Turbocharged engine purge flow monitor diagnostic

摘要

A method is provided for testing the evaporative emission system of a vehicle having a forced induction engine. The method includes controlling a vacuum bypass valve and a purge flow control valve to create the necessary conditions to perform the testing of the evaporative emission system. The method determines whether an evaporative system integrity monitor switch is open after a timer is initiated and the vacuum bypass valve is opened.

主权项

1. A diagnostic method for an integrity monitor switch of an evaporative emission control system for a fuel system in a vehicle powered by a forced induction engine, the vehicle including a vacuum bypass valve and at least one check valve preventing airflow from the engine back to the fuel system, the diagnostic method comprising:
in response to the forced induction engine turning off, initiating a timer and commanding, by a controller of the vehicle, the vacuum bypass valve to open; in response to commanding the vacuum bypass valve to open, determining whether the integrity monitor switch is open; when the integrity monitor switch is open, commanding, by the controller, the vacuum bypass to close; and when (i) the timer has expired and (ii) the integrity monitor switch is not open, detecting a malfunction of the integrity monitor switch.