| 摘要 |
PROBLEM TO BE SOLVED: To provide a diagnostic device capable of accurately performing misfire judgment even when the waveforms of misfire parameters are affected by disturbance and fluctuate. SOLUTION: The diagnostic device is provided with a means 7 which measures, at each cylinder, a time required for a predetermined crank angle interval corresponding to a combustion stroke based on a signal of a sensor 5 detecting the rotation position of a crankshaft, a means 7 storing the time measurement of each cylinder at every ignition, a means 7 calculating the first misfire parameter MISB from the stored values, a means 7 calculating the second misfire parameter from the stored values, a means 7 calculating the third misfire parameter which is a differential value of the first misfire parameter, a means 7 setting a judgment value by using a relational expression of the third misfire parameter MISC and the second misfire parameter MISA and a means 7 determining whether or not misfire is caused in the cylinder, based on the judgment value. COPYRIGHT: (C)2009,JPO&INPIT
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