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      04-15-2012, 12:18 PM   #4
Three_thirty_I
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Drives: '05 E90 330i Manual
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Found this on another forum, relating to 530i also using the N52 engines:

Could this be a DISA valve issue?

Quote:
Not sure which car you have-if its a 530, specifically the N52 engine and even the m54 engine--I have had, and many reports of it, are the DISA valves in the intake manifold that control which air path is open depending on which RPM band you are in--can come loose and rattle around while accerlating (since that is when they open) but when you stop accelerating they close and produce no rattle.

This took 5 times toa dealer to finally diagnosis.

It was not so much a "rattle" but a "whurring" kinda sound that was subtle but if you heard it then you could not forget it.

The check is to remove the intake manifold and inspect

THe thing is if this is missed and parts come loose inside the manifold-they get sucked into the engine and its good bye engine.

The only reason they found mine is I asked to have my spark plugs changed and they inspected the manifold as part of the service and found one of the Disa valves literally laying in the manifold completely broken off--if sucked in that would have been goodbye to the engine.

Otherwise lots of benign things cause rattling but if its only during acceleration--this is one of the fewer things that can do that. Search the web for DISA valve failure and do some reading
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