NefMoto > Technical > Diagnostics > 2.0TFSI MED 9.1 LAMBDA CONTROL 25% !
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Author Topic: 2.0TFSI MED 9.1 LAMBDA CONTROL 25% !  (Read 1008 times)
ABEPerformance
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« on: February 24, 2026, 04:20:16 PM »
hey guys.. im ecountering a very big problem lately with my 2.0TFSI ! (this is my own remap made by me i accept any comment on it) my lambda control goes 25% at 5500 ish RPM and i don t know why,rail pressure is there,fueling is all good i have changed LPFP/HPFP/Fuel Filter/ keep in mind there a 73 mm MAF mounted on this ,it has been rescaled as i think correctly ! i might be wrong who knows but it doesn t seem like it ! lambda control is good until 5000-6000 RPM point ! maybe it s too much for the stock hardware ? i not sure i ve seen other TFSI is running even more agressive remaps than this ! im going to attach a couple of logs ,the stock file/remapped file and please i really need help here ! thank you in advance (also the timing pull is caused by the stock MLHFM stock scaling)
« Last Edit: February 24, 2026, 04:28:47 PM by ABEPerformance » Logged
ABEPerformance
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« Reply #1 on: February 24, 2026, 04:26:35 PM »
Quote from: ABEPerformance on February 24, 2026, 04:20:16 PM
hey guys.. im ecountering a very big problem lately with my 2.0TFSI ! (this is my own remap made by me i accept any comment on it) my lambda control goes 25% at 5500 ish RPM and i don t know why,rail pressure is there,fueling is all good i have changed LPFP/HPFP/Fuel Filter/ keep in mind there a 73 mm MAF mounted on this ,it has been rescaled as i think correctly ! i might be wrong who knows but it doesn t seem like it ! lambda control is good until 5000-6000 RPM point ! maybe it s too much for the stock hardware ? i not sure i ve seen other TFSI is running even more agressive remaps than this ! im going to attach a couple of logs ,the stock file/remapped file and please i really need help here ! thank you in advance
forgot to mention for this test(logs) MAF scaling was left STOCK just to see if it would change anything but it made lambda control worse till 5500 rpm xD
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cherry
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« Reply #2 on: March 04, 2026, 07:13:47 PM »
http://nefariousmotorsports.com/forum/index.php?topic=24044.msg171664#msg171664

Maybe you should simply install S3 injectors?
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fknbrkn
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mk4 1.8T AUM
« Reply #3 on: March 04, 2026, 07:43:50 PM »
or run 140 bar with rs4 return valve
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ABEPerformance
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« Reply #4 on: March 05, 2026, 09:45:18 AM »
Quote from: cherry on March 04, 2026, 07:13:47 PM
http://nefariousmotorsports.com/forum/index.php?topic=24044.msg171664#msg171664

Maybe you should simply install S3 injectors?

so you are saying injectors are at fault here?
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cherry
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« Reply #5 on: March 05, 2026, 12:35:42 PM »
There is no "fault", your tuning is the problem, you are clipping injection time already.
Just calculate how much time is available for injection @6000rpm/60s= 100rps -> 1000ms/100rps = 10ms each engine rotation -> maybe 300° injection window, so 300°/360°=0,83 -> 10ms * 0,83 -> 8,3ms. @5000 it´s about 10ms.

I did not check your file, so maybe it´s not exact 300°, i already wrote details here what to check: http://nefariousmotorsports.com/forum/index.php?topic=24044.msg171664#msg171664

You can raise fuel pressure, higher lambda and inject a little earlier. Anyways this "problem" is known 20 years now, and there is a very simply fix for it. Just install S3 injectors. Your tuning does not fit your hardware. You are driving at a very small edge, this is not safe. If there is any other problem you will destroy your engine.
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ABEPerformance
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« Reply #6 on: March 05, 2026, 04:50:33 PM »
Quote from: cherry on March 05, 2026, 12:35:42 PM
There is no "fault", your tuning is the problem, you are clipping injection time already.
Just calculate how much time is available for injection @6000rpm/60s= 100rps -> 1000ms/100rps = 10ms each engine rotation -> maybe 300° injection window, so 300°/360°=0,83 -> 10ms * 0,83 -> 8,3ms. @5000 it´s about 10ms.

I did not check your file, so maybe it´s not exact 300°, i already wrote details here what to check: http://nefariousmotorsports.com/forum/index.php?topic=24044.msg171664#msg171664

You can raise fuel pressure, higher lambda and inject a little earlier. Anyways this "problem" is known 20 years now, and there is a very simply fix for it. Just install S3 injectors. Your tuning does not fit your hardware. You are driving at a very small edge, this is not safe. If there is any other problem you will destroy your engine.







okay ! i will do so i guess,yes my tuning is very agressive for the stock setup indeed it s actually meant to push the car ! but i will stat injecting earlier to see ! thank you !
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