No boost!

[Nitrobasher]

Recently picked up this 91 GVR4 from TN. I was aware of the no boost issue when I bought it.

The low down on the car

Has Some sort of FP turbo with minimal shaft play, however the intake fins are pretty beat up, the exhaust side looks and feels fine.
GM Maf
v3 Link
38mm Tial Wastegate

I figured the car was loosing boost pressure somewhere before the GM Maf because the car pulled fine throughout the RPM band, just obviously with no boost. I got around to installing an AEM digital Boost gauge and confirmed that no boost was being made.

I eliminated most of the stock emissions and unnecessary vacuum and double checked all the lines for leaks. Found nothing. I also removed the boost solenoid and a few other connectors related to stock vacuum routing... This wouldn't trick the computer into thinking somethings off and preventing boost correct???

I pulled the wastegate off to verify it was still in working order, I thought the sealing ring might be missing or bent, however everything seemed to check out fine. I then found a bad bend/leak in the stock intercooler

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Figuring this was the problem I installed a new FMIC. Took the car for a spin and logged a pull. I found that by 4500 rpms I can barely build 2psi of boost and my knock count is through the roof. By WOT I'm at 15.1 counts of knock and down to 8.9' of timing.
Unfortunately I have not been able to pick up a Wideband yet so I can not verify AFR. I can't help but think this has something to do with my low/laggy boost.

I did a compression test just to ease my mind numbers came up from first to fourth
145 150 150 160

I've checked and double checked for boost leaks. Found very little, nothing enough to cause this issue anyway. I've verified there are no pre turbo exhaust leaks. I haven't checked the exhaust for blockage but it is coming out of the tailpipe strong so I doubt that is the issue.

Sorry if this is a confusing post. I'm trying to get as much information in as possible. Thanks

 

[Dsmkauai]

K best idea stop driving the car ASAP, if you keep pushing it and have high knock your going to melt something eventually. Sounds like your turbo is shot bro, you need to check for in and out as well as up and down shaft play. If there is damage to the compressor wheel than something either got sucked in or the turbo failed. It's only a mater of time before something worse happens. Is there any noise when you try to make boost?

 

[Nitrobasher]

K best idea stop driving the car ASAP, if you keep pushing it and have high knock your going to melt something eventually. Sounds like your turbo is shot bro, you need to check for in and out as well as up and down shaft play. If there is damage to the compressor wheel than something either got sucked in or the turbo failed. It's only a mater of time before something worse happens. Is there any noise when you try to make boost?

Not much abnormal noise. There is a small amount of in out and up and down shaft play in the turbo, Like I said it seems to be in Okay condition, however its not pushing any oil past the seals and the turbine seems to spin fairly well. Heres a pic of the intake side though.

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I also noticed that my IAT is stuck at 77' throughout the entire drive cycle maybe has something to do with the knock?

If it has a Flex pipe section -check it..I have had several collapse internally..Car will run okay just will not build boost...Looks perfectly fine on outside But.....

Restricted down to smaller than a quater on inside...

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I'll double check, thanks for the advice.

 

[combs-dsm]

See if it is the turbo and it haven bent up fens. See if a buddy has an extra 1 to throw on and if your able to bhild bkost after that. Your problems isnt rare. Ive had the same one before on my 92 but wasnt able to get as much info and took a long shot, changed out the turbo and it was like night and day.

 

[VRP]

If it has a Flex pipe section -check it..I have had several collapse internally..Car will run okay just will not build boost...Looks perfectly fine on outside But.....

Restricted down to smaller than a quater on inside...

You must be logged in to view this image or video.

 

[Dsmkauai]

Dang bro something got sucked through that turbo! I'd be concerned with that much damage, and also where the pieces are that did it.

 

[SpryTSI]

is your wastegate functioning properly? I hit mine with some compressed air to make sure the arm and wastegate was operating.

Also, on my 92' GVR4 my CAT fell apart into itself and clogged the exhaust flow. Try dropping the CAT out and driving around the block on just the downpipe.

 

[Boosted187]

Any update?

 

[Nitrobasher]

Any update?

I was able to pull the exhaust from the o2 housing today, went for a test drive and still the same deal. 15' of knock with no more than 1 or 2 lbs of boost.

I've verified the wastegate is sealed, the fmic and intercooler piping is all brand new. I removed the turbo and will take it into the shop tomorrow to look over.

I got the p/s and alternator belt reinstalled though so making small headway .