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Author Topic: M3.8 BAT fueling  (Read 3254 times)
IAmAnEngineer
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« on: January 20, 2021, 02:50:01 PM »

Hi,
I've been tuning a 018R with ols300 and wideband lambda tool for a gt2871r.

Fueling is done with KHFM (=load) and afterwards with KFLF, FGAT0 is stock at "1".

Load stays at max. 10.5ms at full load, car runs pretty good.
Idle and part throttle are perfect.
WOT works fine, too, but only in the lower gears.

But I got the problem, that only in higher gears, above 5500 rpm, it leans out very fast and EGT rises up.
No matter, how much I rise up KFLF (even to astronomical values), it still leans out.

Injectors are Bosch EV14 875ccm with Bosch 044 pump, so they are big enough.
Load limiters are all FF'ed, MAF Limiter too, for testing.

KFTLWS is stock, I never needed it so far.
I couldn't find much information about that map. Can someone confirm, that it is only used, when MAF is faulty/unplugged as a backup-value for Load?

KFBAKL (=accel enrichment) is stock, too, never needed it so far.
By stock, it stays at the same value at higher rpms and 90° engine temp, so IMO it couldn't be the reason for leaning out at high RPM.
Else I would have that problem earlier...  Huh

Does someone have a tip for me, what I may have forgot?
Maybe just a hardware fault..??
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eliotroyano
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« Reply #1 on: January 21, 2021, 06:35:41 PM »

Maybe a comment can be done if you share some logs and more info about your tune. In general tune big injectors in M383 needs good work. I do not remember if your version had EGT compensation. Also if you leave FGAT0 and KFTLWS stock you shold set KFLF at very low factors for that big injectors. That could be your problem. Just some comments or ideas.
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IAmAnEngineer
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« Reply #2 on: January 22, 2021, 07:02:00 AM »

Thanks for your answer!
Sorry I don't have any logs, tune was done on-the-fly and I only used VCDS for checking values...
I will do some logs next time.

I didn't think about the EGT calculation! Maybe thats the reason for all trouble


FGAT0 is stock because I did load and fueling just by KHFM, fine-tuning done with KFLF.

Can you explain me, what KFTLWS is for?
I know it's an map for load, dependent on throttle position. But load calculation is only done with airflow and KHFM, so what is this map for?
Only for limp mode maybe?
« Last Edit: January 22, 2021, 07:04:20 AM by IAmAnEngineer » Logged
Super1600
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« Reply #3 on: April 18, 2021, 10:04:04 AM »

hey, may I ask if you have been able to solve your problem?
I'm interested in the root cause of lean fueling @ high revvs you described.
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1.8T w. M3.8.2
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prj
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« Reply #4 on: April 19, 2021, 08:31:33 AM »

Most likely it either wasn't "leaning out" because he didn't use anything to measure it with except his finger or he did measure the AFR and it was leaning out because of the fuel pump not being able to supply enough fuel.

Certainly NOTHING to do with tuning in this post though. Forget it.
Fit a fuel pressure gauge and look at your fuel pressure if you are having this problem. 99% the problem is there.
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IAmAnEngineer
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« Reply #5 on: May 17, 2021, 06:32:58 AM »

@prj: as stated above i used a lambda tool (innovate lm2)

Issue was solved after customer found out his fuel pump was broken.
Car now runs fine at 445hp
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prj
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« Reply #6 on: May 17, 2021, 10:22:41 AM »

Option b) it was then.
Basics, always remember the basics Wink
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IAmAnEngineer
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« Reply #7 on: May 17, 2021, 10:25:04 AM »

Yep  Wink
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