| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent wrong diagnosis in abnormality diagnosis when fuel having a different alcohol concentration is supplied in an internal combustion engine in which an alcohol-mixed fuel can be used. Ž<P>SOLUTION: An alcohol concentration estimated at previous driving is stored in a backup RAM 39 of an ECU 38. Subsequently, engine control and abnormality diagnosis are performed using provisionally the stored value of the alcohol concentration estimated at the previous driving as an alcohol concentration at the current driving until driving conditions under which the alcohol concentration of fuel can be estimated is obtained after engine start. Then, at a time point when the alcohol concentration at the current driving estimated after the engine start is compared with the alcohol concentration at the previous driving stored in the backup RAM 39, thereby determining that the both are different from each other, processing data (for example, normal/abnormal determination results, data during abnormality diagnosis processing, and learning data) for abnormality diagnosis performed from the engine start to the time point is invalidated. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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