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      08-17-2024, 04:27 PM   #9
RocketyMan
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Drives: E53 X5, E83 X3, E93 M3
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2008 BMW M3 E93  [10.00]
Quote:
Originally Posted by Redd View Post
I give this advice because I spent 2 mths chasing an all cylinders misfire issue a couple years back. Tried everything - O2s, sparks, smoke/water test multiple times, all showed no issue. But the misfires persisted. In the end, I removed the entire plenum - engine running in alpha-n mode - and misfires went away. So I managed to localize the source of the problem - a vacuum leak somewhere in the plenum.

In the end, the leak was caused by some broken tabs in the IAT sensor hole. It would only leak under high engine vacuum, hence it passed all smoke tests.

AFAIK, S65 MAP sensor is pre-TB before the plenum. So any vacuum leak after the MAP - eg in the plenum - can cause misfires.
No. That's not how speed density works. The MAP sensor is connected to the idle strip which is communized AFTER each throttle plate...hence--vacuum.

Did you even review the link I posted?
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