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Author Topic: Issue with overboost and underboost MED9.1 2.0 TFSI BWA  (Read 482 times)
olobolo1996
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« on: October 08, 2019, 01:51:22 PM »

Hey there. I am new to the forum and to the beautiful world of EFI Tuning
A have an issue with my 2007 Audi TT 2.0T BWA. Around 2000-3000RPM with ~30% Accelerator Pedal position I hear my DV screaming like a wild pig. I have made couple of logs with VCDS and figured out that i
Actual Boost is lower than Specified Boost (which confuses me- why would the DV open during underboost?). In that situation the Actual Load is lower than Specified Load. Is there something limiting load then? Ive checked KFMIOP couple of times which is a perfect „invertion” of KFMIRL, also LDRXN makes no restriction to the load. What is interesting, in logs there is a big difference between actual and specified load. Below are some screens from logs and my KFMIRL and KFMIOP.


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mistertt2018
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« Reply #1 on: October 09, 2019, 03:26:17 AM »

hmmm, do you have the "old" style membrane DV? I'va the same care/engine/my and I had this membrane style DV - and this membrane got destroyed - so it won't seal anymor, making some crazy noise :-(
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olobolo1996
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« Reply #2 on: October 09, 2019, 06:26:47 AM »

hmmm, do you have the "old" style membrane DV? I'va the same care/engine/my and I had this membrane style DV - and this membrane got destroyed - so it won't seal anymor, making some crazy noise :-(

I have piston style DV, the proper D revision. The problem is, that the car overboosts. I have increased KFMIRL (in pair with KFMIOP) couple of times and it doesnt stop it from overboosting. Strange thing is that the current load doesnt reach specified load, which makes me think that something is limiting the load.


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soul87
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« Reply #3 on: October 10, 2019, 12:48:46 AM »

If actual is not reaching specified KFMIOP and KFMIRL have nothing to do with it...

Please share the normal logs with problem.
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mistertt2018
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« Reply #4 on: October 10, 2019, 03:29:28 AM »

@olobolo1996 - is the software original or did you already changed some maps?
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olobolo1996
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« Reply #5 on: October 10, 2019, 01:42:07 PM »

I noticed my first post was a bit messy- sorry for that, lack of time.
The car is Audi TT with hybrid K03 turbo, 3inch custom full straight exhaust, custom intake and bigger intercooler. Below is log from my run today. I made second log with WOT, but it failed to save. Anyway under WOT there is solid 1,4-1,5 Bar of boost and no issues. The problem happens under 20-30ish % of pedal as you see on the logs. There is overboost condition. That is why I have been increasing KFMIRL (and decrease KFMIOP) couple of times. There is still issue with this range of throttle especially in 1500-3500RPM. My DV is screaming and then the car goes into limp mode. As you see in the log file, specified load has big value, however actual load stays very low. LDRXN and KFLDHBN are increased so they do not cap the load. It all makes me think that:
1. There is something more limiting
2. I messed up some map.
In addition I made KFLDRL and KFLDIMX map first and haven't changed it since I started adjusting KFMIRL. I am trying to adjust KFMIRL to KFLDRL and then make some small fixes to the KFLDRL, but maybe it is a wrong attitude.
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mistertt2018
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« Reply #6 on: October 12, 2019, 10:11:42 AM »

What SW version is your ecu? Can you tell mit SW & HW Number- maybe i can have a look.

I'd got an K04-64 with downpipe, large intercooler, S3 Injectors and stock intake. I go for 1.3bar at most - more is not hadleable by the front tires. I've absoulutely no overboost at any time, because in my opinion a very smooth build up of boost is ways faster for a front wheeler, than that tdi style overboost, which just makes a pair of black stripes.

Also helpful, to post your file.

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olobolo1996
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« Reply #7 on: October 15, 2019, 11:11:16 AM »

My SW number is 1037386455. Below there is my file. Can you take a look at it and tell me if it is ok?

https://drive.google.com/file/d/1ZMYURrYh0cf_1ByQWvCgqMVyIA1_m_3o/view?usp=sharing
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prj
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« Reply #8 on: October 15, 2019, 11:18:25 AM »

You are changing random maps without understanding what they are doing.... You are going to get nowhere with this approach.
Start from basics.

Flash stock and don't make random changes to random maps. Your modifications look like 3 year old baby playing with keyboard Sad
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olobolo1996
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« Reply #9 on: October 15, 2019, 11:27:29 AM »

Well, I have read S4Wiki couple of times, I have been through many posts here, I do what they are doing, but it makes no change in the way I want it to. Maybe, some more detailed hint?
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prj
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« Reply #10 on: October 15, 2019, 12:05:03 PM »

You might have massive torque intervention due to raping all the torque control maps.
Put KFMIRL and KFMIOP to stock, you don't need to touch them at all for this.
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olobolo1996
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« Reply #11 on: October 15, 2019, 12:14:21 PM »

You might have massive torque intervention due to raping all the torque control maps.
Put KFMIRL and KFMIOP to stock, you don't need to touch them at all for this.

I thought I would need to increase the load KFMIRL to allow for the bigger boost pressure.
Where is that intervention from? KFMIOP? LDRXN? Stock KFMIRL is up to 176%. Is it enought for the 1,5Bar of Boost?
The S4Wiki says that the load*10+300 gives us manifold absolute pressure
For 176% it is 2060 which is around 1Bar of Boost.
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cherry
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« Reply #12 on: October 15, 2019, 12:59:13 PM »

Maybe it´s a mix from everything? Wink

Hybrid turbo, wastegate spring, compressor surge, wrong map-sensor, etc. and a mixed up file? Tongue

I would start with a "common" setup and start with some BHZ / CDL file.

What is the benefit from "K03 hybrid" to a standard K04?
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olobolo1996
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« Reply #13 on: October 15, 2019, 01:08:09 PM »

My stock turbo was leaking some oil and to big play on shaft. Instead of refurb I went for hybrid. Small difference in price, much better result. It has stock wastegate spring, the MAF sensor was working pretty well under previous tunes in my local workshop, so I guess it is ok.
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cherry
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« Reply #14 on: October 15, 2019, 02:13:23 PM »

Anyway you know that there is a limit with BWA map-sensor? Wastegate spring is stock, and adjustment?

When did these problems occure? You only change the turbo compared to older setup which was working fine?
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