Got Car Tuned - Was All Good But Now Its Making A Horrible Noise

[JustinP]

Got my PFC tuned in my R34 tuned the other day. When I picked it up (from XSpeed in WA) they had found that it was making best power at 14psi and had set it to that! I though the turbo would have been running out of efficiency at about 12psi or so higher in the rev range? Boost obviously did taper off higher in the rev range but they said to leave it at that.

I told them I didnt think it would be safe to run the turbo at that boost all the time, but they assured me it was!!?

Anyway I was very happy with the perfomance (was making about 203rwkw) with a very good power curve but I decided that I would turn down the boost a bit (to 12 to 13 max, with 10-11 for everyday use) but before I turned it down I let my dad take it for a spin. He was quite impressed I did notice though on the hand controller that boost did actually hit 1.05kg/cm2 at one point though

Anyway the next day I turned down the boost to about 11psi and I was driving it off boost for the whole day (testing to see how good I could get the fuel economy). Today I pushed it again and now it seems to make a wierd noise exactly at about 5500RPM. Seems to be coming from the drivers side, I think. It sounds a bit like when you let the air out a balloon when your squeezing the hole bit with your fingers, and only starts at about 5500RPM and get louder as the revs rise. It doesn't seem to be loosing any power but I have not really tested that as I don't like pushing it with that noise.

I visually checked any hoses that carry any pressure best I could and couldn't see anything that would be obvioulsy leaking. Does anyone have any idea on what it might be?

Edited April 5, 2007 by JustinP

[23PSI]

Do you have a t-piece for a boost gauge? check that - mine has split a couple of times and makes a high pitch squeel when it does - but i do notice a drop in boost pressure when that happens. maybe check intake manifold aswell? Not really sure what it could be.

[23PSI]

Take it back to the workshop that did the work

[nuffsaid]

Someone here is bound to say that if your tuner thinks 14psi on a R34 turbo is okay, then you should find a different tuner. Many guys on here have had theirs blow at 10/11/12 psi when pushed so I would be cautious. What yuo have done by turning the boost down is right.

Maybe there is an air leak, turbo gasket problem, have you checked that?

[mad082]

i ran my 33 on 14psi for about 8 months, turbo was still going. they do seem to go a lot better at 14psi than 11 or 12, contrary to popular belief.

sure they may last a shorter period of time, but they may not. if people have had thiers blow at 10 or 11 then shouldn't everyone just run it at 7psi to be safe? the ones that blow at low boost have probably spent a lot of time at redline (doing burnouts, etc), by a previous owner, etc. because that its really what kills a turbo, running big boost and then holding it high in the rpm.

[JustinP]

Do you have a t-piece for a boost gauge? check that - mine has split a couple of times and makes a high pitch squeel when it does - but i do notice a drop in boost pressure when that happens. maybe check intake manifold aswell? Not really sure what it could be.

That was my first thought being on that side of the car. I visually checked it all and couldn't see anything but I might pull all the hoses off and check them properly.

There is no engine problem either in the bottom end or the head that would ever make a sound like that is there? I couldn't imagine that being possible but it's my biggest fear killing the engine when it's only got 70,000k's on it I won't mind if the turbo goes eventually, I will just replace it with a GCG highflow

[JustinP]

Someone here is bound to say that if your tuner thinks 14psi on a R34 turbo is okay, then you should find a different tuner. Many guys on here have had theirs blow at 10/11/12 psi when pushed so I would be cautious. What yuo have done by turning the boost down is right.

Maybe there is an air leak, turbo gasket problem, have you checked that?

Yes I was very suprised when they said that. And its a pretty large / professional workshop... I don;t think I will use them again. The general service they gave me and didn't really involve me in any of the tuning process, just kinda took the gave it back I should have gone to Top Racing like I was thinking of initially.

I do have a big leak where the dump connects to the back of the turbo due to a snapped bolt, but I have had that for a while and that makes a completly different noise.

As long as I know the engine itself or even the turbo couldnt make that kind of a noise I will be happy as at least I know serious damage is not imminent.

