with rotation of an output shaft of a multiple cylinder internal combustion engine; rotational speed calculation means for calculating a rotational speed of the output shaft of the internal combustion engine in each cylinder based on the rotational angle signal outputted from the rotational angle signal output means; first variation amount calculation means for calculating a rotational speed between two cylinders where expansion strokes are successively made, said first variation calculating means calculating by using the rotational speed calculation means and calculating a first variation amount based on the rotational speed between the two cylinders; second variation amount calculation means for calculating the rotational speed between two cylinders of the internal combustion engine by using the rotational speed calculation means, said second variation calculating means calculating a second variation amount based on a rotational speed between the two cylinders; first misfire determination means for performing misfire determination based on the first variation amount and the second variation amount; and second misfire determination means for performing misfire determination based on the first variation amount; whereby the second misfire determination means performs misfire determination during engine running when a possibility of erroneous misfire detection due to the second variation amount exists.