| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve detection reliability of ignition plug abnormality and misfire detection system failure without requiring complicated adaptation confirming work. Ž<P>SOLUTION: A misfire diagnostic device is lighted on by setting a misfire state flag MNG ON when a state where misfire occurrence frequency is higher than a determination threshold value continues a prescribed number of times by calculating the misfire occurrence frequency by detecting misfire based on an ion electric current peak value within a misfire detection section when an engine control system is in a normal state, and thereafter, a normal combustion return flag MOK is set ON by determining that it returns to a normal combustion state when a state where the misfire occurrence frequency is lower than the determination threshold value continues a prescribed number of times. Ignition plug abnormality determination processing and misfire detection system failure determination processing is prohibited while the normal combustion return flag MOK is set ON after it returns to the normal combustion state from a misfire diagnosis state (misfire state flag MNG=ON). Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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