| 摘要 |
A pressure correction method for leak diagnosis of a vehicle fuel tank is provided to form negative pressure in a desired pressure value by controlling opening amount of PCSV so as to allow a present pressure value to be reached to a target pressure value, and to reduce a unit cost by additionally needing no ORV. A pressure correction method for leak diagnosis of a vehicle fuel tank comprises the steps of checking conditions for starting the leak diagnosis of a fuel tank and judging if the conditions are satisfied, checking initial conditions before diagnosis start and judging if the all initial conditions are satisfied, opening PCSV, reducing pressure inside a tank and judging if variation width of a pressure slope is converged by calculating the pressure slope, judging if the pressure inside the tank is less than a standard value, calculating difference of present pressure and target pressure inside the tank and controlling opening amount of the PCSV according to difference of fuel amount and pressure, judging if the present pressure is reached to the target pressure, judging if the present pressure is larger than allowable pressure when the present pressure and the target pressure are same, and performing pressure calculation for the leak diagnosis when the present pressure is larger than allowable pressure.
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