| 摘要 |
<p>PURPOSE:To calculate a leakage area by using pressure values and times in decompression of a fuel component flow passage system reaching a purge passage via a canister from a fuel tank and in a recovery of the pressure after a stop of decompression as main parameters so as to precisely diagnose leakage from a dimension of the leakage area. CONSTITUTION:When an engine enters an operation area in which diagnosis can be carried, a drain cut valve 28 is closed while a bypass valve 32 and a purge cut valve 27 are opened, and in this way, an inlet negative pressure is introduced to a fuel component flow passage system 29 including an evaporative fuel passage 22 and a purge passage 24 via a collector 25. Then, a control unit 36 calculates a leakage area by using a pressure reduction valve and a pressure reduction time in decompression of the fuel component flow system 29 and a pressure increase value and a pressure increase time in a recovery of the pressure after a stop of decompression as main parameters, and it is determined whether it is in a normal condition or in an abnormal condition on the basis of a dimension of the leakage area.</p> |
