Patent ID: 6799453
Filing Date: 2004-10-05
Classification: F02D,G01M

Abstract:
A system for detecting misfire occurred in an internal combustion engine having a plurality of cylinders and installed in a vehicle, comprising:an engine speed sensor that outputs a signal at every prescribed crank angle indicative of a speed of the engine; misfire detection means for detecting misfire occurred in individual cylinders of the engine based on the signal outputted by the engine speed sensor; a wheel speed sensor that outputs a signal indicating a rotation speed of a wheel of the vehicle; first fluctuation value calculation means for calculating a first fluctuation value of the wheel rotation speed based on the signal outputted by the wheel speed sensor through a first filter; second fluctuation value calculation means for calculating a second fluctuation value of the wheel rotation speed based on the signal outputted by the wheel speed sensor through a second filter; specific running condition discrimination means for calculating a parameter indicative of a degree of fluctuation of the wheel rotation speed based on the calculated first fluctuation value and second fluctuation value, and for discriminating whether the vehicle is under a specific running condition that affects the misfire detection of the misfire detection means based on the calculated parameter; and misfire detection disable means for disabling the misfire detection of the misfire detection means when the specific running condition discrimination means discriminates that the vehicle is under the specific running condition.