Patent ID: 6769419
Filing Date: 2004-08-03
Classification: B60K,B60W,F02M,Y02T

Abstract:
A diagnostic apparatus for an evaporated fuel system in which fuel vapor, evaporated from fuel within a fuel tank, is adsorbed, and the adsorbed fuel vapor is purged into an intake passage of an internal combustion engine via a purge passage by using a negative pressure of the intake passage, comprising:a malfunction determination unit determining whether a malfunction in the evaporated fuel system occurs, based on an internal pressure in the evaporated fuel system after the evaporated fuel system pressure reaches a reference pressure by introduction of the negative pressure of the intake passage into the fuel tank; and an upper-limit changing unit changing, when the malfunction determination unit performs the determination regarding the malfunction, an upper-limit value of an opening angle for a throttle valve to a second upper-limit value that is smaller than a first upper-limit value of the throttle valve opening angle used when the malfunction determination unit does not perform the determination.