Quote:
Originally Posted by Erinra
Anything else I missed so far?
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You can locate vacuum leaks by spraying some brake cleaner localized on rubber parts. Where there is a leak, the brake cleaner is sucked inside and burned, raising the RPM slightly.
Obviously be careful with this method and don't do this with a hot engine and hot exaust and spray in the direction of the hot exhaust as brake cleaner is obviously very flammable....
Another way is by injecting smoke into the inlet system by a specialized smoke machine (inlet has to be capped off).
Where the smoke comes out, there is your leak. However this requires that special smoke machine, which is a fairly expensive tool.
The rubber blind caps on the inlet manifold that can perish I was talking about are #15 and #17 in the link below
http://bmwfans.info/parts-catalog/E4...nifold_system/
The O ring of the air inlet temperature sensor can potentially also leak, however this is less common. I think the lower intake boot is the usual culprit. A tear there causes a significant size of a leak