METHOD OF DETECTING MISFIRE BY UTILIZING VARIATION OF ROTATION OF CRANKSHAFT

摘要

A misfire detecting method capable of detecting the occurrence of misfire accurately without involving a misfire detection error ascribable to the vibratory increase and decrease, which occurs after misfire has happened, of the variation rate of rotation of a crankshaft, and, moreover, requiring no special hardware for this purpose. The angular accelerations D omega n-2, D omega n-1, D omega n and D omega n+1 in the crank angle regions corresponding to the preceding cylinder, two cylinders to be subjected to the detection of misfire and the succeding cylinder are calculated sequentially by a processor to which pulse outputs are inputted from a crank angle sensor. When the values D omega n-1 and D omega n decrease considerably as compared with values D omega n-2 and D omega n-1, a tentative judgement that misfire occurs in the two object cylinders to be detected is made. When the value D omega n+1 then increases appreciably as compared with the value D omega n, the restoration to normal combustion condition is ascertained, and the occurrence of misfire in these two object cylinders to be detected is definitely determined.