2005 MY OBD System Operation Summary for Gasoline Engines

1#4;!In this phase, the EONV test is considered complete for this key-off cycle. The resultant peak pressure and peakvacuum are stored along with total test time and other information. This information is sent to the mainmicroprocessor via CAN at the next engine start. During this phase, the CVS is commanded open and theelectrical components performing the EONV test are shutdown to prevent any further power consumption.;0+During the EONV test, several parameters are monitored to abort the EONV test under certain conditions. Theprimary abort conditions are instantaneous changes in tank pressure and fuel level. They are used to detectrefuel events and rapidly open the CVS upon detection of them. A list of abort conditions is given below.::Test results are transferred to the main microprocessor upon detection where they are processed todetermine if MIL illumination should occur. Because of the inherent variability in vapor temperaturechanges and fuel volatility, results from multiple EONV runs are normalized and averaged todetermine if a malfunction should be set. An average of four key-off EONV runs are used to determinea malfunction. If two malfunctions are set in a row, the MIL will be illuminated. Using this approach, atotal of eight, key-off EONV runs will be required to illuminate the MIL.FORD MOTOR COMPANY REVISION DATE: APRIL 28, 2004 PAGE 30 OF 131