Test Group VBM1.9VJGFEK

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General Description - Purge flow from charcoal canister through purge valve is monitored after fuel system adaptation is completed and lambda controller is at closed loop condition. Diagnosis is started during regular purging. See Fig 1.

For Rich Or Lean Mixture - Flow through purge valve is assumed as soon as lambda controller is compensating for a rich or a lean shift. After this procedure, diagnosis is completed and evaporative purge system resumes working normally.

For A Stoichiometric Mixture - In this case, lambda controller does not need to compensate for a deviation. Therefore, after finishing regular purging, purge valve is opened and closed abruptly several times. Effect of additional cylinder charge triggers by a variation of the engine idle speed. A predetermined value is reached if system functions properly and diagnosis procedure is completed.

Fig 1: Monitoring Structure Of Evaporative Purge System (Test Group VBM1.9VJGFEK, VBM4.4JGKEK & VBM5.4V8GFEK)

Courtesy of BMW OF NORTH AMERICA, INC.