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Old 11-07-2012, 11:42 AM   #27
SeanC
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Join Date: May 2007
Location: TX
Posts: 4,093
My Ride: 330i
There is a "one-way" mechanical valve that connects the SAP hose to the intake manifold in the back of the engine. Since it is a mechanical valve (opens when you blow air to it, etc.), It will momentarily open under driving conditions and cause a lean condition. Ideally it should only lean out when SAP is running (when the valve is open).
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