Wierd turbo sound....

[WFO731]

Well i just put an Evo3 16g on my car, got dsmlink in, all my fuel stuff finished and i start it up and idles fine. Takes off just normal everything sounds good and once i go under boost it sounds like i have a supercharger under the hood, just a really loud squeal. When i am under boost and go to shift there is no blow off, it just barely flutters down, also it will only build about 8-10 lbs.... all help would be greatly appreciated.

 

[xioca]

How much shaftplay does the turbo have? Sounds like it may be scraping against the housing causeing the noise.

 

[WFO731]

Turbo is brand new, took the intake off just now and checked anyways and there is no shaft play.

 

[xioca]

It could just be that it is a larger turbo than you are previously used to. As for only building 8-10psi you should check for boost leaks.

 

[WFO731]

Ya I am going to check for leaks tomorrow, and I have been in alot of dsm's that have 16g's and bigger so its not that im not used to it, its obviously not right because the squeal is so extremely loud. Would a boost leak cause there to be no blow off?

 

[xioca]

Are you running the stock blow off valve? Also check the BOV pressure nipple and make sure it's connected properly.

 

[WFO731]

Nipple is hooked up properly, someone else on another forum asked the same thing. and I am on a crushed 1g bov.

 

[xioca]

How crushed is it, does the nipple touch the bottom lip? It may be crushed to far, not allowing it to function properly.

 

[WFO731]

not quite, the first one worked properly on my 14b and then went i got this 16g it started, so i put another 1g bov and it does the same thing

 

[kenamond]

Are you sure you're getting oil to the turbo? A loud squeal sounds like a bad thing. My old T25 squealed when it was on its way out due to the compressor or turbine blades rubbing the housing. Not too familiar with the B16 oil return tube, but if you could pull it off and start the car (make a bit of a mess) just to insure that you're properly lubricating it.

Is the squeal super high pitch like a turbo or is it lower pitch? Is it a clean, whistle sound? Does it happen at low rpm (4k) and high rpm (6k) as long as you're full boost?

As for the BOV sound, it may be surging. You can test the BOV with a vaccuum tester to see what vaccuum opens it, and you can do a boost leak test to see if its holding boost without leaking past the valve. You might also want to pull the BOV vac line off the BOV while the car is idling and see if it's drawing air; it could be clogged.

Also, is your MBC (do you have one?) run to the BOV line or to the compressor outlet?

What else....

Maybe it's a REALLY bad boost leak that happens to whistle. Boost leak test is a good idea after changing any of the induction system.

 

[WFO731]

Some one else said i should check the oil feed line, i took it off while the car was off and it did begin to bleed out oil.

It is a super high squeal, like a super charger sound almost and it only does it as boost builds all the way till i let out, i just went out again and it built to 12 lbs.

And as for the the BOV, it was surging, and i will pull the vac line off tomorrow.

And yes i do have a MBC, it runs to the bov line.

 

[WFO731]

Checked the bov line, it is pulling in air.

 

[WFO731]

I pulled the oil return line and plenty of oil came out.

 

[kraka]

I don't think its a sign of a blown turbo...

After a few months of ownership, my EvoIII started making similar noises...I got scared and thought it was blown already...

Turns out I had a very bad boost leak, too much air was escaping at the throttle body elbow flange....

Boost leak test! This is your problem, I can basically guarantee it....Don't disagree until you try it!

-Josh

 

[WFO731]

I don't think its a sign of a blown turbo...

After a few months of ownership, my EvoIII started making similar noises...I got scared and thought it was blown already...

Turns out I had a very bad boost leak, too much air was escaping at the throttle body elbow flange....

Boost leak test! This is your problem, I can basically guarantee it....Don't disagree until you try it!

-Josh

Going to build one right now, about 75% of people think the same thing that it is a boost leak, I will let you know if this is the problem after i test it.

 

[spoolin90]

Well one thing you should not have is your mbc hooked up to the bov line. That could be were you are getting the problems with your bov not opening fully.

 

[WFO731]

Well one thing you should not have is your mbc hooked up to the bov line. That could be were you are getting the problems with your bov not opening fully.

That is where I was running it on my 14b for the last 7 months with no problems, why would it just start up now out of no where?

 

[kenamond]

That is where I was running it on my 14b for the last 7 months with no problems, why would it just start up now out of no where?

If you don't have a nipple on your J-pipe, you can add one. You'll get better boost control with signal from the compressor rather than the IM, and it won't affect BOV performance. You might want better boost control considering the potential for creep with your setup.

And since the turbo's officially on your car, you should update your profile.

 

[wvturbo2]

Boost leak can cause the bov not to release air, compressor surge, and possibly your squeling noise. Did break the turbo in ?

 

[Burnett03]

If you don't have a nipple on your J-pipe, you can add one. You'll get better boost control with signal from the compressor rather than the IM, and it won't affect BOV performance. You might want better boost control considering the potential for creep with your setup.

And since the turbo's officially on your car, you should update your profile.

i always heard it was the other way around.. the boost is more stable at the intake manifold than the turbo outlet.

 

[WFO731]

Boost leak can cause the bov not to release air, compressor surge, and possibly your squeling noise. Did break the turbo in ?

How long of a break in period does it need?

 

[xioca]

Pretty much just prime it before your start it up for the first time, and maybe take it easy for the first few hundred miles if you are that worried about it.

 

[fisherob]

Was it a boost leak?

 

[kenamond]

i always heard it was the other way around.. the boost is more stable at the intake manifold than the turbo outlet.

The boost controller is a closed loop feedback system. Having the signal you're trying to control (boost in the compressor outlet) closer to the controller (MBC) improves the response of the control system. "Wiring" to the BOV forces the signal to go from the compressor, through the intercooler and pipes, past the throttle plate, through the BOV vaccuum line, T, and other vac line to the MBC. Much longer than a 12" piece of tube straight from the compressor outlet and way more restrictions that change the signal.

It's like driving a car blindfolded via directions you get through voicemail and the directions are for a car in front of you...well not that bad, but you get the picture.

Also, if you're at 20% throttle on a hill, the pressure in the IM will be lower than in the UICP (throttle plate drops pressure - that's its purpose), so if you're controlling boost from the IM, the turbo may be WAY too high, out of its efficiency range, and maybe wearing itself out more quickly. And if you're trying to use your foot to keep boost down, you'll not be as effective, as you're not using turbo boost pressure to control the wastegate.

The counterpoint is that the turbo will be pre-spooled when you open the throttle up.

Either way, don't T it into the BOV line.

 

[kenamond]

Was it a boost leak?

It's a leak in the induction system. The turbo pressurizes everything between the compressor and the intake valves. If there's a leak anywhere in there, the boost pressure leaks out. This is a problem because the engine computer "counts" air molecules before the air gets to the turbo, so any of this measured air (that the computer thinks is going into the combustion chambers) that leaks out doesn't actually make it to the engine. The computer computes how much fuel is needed by looking at that air measurement. If less air is getting to the engine than what it measured, it injects too much fuel. You run rich. Rich robs power and fuel economy. Going slower and paying more at the pump is not as fun. There is A LOT more about this if you'd use the handy search feature.