Boosting inconsistently

[brandon91891]

My car is a stage 3- running Franken turbos at 19psi. I notice recently that sometimes the car only hits 15psi and other times 19 again. I smoke tested my system and found no leaks. I do not have a vag com at the moment but will be borrowing my friends next week to check actual boost vs requested.

Is there anything I should be looking for ?? Maybe my n75


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[FlyboyS4]

May want to log WGDC and some of the temps like IAT and Coolant.

[tate182]

Other supporting mods fuel pump injectors ect?

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[brandon91891]

Fuel pump and injectors are stock . Only mods are frankenturbos Full catless exhaust and I just put rs4 intercoolers on the car gathering the rest of my parts to go full stage 3. Car is running a daz tune


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[brandon91891]

Other supporting mods fuel pump injectors ect?

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Fuel pump and injectors are stock . Only mods are frankenturbos Full catless exhaust and I just put rs4 intercoolers on the car gathering the rest of my parts to go full stage 3. Car is running a daz tune


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[MacDaddy]

Mine was boosting inconsistantly like that, found a pre-turbo inlet leak

[brandon91891]

Mine was boosting inconsistantly like that, found a pre-turbo inlet leak

So that wouldn't show up in a smoke test I'm assuming?.



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[brandon91891]

Anyone have any recommendations on the best way to get vagcom ? I currently don't have a laptop. I should really just buy it and have my own. Are there any scan tools like the Schwaben that can do the same things as vagcom. I want to be able to take logs


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[MacDaddy]

So that wouldn't show up in a smoke test I'm assuming?.



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Not in my case, maybe if i leak tested a hot engine, it was the o-ring on the turbo inlet, green check valves, spider hose and PCV all new

[Jrich825]

Check all the lines running to the n75, buddy had the same issue we changed that line and his spark plugs cleared it right up.

[sb_gli]

Are you sure your tune doesn't taper boost towards redline (so stock fueling isn't pegged) and that's what you are seeing?

Your tune might call for 19-20psi from 3 to 4k, then 15 psi by 5k, then 12 by 6k... etc

[brandon91891]

[QUOTE=sb_gli;12039454]Are you sure your tune doesn't taper boost towards redline (so stock fueling isn't pegged) and that's what you are seeing?

Your tune might call for 19-20psi from 3 to 4k, then 15 psi by 5k, then 12 by 6k... etc[/

I am not sure as I bought the car with this tune but the car gets noticeably slower when I'm seeing 15psi on the boost gauge. And I've done multiple runs in the same gear and have seen it pegged at 19 to redline in the same gear the day before where it would only go to 15. I'm gunna have a chance to log some runs today I will post the results later.


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[landfill]

VAG X tool from ebay can perform most functions that vagcom can.
Julex had a thread on it a year or so ago. I own one and for $50 it's
very much worth the money.

[sb_gli]

[QUOTE=brandon91891;12039537]

Are you sure your tune doesn't taper boost towards redline (so stock fueling isn't pegged) and that's what you are seeing?

Your tune might call for 19-20psi from 3 to 4k, then 15 psi by 5k, then 12 by 6k... etc[/

I am not sure as I bought the car with this tune but the car gets noticeably slower when I'm seeing 15psi on the boost gauge. And I've done multiple runs in the same gear and have seen it pegged at 19 to redline in the same gear the day before where it would only go to 15. I'm gunna have a chance to log some runs today I will post the results later.


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Pay attention to RPM vs boost pressure. The gear you are in doesn't matter, but the engine speed does. I'd be a little timid holding 19psi on a K03, let alone a more efficient hybrid, until redline. There's not enough fuel with stock injectors to keep actual AFR at a safe level.

VAG X tool from ebay can perform most functions that vagcom can.
Julex had post on it a year or so ago. I own one and for $50 it's
very worth the money.

Or buy a $15 FTDI cable and use ME7Logger (and VCDS Lite)

[landfill]

^^^Either one I guess. Read this thread pretty good reviews:
http://www.audizine.com/forum/showth...M-replacement)

[FlyboyS4]

[QUOTE=brandon91891;12039537]

Are you sure your tune doesn't taper boost towards redline (so stock fueling isn't pegged) and that's what you are seeing?

Your tune might call for 19-20psi from 3 to 4k, then 15 psi by 5k, then 12 by 6k... etc[/

I am not sure as I bought the car with this tune but the car gets noticeably slower when I'm seeing 15psi on the boost gauge. And I've done multiple runs in the same gear and have seen it pegged at 19 to redline in the same gear the day before where it would only go to 15. I'm gunna have a chance to log some runs today I will post the results later.

If you're holding 19 psi to redline on K03's budget for new turbo's along with the diagnostic cable.

[brandon91891]

[QUOTE=FlyboyS4;12040188]

If you're holding 19 psi to redline on K03's budget for new turbo's along with the diagnostic cable.

Somewhere everyone got lost I am running f21 turbos not ko3s lol


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[FlyboyS4]

Somewhere everyone got lost I am running f21 turbos not ko3s lol

Just me.

[jpurre]

[QUOTE=brandon91891;12040205]

Somewhere everyone got lost I am running f21 turbos not ko3s lol


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The point is that you have stock fueling and holding that kind of boost with F21's, you will run out of fuel and go lean. So the tune probably tapers off quite a bit at the top to compensate, or you will go lean and pop your engine.

[brandon91891]

[QUOTE=jpurre;12040414]

The point is that you have stock fueling and holding that kind of boost with F21's, you will run out of fuel and go lean. So the tune probably tapers off quite a bit at the top to compensate, or you will go lean and pop your engine.

I get that but sometimes the car never goes past 15psi and it does not explain the car being noticeably slower


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[sb_gli]

I suspect that the tune is doing what it needs to do. We will all just speculate if you don't provide logs.

[brandon91891]

I suspect that the tune is doing what it needs to do. We will all just speculate if you don't provide logs.

I hope your right will post them asap
Appreciate the help


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