To improve the precision of a misfire detection by reducing the incorrect detection of a half misfire in a misfire detector of an internal combustion engine.
There is set a half misfire estimated reference value K2, which is smaller than a misfire judgement reference value K1. Based on the frequency of an angular speed variation in a range between the misfire judgement reference value K1 and the half misfire estimated reference value K2, it is judged whether the misfire of the internal combustion engine decided on the frequency exceeding the misfire judgement reference value K1 is right or wrong in consideration that the angular speed variation results from the half misfire out of the frequency exceeding the misfire judgement reference value K1.
TSUKAMOTO KEISUKE
KUSANO HIROKI
TOYOTA IND CORP
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