Thanks guy for your input too

[JustinP]

i ran my 33 on 14psi for about 8 months, turbo was still going. they do seem to go a lot better at 14psi than 11 or 12, contrary to popular belief.

sure they may last a shorter period of time, but they may not. if people have had thiers blow at 10 or 11 then shouldn't everyone just run it at 7psi to be safe? the ones that blow at low boost have probably spent a lot of time at redline (doing burnouts, etc), by a previous owner, etc. because that its really what kills a turbo, running big boost and then holding it high in the rpm.

Yer I am suprised how hard it goes at 14psi compared to 12psi on the stock turbo. Maybe I will run it at 13 most of the time. I would not be too bothere if the turbo died in a year or so as then I can upgrade. I just don't want an exploding turbo to kill my motor too!

[mad082]

I just don't want an exploding turbo to kill my motor too!

yeah thats the only bad bit.

[JustinP]

yeah thats the only bad bit.

What are the chances of this actually happening anyway? Has anyone here ever experienced an exploding ceramic exhaust wheel sending dust and crap back up into the engine which has caused engine damage? I know it certainly happens (even though i find it hard to believe stuff could get back up there with the amount of gas being pushed out), but is it like a one in hundred chance or is it actually common when a ceramic turbo lets go?

[mad082]

its not the exhaust side, its the compressor side starting to wobble and then sending fragments into the motor.

have a chat to justin911. he had his let go at the drags and a piece of the compressor wheel get wedged in the butterfly and it was reving its arse off without touching the accelerator.

[JustinP]

its not the exhaust side, its the compressor side starting to wobble and then sending fragments into the motor.

have a chat to justin911. he had his let go at the drags and a piece of the compressor wheel get wedged in the butterfly and it was reving its arse off without touching the accelerator.

That makes more sence. Although I wonder if the nylon compressor wheel on an R34 turbo would reduce the chance of this over a steel wheeled 33 compressor wheel?

[RANDY]

I think the idea of a steel exhaust wheel is that they can take more heat and spin faster without shattering like a ceramic wheel would. Dunno about the nylon compressor ones, but i'd GUESS that a steel compressor wheel is stronger than nylon?

I've always beleived that the nylon wheels only let go when the rear ceramic wheel breaks. (shaft unbalances and the nylon fins hit the inside of the turbo). 33 and 34 turbo's still have ceramic rear wheels (I think? Definately the 33's do), and I think that is where your main worry should be. Too much heat and too fast RPM for the rear ceramic wheel will make it break... THEN your front nylon wheel will thrash around until it breaks, and sends plastic through your cooler and into your intake manifold... and so on.

[paulr33]

id say ratio of compressor dying to exhaust wheel dying would be 10:1

most common is the exhaust wheel dying, ive only ever seen one compressor die and that was justins

[1400r]

"Today I pushed it again and now it seems to make a wierd noise exactly at about 5500RPM. Seems to be coming from the drivers side, I think. It sounds a bit like when you let the air out a balloon when your squeezing the hole bit with your fingers, and only starts at about 5500RPM and get louder as the revs rise"

thats the strangest explanation detonation Ive ever heard

what was the knock reading?

either that or your getting some comp surge ?

Edited April 5, 2007 by 1400r

[JustinP]

"Today I pushed it again and now it seems to make a wierd noise exactly at about 5500RPM. Seems to be coming from the drivers side, I think. It sounds a bit like when you let the air out a balloon when your squeezing the hole bit with your fingers, and only starts at about 5500RPM and get louder as the revs rise"

thats the strangest explanation detonation Ive ever heard

what was the knock reading?

either that or your getting some comp surge ?

That was the only way I could explain the sound, it's a strange noise. Actually it also sounds a bit like a belt slipping, but it's definately ait escaping somewhere. Also I noticed last night it does seem to loose some power when the noise starts. It wasn't detonation. Knock reading was below 40.

[Devils_Advocate21]

Could it be that air from inlet manifold leaking around gasket or vac leak ??