notoriousg
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« on: September 26, 2025, 03:01:34 PM »
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Hey, guys
first i would like to thank you for the great community, which has helped me learn a lot by reading the threads in various occasions.
I started learning tweaking and learning motronic by playing around with my MED9 BWA A3 8p. I am constantly refering to S4 wiki,
which is a big help even on a newer ECU. I`ve done a tune on it and i am somehow happy with how it turned out for my first attempts.
The car is completely stock for now. I am trying to tune it for 1 bar boost across the rev range as close as possible, but i am getting
a boost drop. Initially it was peaking at 0.8 bar quite late at 3800 rpm and dropping to 0.5 at higher rpm, then i tweaked the boost PID
and managed to get it peak to 1 bar at around 2800 rpm, which is a good sign, but it still doesn't manage to hold it at higher rpm and drops
to around 0.7 bar. I am using VAGCOM to log the car and here are some logs.
The initial ones start with LOG-XXX and the latter ones are mod6_X.
Any advises are appreciated!
Thank you.
Edit: Applied proper Vehical logs.
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« Last Edit: September 29, 2025, 02:25:18 PM by notoriousg »
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ABEPerformance
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« Reply #1 on: September 30, 2025, 11:37:42 AM »
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hello first of all you can start by doing a log from 1200rpm in 4th gear till redline and stop there ! after this you should do more research on which maps need modification ! good luck !
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notoriousg
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« Reply #2 on: October 01, 2025, 12:24:30 PM »
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hello first of all you can start by doing a log from 1200rpm in 4th gear till redline and stop there ! after this you should do more research on which maps need modification ! good luck !
Hey, I am thinking that it might be a mechanical issue i am having with the boost, since KFLDIMX is scaled to 1 bar boost request i shouldn't need to change it to run 1 bar. I will check the Waste gate solenoid. |
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« Last Edit: October 01, 2025, 12:42:38 PM by notoriousg »
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Nitefly
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« Reply #3 on: October 12, 2025, 12:49:32 AM »
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Hello. I have not had the time to look at your logs, but always good the check a turbo car for airleaks, a smoke machine is very good for that.
Have you seen/read the MED 9.1 tuning thread Basaono did? I remember, he hade the same issue, not reaching target boost at higher rpm‘s. Could be your spring in wastegate actuator which is too weak…. or some may the hoses around the N75 you could check or the N75 it self…
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notoriousg
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« Reply #4 on: October 18, 2025, 01:02:28 PM »
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I tried reviving the MED9.1 basics thread, but with no luck, so i`m posting here. Went back to stock and doing logs. I am trying to figure out a couple of things, before i try to tune.
1. Why is mimax dropping @5k rpm
2. Why fr_w (STFT i think) sky rocket @5.5k rpm and prroh (rail pressure) drops @5.5k rpm
3. Is it normal for the ECU to pull timing on the stock tune.
Logs of 4th gear ~2k rpm to 6300 rpm attached.
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notoriousg
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« Reply #5 on: December 11, 2025, 03:04:55 PM »
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So i have attached the latest logs i have done, where it seems i have fixed the over fueling issue by adjusting KFLBTS. I felt like i should leave TABGTA alone and mess with BTS.
Under boosting issue persists so i guess either i need a downpipe to get rid of the cats or some preload on the WG actuator. I have also increased the rail pressure to 120 bar
and it seems to hold it, but i see my LPFP duty cycle goes to 92% and i think it is not keeping up. All hints based on the logs are appreciated.
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notoriousg
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« Reply #6 on: February 08, 2026, 12:25:26 PM »
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Okay, so i am at a dead end here.
No matter what i do the boost is not there. Boost request is okay, i don't see any torque interventions by checking what is written in the s4 wiki.
Here is the latest file, can someone have a look and give me some info, what am i doing wrong? I tried all sorts of KFMIRL and KFMIOP strategies,
but with no avail. It looks like the WG spring is not stiff enough or it needs preload. The car has a downpipe and no cats.
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« Last Edit: February 08, 2026, 12:31:42 PM by notoriousg »
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VWvinny
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I live on turbo pressure—always ready to boost
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« Reply #7 on: February 09, 2026, 01:05:49 PM »
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Okay, so i am at a dead end here.
No matter what i do the boost is not there. Boost request is okay, i don't see any torque interventions by checking what is written in the s4 wiki.
Here is the latest file, can someone have a look and give me some info, what am i doing wrong? I tried all sorts of KFMIRL and KFMIOP strategies,
but with no avail. It looks like the WG spring is not stiff enough or it needs preload. The car has a downpipe and no cats.
Here, set them below each other in WinOls so you can compare and try them out. If you lower the LDRXN tables, you also lower the required boost. |
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notoriousg
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« Reply #8 on: February 09, 2026, 01:34:12 PM »
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Here, set them below each other in WinOls so you can compare and try them out. If you lower the LDRXN tables, you also lower the required boost.
Yeah i've set LDRXN high and i am using KFLDHBN for the boost setpoint, instead. |
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notoriousg
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« Reply #9 on: May 04, 2026, 04:42:55 AM »
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So i got to a point where i am happy with the car, runs ok i need to adjust the boost request to the actual boost and touch the timing, because there are CFs.
I am running the worst cheap fuel i can get, because i want to make the car run ok with it so it runs better with better fuel. One thing i noticed is the STFT
in the logs. I am asking for 0.813 lambda, and the STFT are around 5-6% sometimes 8% at gearshifts, but lamsoni_w shows 0.803-0.805 lambda.
With the positive STFT it means it's adding fuel. The car has a downpipe, rs4 FPRV, TTRS LPFP and everything else is stock. Is the MAF reading low values?
Faulty lambda sensor? Attached are the latest logs.
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« Last Edit: May 04, 2026, 04:45:16 AM by notoriousg »
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notoriousg
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« Reply #10 on: May 13, 2026, 01:25:18 PM »
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The car threw runner flap codes a few times, but clearing them made them go away. Yesterday i believe was the last breath of the flap motor, because the DTC codes are now permanent and cannot be cleared. I started reading the FR and also posts here in the forum, but can't find is the delete only setting all LBK control maps to 0, so they don't operate? I read that "doing it the proper way" won't require DTC deleting in the file, but i am thinking that setting them to always off in the maps will still throw DTC codes. The other thing i saw in the FR is setting bit 1 of CWLBK to true (Sollwert = Applikationswert) will make lbksol_w to come from FLBSAP, which is 0 in the file. Any guidance on this? I don't mind digging in the FR for answers, but at the moment i am stuck on which the correct approach is and which function to pay attention to... LBKSOL, ALBK, BGLBK, DLBK...
Thanks for any info.
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