| 摘要 |
PROBLEM TO BE SOLVED: To provide a diagnostic device for an evaporated fuel processing system performing accurate leak diagnosis under stable conditions. SOLUTION: An ECU18 vacuum-seals the evaporated fuel processing system at a predetermined negative pressure by means of the control of valves 10, 11, 14, 17. The ECU 18 clocks the time td2 until the inner pressure Pte of the vacuum-sealed evaporated fuel processing system reaches a target inner pressure Pd, sets a pressure change measurement time te2 based on this clocked time td2, and measures the amount of pressure change P1 that the inner pressure Pte of the vacuum-sealed evaporated fuel processing system makes during the pressure change measurement time te2 after reaching the target inner pressure Pd. Then, a diagnosing part 25 sets a judging value Pth0 at least based on the space volume of the evaporated fuel processing system, determining that the evaporated fuel processing system is normal when the amount of pressure change P1 is greater than the judging value Pth0, and abnormal when the amount of pressure change P1 is smaller than the judging value Pth0. COPYRIGHT: (C)2006,JPO&NCIPI
|
