Mixture too rich causing misfires

nebula · 08-16-2023, 10:25 PM

I have a stock 2018 X4 M40i with 85,000 miles and the N55 EWG with the newer style HPFP. I’m throwing the 101F01 - Air mass plausibility, 102002 - Air mass too low, and 118002 - Mixture too rich. ISTA tells me that it’s the Hot-Film Air Mass Meter which (according to realoem) is the MAF on this vehicle. It has a major stutter at around 2000 RPM, backfires sometimes, and will jerk randomly while driving. If I drive it 10 miles or so, it will go into drivetrain malfunction/limp mode and throws misfire codes on cylinders 1, 2, and 3.

I ran all of the ISTA tests that I can think of and it showed me that several things were bad and needed to be replaced. Most of those replacements cleared in ISTA once replaced with OE/OEM parts and seemed to make a difference until it didn’t.

Made things better:
Battery + Coding - ISTA suggested replacement and corrected after replacement
Air Filter - Extremely dirty and needed
Plugs - ISTA suggested replacement and corrected after replacement (Plugs 1, 2, and 3 - looked like you would expect with too much fuel and misfiring)
Ignition Coils - ISTA suggested replacement and corrected after replacement
Fuel Injectors (EU6 do not require coding) - ISTA showed all 6 as severely leaking, replaced and no longer shows as leaking in ISTA

Made things worse or didn’t seem to help:
MAF Sensor - ISTA shows this is the reason for my 101F01 code. Cleaning the old one seemed to help for a bit, replacing with new did not seem to help at all
MAP & TMAP Sensors - cleaned and swapped with each other. No new codes, but possibly made things worse. ISTA shows that both are working correctly.
HPFP - No difference

I have also ran tests on the VANOS solenoids, Valvetronic System, Fuel System tests, Readapted with the purge system unplugged for 15 minutes, smoke tested with no leaks discovered, crankshaft pressure tests, and PCV seems to be okay.

Any suggestions? Thanks in advance!

pokerface · 09-27-2023, 08:51 AM

N20, but hope its of some help

CELs, start up stumbles/stalls, and poor fuel economy were getting quite frequent with our 2013 N20 with 85,000 kms

Error code pulled was:

104301 Absolute pressure sensor, intake manifold plausibility, overrun: pressure too high

Cleaning the MAF and TMAP did not help.

What we did do was spray an almost entire can of CRC GDI Intake cleaner into the TMAP hole, that seems to have helped.

Three weeks on no CEL after the first run following cleaning procedure. Seems to run smoother (could be in my head). Will keep monitoring.

Assortment of previous issues in the past year:
-plugs and coils causing misfire (cheap Bosch set - probably only had about 3000kms on them before I went back to NGK and Bremmi)
-potentially(?) wonky tuning module causing misfire/errors

08-16-2023, 10:25 PM	#1
nebula New Member 0 Rep 5 Posts Drives: e90 - 2007 335i Join Date: Mar 2014 Location: Nashville, TN iTrader: (0)	Mixture too rich causing misfires I have a stock 2018 X4 M40i with 85,000 miles and the N55 EWG with the newer style HPFP. I’m throwing the 101F01 - Air mass plausibility, 102002 - Air mass too low, and 118002 - Mixture too rich. ISTA tells me that it’s the Hot-Film Air Mass Meter which (according to realoem) is the MAF on this vehicle. It has a major stutter at around 2000 RPM, backfires sometimes, and will jerk randomly while driving. If I drive it 10 miles or so, it will go into drivetrain malfunction/limp mode and throws misfire codes on cylinders 1, 2, and 3. I ran all of the ISTA tests that I can think of and it showed me that several things were bad and needed to be replaced. Most of those replacements cleared in ISTA once replaced with OE/OEM parts and seemed to make a difference until it didn’t. Made things better: Battery + Coding - ISTA suggested replacement and corrected after replacement Air Filter - Extremely dirty and needed Plugs - ISTA suggested replacement and corrected after replacement (Plugs 1, 2, and 3 - looked like you would expect with too much fuel and misfiring) Ignition Coils - ISTA suggested replacement and corrected after replacement Fuel Injectors (EU6 do not require coding) - ISTA showed all 6 as severely leaking, replaced and no longer shows as leaking in ISTA Made things worse or didn’t seem to help: MAF Sensor - ISTA shows this is the reason for my 101F01 code. Cleaning the old one seemed to help for a bit, replacing with new did not seem to help at all MAP & TMAP Sensors - cleaned and swapped with each other. No new codes, but possibly made things worse. ISTA shows that both are working correctly. HPFP - No difference I have also ran tests on the VANOS solenoids, Valvetronic System, Fuel System tests, Readapted with the purge system unplugged for 15 minutes, smoke tested with no leaks discovered, crankshaft pressure tests, and PCV seems to be okay. Any suggestions? Thanks in advance!
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09-27-2023, 08:51 AM	#2
pokerface Colonel 430 Rep 2,527 Posts Drives: F25 X3 N20 / F80 ZCP Join Date: Apr 2006 Location: Toronto iTrader: (1)	N20, but hope its of some help CELs, start up stumbles/stalls, and poor fuel economy were getting quite frequent with our 2013 N20 with 85,000 kms Error code pulled was: 104301 Absolute pressure sensor, intake manifold plausibility, overrun: pressure too high Cleaning the MAF and TMAP did not help. What we did do was spray an almost entire can of CRC GDI Intake cleaner into the TMAP hole, that seems to have helped. Three weeks on no CEL after the first run following cleaning procedure. Seems to run smoother (could be in my head). Will keep monitoring. Assortment of previous issues in the past year: -plugs and coils causing misfire (cheap Bosch set - probably only had about 3000kms on them before I went back to NGK and Bremmi) -potentially(?) wonky tuning module causing misfire/errors
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