Leak diagnosis system for evaporative emission control system

摘要

A leak diagnosis system is provided for diagnosing a leak condition of an evaporative emission control system for an internal combustion engine. The leak diagnosis system receives a signal indicative of a pressure in the evaporative emission system and obtains a converged limit negative pressure in the evaporative emission control system when the evaporative emission control system is communicated with the operating engine. The leak diagnosis system diagnoses a leak condition by comparing the converged limit negative pressure with a leak decision value.