N54 MHD - LTFT rises, STFT drops during WOT?? (log inside)

mariokadett · 11-25-2018, 05:34 AM

Hi guys,

owning a 335i e91 since last year I spend quite some time looking at yours threads to learn and tune my 335i.

now I am MHD stage 1+ v8 maps (FMIC installed yesterday) and I checked my logs to insure all is safe.

the car is driving perfectly and feels smooth and strong, however, I found out that the fuel trims behave strangely and I would like to understand the cause.
during cruising, the trims look normal, but in WOT, the LTFT rises to high positive numbers and STFT drop and finally are pegged at -34.

the AFR is at 11.6 at tend of the WOT which seems to be on the rich side but I don't knoz the target so maybe it is normal.
So what could be happening?

this log is just after FMIC install but it showed the same thing before.
on both stock power, stage 1 & 1+.

I leave at 350m above sea level and tempaerature are close to 0°c now in switzerland but it doesen't seem to be temp dependent.

stg 1+
https://datazap.me/u/mario69id/n54-m...og=0&data=3-23

stock power:
https://datazap.me/u/mario69id/stock...ata=1-17-26-27

I thought negative trims were to reduce fuel and get leaner and positive numbers to gt richer. but I don't understand that they go in opposite direction.

Hope that you can help me understand what is happening and what could be wrong.

thank you!

Chris@VargasTurboTech · 11-25-2018, 11:18 AM

Reset adaptations. I've seen issues with diverging trims before... assuming all is well mechanically (no boost leak with the FMIC install which is a definite thing to look for) an adaptation reset usually fixes it.

Chris

mariokadett · 11-25-2018, 12:47 PM

Thank you Chris!!

did it and it solved the issue!
the LTFT are now at 0 under WOT and STFT oscillate around -5/-10. AFR is closer to 12 now.

I new it was not from the FMIC assembly since the issue was happening on earlier logs. (leaks would still have been possible for sure).

11-25-2018, 05:34 AM	#1
mariokadett New Member 0 Rep 5 Posts Drives: E91 n54 2007 Join Date: Nov 2018 Location: Switzerland iTrader: (0)	N54 MHD - LTFT rises, STFT drops during WOT?? (log inside) Hi guys, owning a 335i e91 since last year I spend quite some time looking at yours threads to learn and tune my 335i. now I am MHD stage 1+ v8 maps (FMIC installed yesterday) and I checked my logs to insure all is safe. the car is driving perfectly and feels smooth and strong, however, I found out that the fuel trims behave strangely and I would like to understand the cause. during cruising, the trims look normal, but in WOT, the LTFT rises to high positive numbers and STFT drop and finally are pegged at -34. the AFR is at 11.6 at tend of the WOT which seems to be on the rich side but I don't knoz the target so maybe it is normal. So what could be happening? this log is just after FMIC install but it showed the same thing before. on both stock power, stage 1 & 1+. I leave at 350m above sea level and tempaerature are close to 0°c now in switzerland but it doesen't seem to be temp dependent. stg 1+ https://datazap.me/u/mario69id/n54-m...og=0&data=3-23 stock power: https://datazap.me/u/mario69id/stock...ata=1-17-26-27 I thought negative trims were to reduce fuel and get leaner and positive numbers to gt richer. but I don't understand that they go in opposite direction. Hope that you can help me understand what is happening and what could be wrong. thank you!
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11-25-2018, 11:18 AM	#2
Chris@VargasTurboTech Lieutenant Colonel 1933 Rep 1,532 Posts Drives: All Things TurboCharged Join Date: May 2016 Location: Bay Area iTrader: (0)	Reset adaptations. I've seen issues with diverging trims before... assuming all is well mechanically (no boost leak with the FMIC install which is a definite thing to look for) an adaptation reset usually fixes it. Chris
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11-25-2018, 12:47 PM	#3
mariokadett New Member 0 Rep 5 Posts Drives: E91 n54 2007 Join Date: Nov 2018 Location: Switzerland iTrader: (0)	Thank you Chris!! did it and it solved the issue! the LTFT are now at 0 under WOT and STFT oscillate around -5/-10. AFR is closer to 12 now. I new it was not from the FMIC assembly since the issue was happening on earlier logs. (leaks would still have been possible for sure).
	Appreciate 0 Quote