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dougs951s dougs951s is offline
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Default False misfires from DMFW above 6200 rpm? - 11-07-2020, 05:43 PM

Hey guys, I'm trying to figure out why I'm getting misfires in cylinders 4,5, and 6 at high boost, only above 6200 rpm.

I can run map 7 to redline all day and not have an issue, but map 6 misfires every time at 6200ish rpm, clears up immediately when i restart the car.

Car is FBO + 17T's running E30 with a stage 2 lpfp. I'm running the hybrid race BEF and ger ~20 psi peak in map 7, tapered to maybe 17 by 6200 rpm. on map 6 im getting 23 peak, and 21ish @ 6200 where it stars to miss. Logs look great. Car has six new index 12's, new 2 step colder plugs gapped to .018" and new coils, new o2 sensors, fresh walnut blast, ect. Very well taken care of car. I think it must be false misfire, but i though that was usually only cylinder 6 or maybe 5 and 6. I'm getting codes for all of bank 2. No other codes are present besides the misfire codes.

Car idles and drives great up until this happens. How can I check if this is the case? Reflash the BEF with misfire detection deactivated and do a test pull? Attached here is a log from today when it happened.
Attached Files
File Type: csv misfires map 6 E30 fuel.csv (9.5 KB, 20 views)


FBO + 17T's

JB4 Hybrid Race BEF

Stage 2 lpfp.

Last edited by dougs951s; 11-07-2020 at 07:32 PM..
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ferocious ferocious is offline
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Default 11-09-2020, 02:42 AM

Quote:
Originally Posted by dougs951s
Hey guys, I'm trying to figure out why I'm getting misfires in cylinders 4,5, and 6 at high boost, only above 6200 rpm.

I can run map 7 to redline all day and not have an issue, but map 6 misfires every time at 6200ish rpm, clears up immediately when i restart the car.

Car is FBO + 17T's running E30 with a stage 2 lpfp. I'm running the hybrid race BEF and ger ~20 psi peak in map 7, tapered to maybe 17 by 6200 rpm. on map 6 im getting 23 peak, and 21ish @ 6200 where it stars to miss. Logs look great. Car has six new index 12's, new 2 step colder plugs gapped to .018" and new coils, new o2 sensors, fresh walnut blast, ect. Very well taken care of car. I think it must be false misfire, but i though that was usually only cylinder 6 or maybe 5 and 6. I'm getting codes for all of bank 2. No other codes are present besides the misfire codes.

Car idles and drives great up until this happens. How can I check if this is the case? Reflash the BEF with misfire detection deactivated and do a test pull? Attached here is a log from today when it happened.



its most likely the car is detecting false knock from the performance clutch
since it goes away when switching to map 7 due to timing is more aggressive and less knock sensitivity

try desensitizing the knock sensors in MHD (for testing only) if it goes away, try getting a custom tune and tell your tuner the scenario regarding the misfires due to a performance DMFW



2008 335i N54 FFtech Top Mount single turbo Precision 6266
JB4 G5 , VRSF 7" FMIC , VRSF CP + HKS BOV, Tial Wastegates
BMS METH KIT IN CONJUNCTION WITH MMP PI WITH 1055CC INJECTORS, PURE M1 METH,TMAP 3.5,
FUEL-IT STAGE2 BUCKETLESS LPFP, RB PCV. JB$ MHD BACKEND FLASH, xHP Stage2 v1.5
more to come...

Last edited by ferocious; 11-09-2020 at 10:48 PM..
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KevinC39 KevinC39 is offline
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Default 11-09-2020, 05:02 AM

Quote:
Originally Posted by ferocious
its most likely the car is detecting false knock from the performance clutch
since it goes away when switching to map 7 due to timing is more aggressive and less knock sensitivity

try desensitizing the knock sensors in MHD (for testing only) if it goes away, try getting a custom tune and tell your tuner the scenario regarding the misfires due to a performance SMFW
The title says he has a DMFW
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Payam @ BMS's Avatar
Payam @ BMS Payam @ BMS is offline
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Default 11-11-2020, 03:33 PM

Sounds like you will need a SMFW and new clutch with the power you're hitting now.


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