Vacuum/boost leak?

[lynx]

hy guys,

I have one problem.
Recently I installed k26/t04 hybrid turbo and now, some kind wierd problems. It doesn' t mean, that it is connected with turbo.
I' ll tried to search the same kind on problem, but I didn' t find ...

Anyway, @ the moment I "driving in" turbo.
First problem is that, by - pass is chattering, when I change gears. Not always, when I push harder, only then (default wastegate setup at the moment, max. 1bar overboost). With 0.5bar overboost, it' s ok.
I' ll tried differert by - pass, result is the same.
I even changed the vacuum pipe, witch comes intake mainfold. Nothing

And one more thing.
When I push a little bit harder I could hear . . . how I say that. Some kind of noise, allmost the same bypass chattering, but it isn' t. I heard that voice, when I' m accelerating. I have cone filter, and I hear it very well. It isn' t so noisy like bypass, but I hear it.

Could anyone told me, what causes that kind of noises?

with best regards,

[BosnianS2]

I think the noise that you are hearing is normal. The turbo that you put on is pushing lot more air than the original K24, so when you change gears by-pass valve releases all the air in front of the turbo and you hear it through your filter.
Also you said that you are running default wastegate, i assume you mean you have no lines hooked up to the wastegate, that will also cause chattering noise. reason is because wastegate does not open slowly, instead exhause pressure it self is opening wastegate by pushing on the bottom of wastegate valve.
Spring inside the wastegate is trying to keep it closed but presure underneath is trying to open and that up and down motion of wastegate valve is making the sound that you are hearing
hopefully this hepls

[lynx]

BosnianS2, thanks for Your' s help.

At the moment all pipes is connected. I mean, pipe witch comes form solenoid valve is connected and ECU cuts boost @1bar. At the moment it' s normal, I' m "driving in" turbo.

Anyway, I know that chattering isn' t good for turbo health, so I have to solve that problem.

I use custon bypass valve:

http://www.friikartul.ee/albums/17-05-2005-18-05-2005/DSC08842.jpg

And there' s possibility to change springs. I just talked to man, who sells me that and he suggested harder spring. Hmm, could this help me? I mean, how could harder spring make "chattering" go away? Ok, it doesn' t open so easy anymore, but chattering? I' m only using a 1bar overboost. Original Audi TT bypass does do the same thing. Ok, TT bypass is not intended for such kind of turbo.

thanks again

p.s> if I get time and some harder spring, I will test it

[lynx]

hi again,

There was after all a boost leak. I mean, this wierd sound, when I was accelerating . . . hose witch comes intake and goes to the idle stabilisation valve. There wasn' t any hole that I could see, but when I changed this hose, there isn' t that noise anymore.

But there' s one problem, that not solved yet.
By-bass valve don' t open if boost exceed 0,5-0,6bar. Then I could hear very clear "chattering." Could this be a vacuum problem, or something? I changed the pipe, between mainfold and by-pass, nothing.
Could anyone suggest somethig, what may help

with best regards,

[newsh]

Some people have better results fitting the bypass valve (BV) backwards, but I don't know how to tell you which way round it should be.

Maybe you have a leak on the BV actuating hose, the small one from the inlet manifold.

[lynx]

Some people have better results fitting the bypass valve (BV) backwards, but I don't know how to tell you which way round it should be.

Maybe you have a leak on the BV actuating hose, the small one from the inlet manifold.

thanks

I tried to backwards, and that' s even worse. When pressure exceed 0,3bar I could hear a chattering.

I hope, there isn' t any leak . . . I mean, the small connector form inlet mainfold.

At the moment I don' t have any time, but what else I could check?

with best regards,

[lynx]

hi again,

Now, I have done some test.

First . . . all hoses, under hood, witch comes form intake have replaced, nothing.

I' d tried to vend air to atmosphere (maybe the hose to little, just tested), nothing again.

Next I' ll triet to use bigger hose for bypass valve (vacuum), maybe original size to small. I replaced it with 6mm hose, again nothig

Finnaly, I just tested harder spring for bypass and gues what . . . again nothing. With harder spring, bypass doesn' t open at all and I could hear chattering any boos level, wich is bigger than 0,1-0,2 bar.

The turbo gauge shows vacuum level on place run, -6 . . . like it show allways.

Now, I' m running out of any ideas . . .

Anyone?

[lynx]

hi again

Now I have done some other test, with my friend.

We checked all hoses, etc, etc . . . nothing . . . even crankcase breather, nothing

Finally we tested bypass on the place. Guess what, it' s chattering about 6000-7000rpm and when I loose gas pedal . . . chattering could hear. So, we wanted to know is bypass open in this time . . .we tooked the bypass and . . . it' s open, and turbo chatters. Nice one . . . looks like this custom made bypass could not let pass air enough. Wierd is only that, original audi TT is doing the same thing.

