| 摘要 |
PURPOSE: A monitoring method of a fuel system of a vehicle is provided to improve reliability in fuel system monitoring by detecting the density of NOx. CONSTITUTION: A monitoring method of a fuel system comprises the steps of: calculating mileage(20); deciding if a fuel system monitoring condition is satisfied(21); outputting the difference between a theoretical air-fuel ratio and a measured air-fuel ratio and calculating an intake air flow rate(22); deciding if an air-fuel ratio difference absolute corresponds to a specific constant and the air-fuel ratio difference is over zero(23,24); calculating the densities of CO and NOx according to compensation factors, intake air amount, and air-fuel ratio and average density according to the mileage; and deciding an error if the average density is over a specific level. Therefore, a fuel system is reliably monitored.
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