BOosting too early.

[b5a4erik]

Hey all,

'99 A4, AEB, UM Stage 2 tune, K04, 440cc injectors, 3" MAF, stock TIP.

I'm boosting too early, the most relatable thing I can compare it to is a slipping clutch. When I give it a considerable amount of gas, the boost will get ahead of itself, boosting past where it should be I'm sure, until it seems like the computer realizes it and thus the boost "catches itself" to then boosting as it should, in unison with the gas I'm giving the engine... until I let off the gas again and give it another go. It also at times overboosts (not early, but too much once it's boosting, to like 26psi when it should be only 21).

My thoughts are a faulty N75 valve, but was also wondering if it could be the fact that I'm still using the stock TIP with a 3" MAF?

I've searched, please provide some feedback.

Regards,

~ ea

[Turbo_B5]

Sounds like the issue I have with my k04. I was thinking it was a faulty n75 so I threw in my newish one. no change so I was thinking it could be the stock TIP I am running.

subbed for answer.

[PsorianoPre99A4]

Hey I had this issue with that stage 3 tune of UM. I bought a MBC and it was solved.

- - - Updated - - -

Hey I had this issue with that stage 3 tune of UM. I bought a MBC and run it parallel with your N75 and solved my issue. However I am on the f21 turbo.

[PsorianoPre99A4]

Hey I had this issue with that stage 3 tune of UM. I bought a MBC and run it parallel with your N75 and solved my issue. However I am on the f21 turbo.

[MetalMan]

Yep, this is pretty typical for the UM tunes. They're sort of a "one size fits all" tune, which it does pretty well for the most part... but it's impossible for the tune to account for a specific turbocharger's spool capability.
As psorianoPre99A4 said, a MBC in parallel with the N75 is the way to stop boost spikes from occurring. This setup will still allow the N75 to function normally otherwise.

[redline380]

Maybe I'm missing something but how does boost come on too early? I would love to have that problem.

[Turbo_B5]

Cause it over boosts then the ecu corrects it's self. I'm also having problems with part throttle boost control. It fluctuates around what it should be holding. I'm running a k0mpresed tune.


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[b5a4erik]

Thanks guys,

I'll give the MBC in parallel a try.

Also bump for King.

[Turbo_B5]

Thanks guys,

I'll give the MBC in parallel a try.

Also bump for King.

I'm running a mbc in parallel and that fixed the boosting over 20 but hasn't fixed the part throttle boost control.

Stock tip
New n75
Forge 007
Straightpipe turboback
Stock smic
Junkyard map sensor
K0mpresed k04 stock injectors/maf



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[b5a4erik]

I'm running a mbc in parallel and that fixed the boosting over 20 but hasn't fixed the part throttle boost control.

This. Same thing for me.

[b5a4erik]

bizump.

[b5a4erik]

Anybody else got input?

[Believer]

Have you tried unplugging the n75 to see if it stops at wasegate pressure? The manual boost controller may work but if your boost is shooting up past where it's supposed to, your wasegate isn't functioning in some way, either a fault of its own or a failing n75.

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[Turbo_B5]

I have a new n75 so can rule that out.


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[Believer]

I have a new n75 so can rule that out.


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I'm confused. Are you b5a4erik? Does he have a new N75?

[Bordom]

I'm confused. Are you b5a4erik? Does he have a new N75?

b5a4erik bumped it for king while he does the MBC in parallel. Hope that clears up confusion

Everything graciously mispelled by Android

[Believer]

b5a4erik bumped it for king while he does the MBC in parallel. Hope that clears up confusion

Everything graciously mispelled by Android

Yes thanks. I missed the part where they were both having partial throttle issues also. Sure your wastegate lines are right and tight?

[Turbo_B5]

Yes thanks. I missed the part where they were both having partial throttle issues also. Sure your wastegate lines are right and tight?

Yea they are tight. Is it possible the wastegate is too tight or its just a shitty actuator?


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[b5a4erik]

Does the wastegate rattle on decal when it's too tight or too loose?

I'm also wondering about the actuator.

I've ran a NBC, but that also meant boosting to quickly it seemed.

[RENOxDECEPTION]

Does the wastegate rattle on decal when it's too tight or too loose?

I'm also wondering about the actuator.

I've ran a NBC, but that also meant boosting to quickly it seemed.

No.

When I had this happen to me I ran a MBC in parallel with an N75 and it both allowed me to set a hard maximum boost, and still have the ECU regulate it.

[b5a4erik]

?

Doesn't answer my question.

I'm currently running a MBC in parallel w/ an N75, and I have similar symptoms to King, controlled my boosting past where I should be (good), yet I still overboost too early.

Anyways I'm thinking something with my waste-gate or it's actuator... my waste-gate rattles on decal. Relative to my boosting too early issue?