Ok, next thing I will add another bypass and if it will again chatter, I will put k24 with original EM back I sell my car!

[lynx]

problem solved with additional bypass

But now, there' s small boost leak, but I will find it and replace the hose

[4WheelDrifter]

You now need 2 DVs.
Looks like you pretty much sorted this one by yourself.

[lynx]

You now need 2 DVs.
Looks like you pretty much sorted this one by yourself.

DV? Hmm, what is the difference with DV and bypass? I' ll have read may threads in this forum and in some threads looks like it is the same?

Anyway, I can' t find the leak.
I hear hissing noise when I accelerate. Today we tested under pressure turbo hoses etc. nothing. Even with 3bar. Everything seems to be ok.

But when I accelerate, I could head pulsating noise and at the same time, turbo gauge is jumping . . . just one time I did see juping 1,4-1,5. The juping is the same time, when pulsating noise.

First time when I installed this turbo, car was quicker even with lower overboost.
But then the solenoid hose was disconnected from turbo and even then, max boost that I was getting were 1,4bar overboost max.
At the moment even with 2bar overboost, there isn' t so much torque.

Have anyone experience something like that?

[lynx]

hi again

I need help, because I don' t know what to do anymore.

The pulsating noise came back . . . yes, it went away for a few day, but now it' s back

Today I tested my car acceleration (ca. 170-180km/h). . . with S4 (c4) chipped . . . I let him go a little bit.

first time - mistake with 2 gear . . . I lost a big time, but I was able overtake him anyway.

second time - the pulsating noise came back I let him to go first . . . even then I could overtake him, but not so easy anymore.

When pulsating noise comes, then I lose power, that' s for sure. But where this noise come from, I don' t have a idea I checked all, nothing . . .

And one more thing. When pulsating noise are gone, then I have some other problem. 1-2 gear, everithing ok, but with 3 gear about 5500rpm and after that . . . power is gone. Rotations keeps to going, but there' s not that acceleration anymore . . .
What may cause this? Stock exhaust system? Cats only removed, but everything else is stock.

Anyway, some video too (sry for low connection speed):

http://www.friikartul.ee/lynx/

1.avi

1 gear, normal run . . . 2-4 gear, I was accelerating.
With 3 gear . . . power loss, high rpm, power gone

---

2.avi
1-2normal run. 3 gear I was accelerating.
When You hear carefully, then You could hear the pulsating noise.

Could anyone tell my, what causes this wierds things?

with best regards,

[4WheelDrifter]

Sorry Lynx. DV, BV, TBV are all the same thing, people use other different names too.

This sounds like a strange problem.
What MAF-Turbo pipe do you have? Is it a stock one maybe collapsing because of a pressure drop across the air-filter?
Maybe it's an exhaust manifold leak causing the noise and lack of boost.
But it seems strange that it goes away, then comes back.
Sorry I can't think of anything else at the moment.

[lynx]

Sorry Lynx. DV, BV, TBV are all the same thing, people use other different names too.

This sounds like a strange problem.
What MAF-Turbo pipe do you have? Is it a stock one maybe collapsing because of a pressure drop across the air-filter?
Maybe it's an exhaust manifold leak causing the noise and lack of boost.
But it seems strange that it goes away, then comes back.
Sorry I can't think of anything else at the moment.

I thought so . . I mean bypass .... I have allready two of them

I have custom pipe . . . because original is not good for turbo inlet. New have made from metal.

I think manifold is ok. I have heard leaking exhaust manifold, and mine seems to be ok.
Anyway, mystery seems to be continue . . . but I wont give up I will find this ... how I say it . . . problem

But, what else could be wrong?

with best regars,

[lynx]

I' m resolved one thing.

The pulsating noise was caused mainly form solenoid. I think, solenoid just tried to reduce boost desperately. Because software desinged to original k24 and 1bar overboost.

I just disconnected it and . . . car going even more better and there isn' t that noise anymore . . . all most. I have much boost in the middle range 3500-5000rpm. With 2 gear it' s all most normal, but with 5 gear @100km/h and gas pedal down . . . to much boost and turbo is surge . . . and then a bit surging noise, all most the same like the pulsating noise.
Anyway . . . at the moment I' m thinking how to reduce boost at the middle range . . . Could anyone suggest something?

And one more thing . . . with 3-5 gear, I don' t have a strong top end ... with 1-2 gear all ok, but with 3 gear and up, I loose power in top end. I mean 5000/5500 till end. Could original exhaust system cause that?

with best regards,