| 摘要 |
PROBLEM TO BE SOLVED: To improve accuracy of misfire detection as well as to recognize a misfire detection period at a constant interval at all times. SOLUTION: A crank angle sensor 25 outputs a reference position signal corresponding to a predetermined reference position of a crankshaft 18. A ring gear angle sensor 26 outputs ring gear signals corresponding to passage of teeth of a ring gear 24. A microcomputer 33 in an ECU 30 measures time when the reference position signal is input and time when the ring gear signals are input. If an interval between the input time of the reference position signal and that of the ring gear signals is shorter than a predetermined time determined based on operation load and processing speed of a computer and a peripheral circuit thereof, association between the ring gear signal and a crank angle is prohibited. If the interval is longer than a predetermined time, the association between the ring gear signal and the crank angle is permitted. Further, the microcomputer 33 detects misfire of an engine 10 based on a fluctuation amount of revolution speed of the engine 10 in a misfire detection period.
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