[RENOxDECEPTION]

I highly doubt you'd be able to hear the wastegate "rattle" in the car.

post a .csv log of groups 115 118 and 001.

[b5a4erik]

I definitely have heard the waste-gate rattle before (when it was completely shot off into the cat), I then replaced the turbo, yet still have a rattle on decal, similar to when it was shot. Checked the new one, was still on there, tightened the actuator, yet still have a rattle, especially after I've been boosting.

Don't have vagcom :/

Sorry to keep this thread lingering but I'm really trying to get this resolved.

~~~

Anybody have any more thoughts on my original issue of: "Why is my turbo spooling to early?"

Thanks, guys.

[RENOxDECEPTION]

Why don't you have vcds?

[b5a4erik]

Because I'm as broke as my car is.

[Turbo_B5]

Because I'm as broke as my car is.

its free. lol.

[AudiNFS]

For one, you're describing overboost, not "boosting too early."

It just sounds like an issue with the tune to me, but you need to log via VCDS to look at more options

[b5a4erik]

its free. lol.

$99 for anything worth while I thought, plus the dongle?

As for the overboost/boosting too early comparison: Wouldn't overboost be boosting to 25psi when the tune is only set for 21? While boosting too early would be boosting 11psi @ 2000rpms - which is what I'm experiencing.

[Believer]

$99 for anything worth while I thought, plus the dongle?

As for the overboost/boosting too early comparison: Wouldn't overboost be boosting to 25psi when the tune is only set for 21? While boosting too early would be boosting 11psi @ 2000rpms - which is what I'm experiencing.

How do you know it shouldn't be boosting 11 psi @ 2k rpm? That seems like pretty normal behavior for a K04-15 turbo. My Frankenturbo Mixed flow will hit 5-6 psi by 2k rpm if i lay in to it and that has larger wheels than the K04-15. Usually during boost onset the N75 duty cycle is pretty high to keep the wastegate closed, thus allowing the turbo to spool up as fast as physically possible. Then as boost levels rise toward and achieve request, the N75 duty cycle decreases, allowing the wastgate to open and regulate the boost pressure.

I can't really think of a way that you would be boosting faster than desired, though. Boost onset/profile is a function of exhaust flow working against the turbine wheel size and exhaust restrictions. These are physical limitations, meaning for a given exhaust flow and turbine wheel size, you can only boost so fast and no faster. If your desired boost is 21 psi, the file will be written in such a way to achieve that as fast as possible, unless it is written to be a 'rod-safe' tune.

[b5a4erik]

Thanks for the expansive reply, Believer,

One thing I can say is: I'm sure the car is not boosting correctly.

Sometimes I'll boost to 18psi @ 2krpm, turbo squealing all crazy, until it catches itself and spools in unison with the engine. I could WOT from 2k on the highway and it'll overboost and shake the whole car when it catches itself.

However usually if I start boosting after 3.5krpm, it boosts fairly smoothly and steadily.

[RENOxDECEPTION]

What?

No one is going to respond if you use terms like "squealing all crazy", "in unison with the engine", and "catches itself"
What the hell do those even mean when it comes to a turbo?

If you want legitimate help, post logs from vcds, bite the bullet. $100 is the cheapest thing you'll be buying for this car.

[Seerlah]

Problem is right there in your sig. Get that fixed first...and we will go from there.

1999 A4 FWD AEB 1.8T ~ Atlas

Sorry, just busting chops! But it sounds like a waste-gate issue...which people have been saying for a while now.

But are you using a 3" MAF or just a 3" housing with stock element?

[RENOxDECEPTION]

http://www.totalcardiagnostics.com/s...-original-vcds


not a "real" cable per say, but it comes with a legitimate copy of the full version of VCDS.

I have used it and it works perfectly for every car I have used it on, even newer ones.


LOL @ mitch.

[b5a4erik]

Problem is right there in your sig. Get that fixed first...and we will go from there.



Sorry, just busting chops! But it sounds like a waste-gate issue...which people have been saying for a while now.

But are you using a 3" MAF or just a 3" housing with stock element?

Ha_Ha. I know...

Plan on tightening up my waste-gate soon.

I'm running the stock MAF sensor inside a 3" housing connected to the stock TIP.

What?

No one is going to respond if you use terms like "squealing all crazy", "in unison with the engine", and "catches itself"
What the hell do those even mean when it comes to a turbo?

If you want legitimate help, post logs from vcds, bite the bullet. $100 is the cheapest thing you'll be buying for this car.

That's the best way for me to describe what I'm experiencing, if you simply take a moment to decipher my idiot speak you'll understand... you have to feel what I'm saying.

As for the VCDS I realize its a valuable tool, it's on the list.