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Old 01-28-2013, 08:15 AM
ninetyseven1 ninetyseven1 is offline
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Location: Lewes
Join Date: Jun 2012
Posts: 83
Mein Auto: 1997 540i
Originally Posted by FLE39 View Post
Guys, I've been running 89 in my car since I bought it. Rattles somewhat depending on throttle. I have done just about every tune up item possible. Plugs, CCV system, O2's, cooling system, fuel filter, DISA valve. What else in gods name can be causing it? I thought the car has a Knock sensor and 89 under "normal" conditions would be ok. If I run 93 it goes away. I know the answer I'm going to get... run 91+. but a stock car like this under a watchful eye and in great shape should run on 89 w/out rattle. Is my Knock sensor bad? No CEL.
When I had a vacuum leak, it made the car knock. Check all hoses. Mine was the hoses that came off of the MAF boot and went to the front of the intake. There are like 3 hoses there.
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