Thread: N55 Lean Issues
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      02-12-2020, 09:22 AM   #5
bbnks2
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Drives: 135i N55
Join Date: Jan 2017
Location: NY

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Quote:
Originally Posted by TunafishE93 View Post
The lean conditions that I seen where not under load.. It was under normal running before the pull started.. The pull itself didn't look bad for air fuel mixture.. What I have read it a know problem with the MHD and n55 platform.. Easy to see just flash back to stock..
Idle lean codes usually point to a vacuum leak. Take a log at idle and note what your STFT are. IF they are way positive and AFR is leaning out then it's likely a vacuum leak (like the inlet pipe). Un-metered air is entering the system. Vacuum leak may also present as a boost leak under boost if it's a charge-pipe or something like that.
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