Thread: No boost?
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      11-23-2012, 09:50 PM   #2
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Drives: E90 335i & C6 Grand Sport
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The vacuum pump is what supplies the vacuum needed to operate the wastegate actuators. If the pump isn't putting out what it should (25-30 in. hg), then the wategates might not close as they should.

I've personally never seen an N54 vacuum pump fail, but I guess anything is possible. Testing the vacuum control system is very easy if you know how the system works and what readings to look for.