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      03-15-2012, 06:15 PM   #15
davesz4mc
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Drives: 2007 z4mc
Join Date: Feb 2012
Location: San Antonio, Tx

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Take the airbox to intake hose off and flex it your hands to look for cracks, That is what it sounds like to me.

When you first start it you hear it untill the vacuum pulls the cracks closed, then anything under load it opens/pulls air through the cracks? Just a thought.