NefMoto > Technical > Tuning > RS6 TFSI Fueling wired problem ... need some help/advice
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Author Topic: RS6 TFSI Fueling wired problem ... need some help/advice  (Read 5267 times)
RS-MAD
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« on: May 29, 2014, 10:13:29 AM »
I have RS6 with upgraded HPFP , pump is calibrated in soft and car is holding fuel pressure fine until 6200-6300 rpm . Then fuel pressure is starting to rise and hits 150bar. When that happen car is stalling something like limp but no error.Requested FP is 120bar.
Other strange is that I have other cars with same HW changes and same pumps and they runing just fine.
What can cause that in fuel system ? Some advise ?

Thanks !
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julex
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« Reply #1 on: May 29, 2014, 10:49:23 AM »
Quote from: RS-MAD on May 29, 2014, 10:13:29 AM
I have RS6 with upgraded HPFP , pump is calibrated in soft and car is holding fuel pressure fine until 6200-6300 rpm . Then fuel pressure is starting to rise and hits 150bar. When that happen car is stalling something like limp but no error.Requested FP is 120bar.
Other strange is that I have other cars with same HW changes and same pumps and they runing just fine.
What can cause that in fuel system ? Some advise ?

Thanks !

If RS6 has returnless fuel system and PWM signal is used to modulate the pump then obviously it is getting too much duty causing the pressure to rise. If it has FPR and return, then the pump is overcoming the FPR return line causing the pressure rise. Either way it sounds like PWM duty cycle is simply too high...
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ddillenger
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« Reply #2 on: May 29, 2014, 11:03:13 AM »
Quote from: julex on May 29, 2014, 10:49:23 AM
If RS6 has returnless fuel system and PWM signal is used to modulate the pump then obviously it is getting too much duty causing the pressure to rise. If it has FPR and return, then the pump is overcoming the FPR return line causing the pressure rise. Either way it sounds like PWM duty cycle is simply too high...



This is TFSI. Whole new ballgame.
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Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience!

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julex
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« Reply #3 on: May 29, 2014, 11:16:28 AM »
Quote from: ddillenger on May 29, 2014, 11:03:13 AM
This is TFSI. Whole new ballgame.

Ah right, duh. I thought older RS6.
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ddillenger
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« Reply #4 on: May 29, 2014, 11:23:59 AM »
Quote from: julex on May 29, 2014, 11:16:28 AM
Ah right, duh. I thought older RS6.



Heh.

I hope I didn't sound condescending there. Wasn't the intention.
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julex
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« Reply #5 on: May 30, 2014, 09:27:58 AM »
Quote from: ddillenger on May 29, 2014, 11:23:59 AM
Heh.

I hope I didn't sound condescending there. Wasn't the intention.

Not at all. I should have paid more attention, especially when I saw 120bar pressure Smiley
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B234R
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« Reply #6 on: May 30, 2014, 11:40:41 AM »
Maybe the fuel high pressure sensor (rail pressure) is broken.

I've seen a very similar issue on a MK5 GTI I was working on.
On that particular car rail pressure was fine up to 6700 rpm, after that point it spiked over 150 bar and the engine started to sputter. (cut-out like)
No errors or other problems.
New sensor, everything was fine again.
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majorahole
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« Reply #7 on: June 02, 2014, 10:25:01 AM »
could it be the fuel pressure relief valve sticking??
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RS-MAD
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« Reply #8 on: June 03, 2014, 01:11:00 AM »
Quote from: majorahole on June 02, 2014, 10:25:01 AM
could it be the fuel pressure relief valve sticking??
RS6 use Gen3 HPFP and relief valve is inside pump . Im using brand new pumps , and testes with 3 sets . So I asume problem is not relief valve.
Will try to change fuel pressure sensor.
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