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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > RPM drops below idle and almost stalls



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      02-19-2024, 10:42 PM   #1
bmuum3
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RPM drops below idle and almost stalls

Having an issue where car sounds like it has a big cam. Once it's warm I rev it to 2k RPMs and let off the gas. The RPMs drop all the way to the 300s and the car almost stalls and then recovers back to normal idle. I don't get any check engine lights or codes.

LPFP is brand new and never drops below 60
Injectors are tested and good. No leaks
New coil packs and spark plugs.
New o2 sensor
New valve cover gasket.
MAP and TMAP have been cleaned
PCV delete and flapper delete, straight to catch can which VTA
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      02-20-2024, 12:34 PM   #2
iqraceworks
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Quote:
Originally Posted by bmuum3 View Post
Having an issue where car sounds like it has a big cam. Once it's warm I rev it to 2k RPMs and let off the gas. The RPMs drop all the way to the 300s and the car almost stalls and then recovers back to normal idle. I don't get any check engine lights or codes.

LPFP is brand new and never drops below 60
Injectors are tested and good. No leaks
New coil packs and spark plugs.
New o2 sensor
New valve cover gasket.
MAP and TMAP have been cleaned
PCV delete and flapper delete, straight to catch can which VTA
Record a log and see what's going on. Are your AFR's getting crazy rich when it tries to stall out? If so...I would double check to make sure your injectors aren't leaking.

Am I understanding that right....you have a PCV setup with no flapper/check valve, and you vent to atmosphere? Isn't that just giving you one big vacuum leak?

Also...what is your LPFP pressure at idle? It should be right around 72-80 psi.
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2007 335i, BMS DCI, BMS Chargepipe w/Tial BOV, ARM Catless Downpipes, silicone inlets, Bilstein B12 Prokit Suspension, Whiteline subframe bushings, Front/Rear M3 control arms, G-Plus FMIC, Stage 2 LPFP, Custom E40 tune by Justin (V8Bait), xHP stage 3 transmission flash, RB Two Turbos....10.90 @ 128mph
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