Boost peaking @ 0.55bar

[phaetonv10]

Hey guys

As the topic says, my 1.6 gtd peaks at 0.55bar.

At first I thought its the blow off valve, so I blocked it, plugged the top of the blow off. No difference.

Still peaks at 0.55bar. The only difference it has made is, before I plugged the blow off, I lost boost in pulses when in 3rd gear. But now when the revs peak in first, I suddenly lose boost, from 0.55 to 0.3 bar.

I am thinking a wastegate stuck open.

Suggestions???

[CrazyAndy]

Sounds like you MIGHT have a concern with your wastegate, that is if you are sure you don't have any cracks in the intake boot, or the boost feed line to the wastegate itself.  Is the atmosphere bleed on the other side of the WG diaphragm free and not plugged up?  Also is there any shaft play, and does the rotating assembly spin freely?

The only way I could think for testing, beyond visually confirming a stuck wastegate, is applying pressure to the wastegate diaphragm and feeling the atmosphere bleed for any air motion.  You could put the bleed hose end in a glass of water and see how much air comes out when you apply pressure to the diaphragm.  A little air starting off and then none would mean the diaphragm is moving at least some.  No or almost no air would mean the wastegate valve is stuck, and a lot of air continuously would mean you have a rupture in the wastegate diaphragm.  Again this assumes the problem is limited only to the wastegate and not the other components.

[bajacalal]

0.55 bar is 8 PSI, which I think 9 psi is around the normal amount of peak boost unless you modify the wastegate. That thing on the manifold, I believe it opens at 15 psi (1 bar) but the wastegate is supposed to open at even less. But as mentioned a boost leak shouldn't be ruled out especially if you are "losing" boost under acceleration.

[phaetonv10]

Sounds like you MIGHT have a concern with your wastegate, that is if you are sure you don't have any cracks in the intake boot, or the boost feed line to the wastegate itself.  Is the atmosphere bleed on the other side of the WG diaphragm free and not plugged up?  Also is there any shaft play, and does the rotating assembly spin freely?

The only way I could think for testing, beyond visually confirming a stuck wastegate, is applying pressure to the wastegate diaphragm and feeling the atmosphere bleed for any air motion.  You could put the bleed hose end in a glass of water and see how much air comes out when you apply pressure to the diaphragm.  A little air starting off and then none would mean the diaphragm is moving at least some.  No or almost no air would mean the wastegate valve is stuck, and a lot of air continuously would mean you have a rupture in the wastegate diaphragm.  Again this assumes the problem is limited only to the wastegate and not the other components.

I am pretty sure the intake boot is 100%, and the boost feed line to the wastegate looks new. Overall the turbo is in good shape. Never been fettled with.

The atmosphere bleed valve that you talk about , I don't exactly know what we are talking about.
Could you kindly elaborate?!?!

Btw my engine is a SB, and turbo is the kkk k14, water-cooled type.

[phaetonv10]

And I ve also checked and rechecked the whole IC circuit too. No leaks there too.

And I just lose boost in first gear. Not in second, or third.
When the revs peak in first, I the boost drops, but not in second. I pushed it pretty hard in 2nd to make sure.

[bbob203]

I think you out to put a manual boost controller on there you can use and air compressor regulator.

[phaetonv10]

I need some expert advice on this.

My conclusion is that my wastegate was stuck open. So after reading a lot of threads on sticky wastegates, I decided to slam it shut.

 I started by tightening the adjustment screw a bit. And boost increased from 0.55 to 0.65bar. So I tightened it some more and eventually stopped when boost reached 1bar.

And I am still running 1 bar.

My BIG question.
IS IT OK TO CONTINUE RUNNING 1 BAR WITH A STUCK OPEN WASTEGATE???
OR SHOULD I BE VENTURING TO UNDO THE WASTEGATE AND TRY TO CLEAN IT SO IT STARTS WORKING PROPERLY??

I was thinking I ll continue to run it as is. But a friend is adamant that I fix it up because its bad for the turbo. According to him I am reducing the turbos life. I am making the turbo do extra work than it would normally be doing with a working wastegate to make 1 bar of boost.
It makes logical sense, but I thought I would get a second opinion.

All help shall be highly appreciated.

[RabbitJockey]

what makes you think that its not working?

if the wastegate is stuck open it won't damage the turbo, quite the opposite sicne the turbo will hardly be doing anything it will not wear it at all

[phaetonv10]

what makes you think that its not working?

if the wastegate is stuck open it won't damage the turbo, quite the opposite sicne the turbo will hardly be doing anything it will not wear it at all

I thought that if the wastegate is stuck open, the turbo is revving more than it has to make 1bar of boost.

Under normal operation, the turbo would rev to say X to make 1bar and then to prevent over boost, it would let the extra exhaust gases vent through the wastegate and continue to rev at X. But with a stuck open wastegate, exhaust gases are constantly being vented along with spooling the turbo. So, I thought, to reach 1bar the turbo has to rev much higher.

Am I wrong in saying that?

[bbob203]

What was your boost at before this problem?

[RabbitJockey]

what makes you think that its not working?

if the wastegate is stuck open it won't damage the turbo, quite the opposite sicne the turbo will hardly be doing anything it will not wear it at all

I thought that if the wastegate is stuck open, the turbo is revving more than it has to make 1bar of boost.

Under normal operation, the turbo would rev to say X to make 1bar and then to prevent over boost, it would let the extra exhaust gases vent through the wastegate and continue to rev at X. But with a stuck open wastegate, exhaust gases are constantly being vented along with spooling the turbo. So, I thought, to reach 1bar the turbo has to rev much higher.

Am I wrong in saying that?

yeah, the wastegate is letting air bypass the turbine, so not enough exhaust flow is going to the turbo to let it spool up, so the turbo is actually doing less work because its not even getting the flow that would make it spin in the first place.

[phaetonv10]

So what you are saying is its ok to continue running it like this!?!?!?
I am not running the risk of ruining the turbo in a few days??

[phaetonv10]

What was your boost at before this problem?

Boost was peaking at 0.55bar. At first I thought it was the blow off, so I blocked it to no effect.

Then I got working on the wastegate.

[RabbitJockey]

yeah its not terribly bad to keep driving it like that.  u can probably just run that set screw on the wastegate tight and it should hold the wastegate completely shut which isn't really bad either as long as u don't end up with way too much boost.  it would be bad to keep driving with a boost leak, for example letting the bov open constantly because it over spins the turbo.

[phaetonv10]

Yea. Makes sense.

Is there anyway of getting my hands on to the wastegate valve so I can make it move by hand??