| 摘要 |
PROBLEM TO BE SOLVED: To avoid such a wrong diagnosis that the temporal disorder of the air-fuel ratio caused by the purge of vaporized fuel gas is regarded as an abnormality in a fuel system. SOLUTION: When the conditions to execute diagnosis are satisfied after the count value of an warming counter exceeds a specified value (after the finish of engine warming), primary diagnosis is carried out for preliminary diagnosing the presence and absence of abnormality in the fuel system (Steps 101 to 108). In the primary diagnosis, the time period for which a learning correction factor remains out of a specified range is integrated by a primary diagnosis abnormality counter, and if the integrated value exceeds, it is diagnosed that there is an abnormality in the primary diagnosis, and then secondary diagnosis is carried out. In the secondary diagnosis, the time period for which the total value of a learning correction value, that is, the abnormality diagnosis parameter in the secondary diagnosis, and a feedback correction factor remains out of a specified range is integrated by a secondary diagnosis abnormality counter, and if the integrated value exceeds a specified value, it is diagnosed that there is abnormality also in the secondary diagnosis, and such diagnosis that there is abnormality is decided finally.
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