Monitoring Structure

Monitoring Structure







Monitoring Cycle of Evaporative Emission Canister Purge System Flow Check

Step 1 - For rich or lean mixture
Flow through the EVAP canister purge valve is assumed as soon as the lambda controller is compensating for a rich or a lean shift.

After this procedure the diagnosis is completed and the EVAP canister purge system resumes working normally.

Step 2 - For a stoichiometric mixture
In this case the lambda controller does not need to compensate for a deviation. Therefore, after finishing the regular purging, the EVAP canister purge valve is opened and closed abruptly several times.

The effect of additional cylinder charge will trigger a variation of the engine idle speed.
A predetermined value is reached if the system functions properly and the diagnosis procedure is completed.

To start the diagnosis function (step 2) several conditions have to be satisfied.
- vehicle speed = 0
- engine at idle speed
- closed loop of lambda controller
- engine coolant temperature > fixed limit
- transfer gears in high range

Furthermore if the diagnosis has already been started and one of the conditions has not been satisfied continuously, the process will be interrupted and started again later.
- engine idle speed variation < fixed limit