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New Member
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Posts: 28
Join Date: Jul 2020
Car: 2007 335i
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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.
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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Junior Member
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Posts: 139
Join Date: Apr 2015
Car: 335i N54 2008
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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.
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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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Junior Member
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Posts: 305
Join Date: Apr 2016
Car: 335i 6MT RWD
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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
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The title says he has a DMFW
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Super Moderator
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Posts: 6,167
Join Date: Oct 2013
Car: e90 335i
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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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