doabarrelroll

When I pulled the turbo originally, I checked both sides of the shaft and found them to be intact. Also, I had a turbo rebuilder inspect it and he confirmed that it was in good condition as well.

jc in rb

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Slow Project 951

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Slow Project 951

Still no boost , restriction removed. assuming my waste gate is stuck open. Was unable to see the restriction until the pipe was dissected . Could this be you issue as well ?

doabarrelroll

It could be, I took off all of my exhaust hardware to see if that was the problem particularly on the crossover pipe. I have the 3 piece version too so it's a bit easier to see inside it. What part of yours collapsed?

doabarrelroll

Also, did your turbo spool at all? What other symptoms did your car have? Based on what I hear from mine, it sounds like it can only spool so much, then it stops completely, staying at 0 Bar at WOT. I would think that if I had a collapsed pipe, it would spool up to like 1 or 2 psi.

Slow Project 951

This is the section between the turbo to the cat. As you can see the restriction was not evident until the pipe was cut open. The collapsed inner wall of the pipe was found at the bends. The cross over section supplies the turbo, this is the the section exiting the engine compartment just before the catalytic converter. I removed the cat as well, and put straight pipe all the way to the muffler.
This piece is expensive as $&#( . I was able to have a muffler shop fabricate it for me for a hundred dollars. I strongly urge you to look into this as apposed to spending more then a grand for a oem pipe. The site 944 online has a similar occurrence documented with photos as well.

Slow Project 951

I have approx 1 bar at wot. Had very little acceleration at all. After removal / replacement of the pipe I have a very slight improvement in acceleration. I agree that you should register some pressure on you gauges even without a load.
I have too reread the entire post , but I thought I recalled you hearing the turbo spin and noted no shaft play with removal ? I have yet to remove my turbo as it has been on for over 25 years and doubt it will come off without making me bleed and broaden my neighbors vocabulary. I am going to look at the waste gate next.
Have you hooked up a secondary gauge to verify boost pressure or are you relying upon the dash gauge?

doabarrelroll

My exhaust is stainless steel from the downpipe back so, I would be surprised if it collapsed, but, I'll check it anyway.

I have three gauges measuring boost pressure; the in-dash, my AVCR, and an external VDO gauge.

CyCloNe!

I'm curious in your findings.

doabarrelroll

After reading up on this a bit more, I think I'm going to pull the turbo again and get a second opinion. I have a sneaking suspicion it wasn't balanced properly or the bearings on it are too worn despite the rebuild.

Slow Project 951

I believe they are all stainless and the original are double walled. I am not sure the first exhaust from the turbo is double walled ? I know it is from the first flange out.
My muffler guy welded to the double wall and I am afraid I may still have restriction. I will attempt to cut and look again hopefully Thursday. Don't know if you can send a little camera down the exhaust after you get it apart yet again ? Do you have after market stainless or original ? Best of luck !
My big concern now is what caused my pipe to collapse ? Was told most likely rapid temp change such as hot pipe hit with water, however I have not been driving through puddles ? Could I be putting out way too much heat ?
Again not to steal your thread, Just sharing my thoughts as I babel and type.

doabarrelroll

I'm not sure, I'm happy to oblige anyone who is having a similar problem.

So, starting over, I'm looking to see if I missed anything...

A mechanical problem with the turbo (imbalanced, shredded compressor fins, etc)
A leak or other problem in the air intake system (either before or after turbo)
The wastegate sticking open (jammed open? warm dump pipe is a symptom)
A leak in the exhaust system (crossover, headers, etc or collapsed pipe)
Other mechanical problems (engine out of time, knock, etc)
Engine computer problems (KLR??? if the cycling valve is deleted, this shouldn't be an issue?)

If the engine can operate fine through the RPM range and runs as if it were a totally slow N/A, it would indicate that either there is a leak after the turbo, broken wastegate, or a broken turbo?

doabarrelroll

I've also noticed that all my intake hoses (after the turbo) are lightly covered in oil on the outside. I wonder what that may indicate?

CyCloNe!

Usually when I have found it on the outside it was a leak, crack in hose or loose connection some where. Always see some in the inside but on the outside it abnormal.