| 摘要 |
PROBLEM TO BE SOLVED: To improve diagnostic reliability by detecting more appropriately fluctuation in internal pressure of an evaporation route when diagnosing failure of an evaporative purge system. SOLUTION: An evaporative purge system 20 is equipped with evaporation routes 30, 40, 71, 72 and so on for purging fuel vapor generated from a fuel tank 30 to the intake passage 12 of an engine 10. When failure based on secular change in internal pressure of the evaporation routes is diagnosed, an ECU 50 detects fluctuation in internal pressure of the evaporation routes under both conditions that difference in two values sampled by a different sampling mode in the detected results by a pressure sensor 32 is at a fixed value or more and the changing degree of the changing speed of the detected results by the pressure sensor 32 is at the fixed value or more, and prohibits execution of failure diagnosis when the detected frequency is at the fixed value or more.
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