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vtraudt
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« on: January 12, 2013, 06:14:35 AM »
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Car has the Giac recommended setup (K04, FMIC, 315cc, DP) an AFPR.
Initially, fuel pressure was set low (forgot, but lower than 2.7 bar), I now set it to 43.5 psi (3.0 bar) with vac line disconnected (Giac specification).
With lower and now 'stock' fuel pressure, the car runs ok under WOT logs.
But part throttle (very little with the lower FP setting, a bit more with 3 bar), the car goes berserk and boost to 25 psi or more.
If getting out of throttle during such berserk runs, a massive jolt occurs.
What might be causing this behavior. First to0 lean, now too rich.
Some suggested 2.7, 2.8 bar; will try 40.5 psi.
Can coil packs or spark plugs cause such weird behavior?
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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nyet
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« Reply #1 on: January 12, 2013, 10:41:37 AM »
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Don't guess, log
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! 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 ex
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vtraudt
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« Reply #2 on: January 12, 2013, 12:28:47 PM »
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CAn only log with VAGcom, slow.
Did a throttle body alignment, seemed to help.
Will run more logs.
What parameters suggested?
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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vtraudt
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« Reply #3 on: January 12, 2013, 03:09:45 PM »
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Seems to run at 40 psi on the AFPR (vac disconnected).
With this setting:
- still some jerking when getting off PART THROTTLE boost (not so WOT).
- still boosting much higher at 40-50 degree throttle (up to 25 psi) vs. WOT (15 psi)
- NO codes/misfires
- looking at the logs, it seems clear that under part throttle, the N75 is not doing anything !!!! (numerical values zero).
- WOT N75 kicks in (high numerical values, until fading out at higher RPM)
I am trying to attach the excel file (complete run, several part and WOT runs)
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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vtraudt
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« Reply #4 on: January 15, 2013, 08:34:39 AM »
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Can someone clarify for me:
zero showing in log for N75 duty cycle means: N75 closed, not bleeding off boost. Spring holds wastegate shut closed.
99% showing in log for N75 duty cycle means: ECU tries to bleed off boost. N75 as open as possible, trying to push wastegate open to limit boost?
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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vtraudt
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« Reply #5 on: January 15, 2013, 08:36:49 AM »
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Still no progress in finding out what is going on.
Why is N75 NOT trying to limit boost, showing all zero 'waste gate duty cycle' under partial throttle (and boost going through the roof up to 25 psi), while cutting boost to 16 psi (and showing up to 99% duty cycle for the N75)?
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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elRey
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« Reply #6 on: January 15, 2013, 09:47:36 AM »
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N75 0% duty = wastegate spring only = ECU wants low/no boost
N75 95% duty = closed wastegate = ECU wants high/more boost
Something tells me your wastegate is stuck shut.
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« Last Edit: January 15, 2013, 09:49:26 AM by elRey »
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vtraudt
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« Reply #7 on: January 15, 2013, 09:58:15 AM »
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N75 0% duty = wastegate spring only = ECU wants low/no boost
N75 95% duty = closed wastegate = ECU wants high/more boost
Something tells me your wastegate is stuck shut.
Thanks. If wastegate is stuck shut, why boosting 16 psi under WOT, and 25 psi under partial throttle? Would it boost 25 psi all the time? I see if I can reach down there and manually move the wastegate actuator. |
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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nyet
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« Reply #8 on: January 15, 2013, 10:29:52 AM »
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Thanks. If wastegate is stuck shut, why boosting 16 psi under WOT, and 25 psi under partial throttle?
Would it boost 25 psi all the time?
Depends on your turbos, exhaust set up, and waste gate spring rate. At some point, exhaust gas pressure will open your waste gates for you. |
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! 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 ex
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elRey
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« Reply #9 on: January 15, 2013, 10:39:17 AM »
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Also, just because a turbo can reach 25 psi @ 3500 RPM doesn't mean it can hold that psi to redline.
A stock K03 on a 1.8t can spike 25 @ ~ 3000 with a closed wastegate, but then dies down to ~14 psi @ redline, still with a closed wastegate. The turbo just can't flow enough to feed the engine and maintain that pressure. Again with wastegate completely shut.
Not 100% sure if a K04 can hold 25psi @ redline.
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« Last Edit: January 15, 2013, 10:41:30 AM by elRey »
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vtraudt
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« Reply #10 on: January 15, 2013, 10:53:03 AM »
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The point is (just to clarify again):
N75 shows values at WOT, boost 16psi
N75 shows ZERO at part throttle, boosting (not spiking) 25 psi
Has someone logged his PC16 with WOT and partial throttle?
Stuck wastegate should be stuck at WOT or partial throttle.
Bad N75 should not work WOT and partial throttle
Leak/hose etc should be same for WOT and partial
I will look for another N75 to swap in.
I will try to move the wastegate by hand (hard to reach)
At next opportunity, I plan to swap ECU with other Giac (also PC16) I run in different car.
If I disconnect N75 (remove plug), what boost should I see?
If no solution can be found: put MBC in parallel to prevent high boost.
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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prj
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« Reply #11 on: January 15, 2013, 11:03:59 AM »
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If you disconnect N75 you will see spring boost.
Do this first before removing the wastegate or doing other things.
Then you will see if it's an electronical problem or physical.
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vtraudt
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« Reply #12 on: January 15, 2013, 11:16:37 AM »
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If you disconnect N75 you will see spring boost.
Do this first before removing the wastegate or doing other things.
Then you will see if it's an electronical problem or physical.
Will do that, thx. |
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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nyet
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« Reply #13 on: January 15, 2013, 12:15:20 PM »
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Not 100% sure if a K04 can hold 25psi @ redline.
Two can't on a 2.7t  |
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Logged
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! 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 ex
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vtraudt
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« Reply #14 on: January 15, 2013, 12:51:52 PM »
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Two can't on a 2.7t Not the point here what the turbo can do. |
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Logged
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
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