Can't figure out boost problem

[VaB90gsx]

I'll start with a description of my problem then list everything I've changed / replaced.

I have a 1990 gsx. The car idles fine and actually runs great. The problem is boost is inconsistant. By this I mean that sometimes the car will build boost and other times it won't. When it doesn't make boost there is a very loud medium pitch whine. It sounds a little like the first part of a police siren. If I go WOT my boost gauge sits at 0 the entire time. Sometimes though, I can build boost just fine and the car runs great. Holds boost throughout the entire gear.

This is what I've done

-boost leak test, fixed all leaks.
-replaced throttle body
-replaced intake manifold with smim
-changed all vacuum lines while doing the intake manifold
-put t-bolt clamps on all couplers
-put clamps on all vacuum lines
-checked all piping for holes / leaks
-swapped MAF's and filter
-swapped wastegates
-replaced elbow gaskets / tb gaskets / IM gasket / valvecover gasket
-new plugs / wires

There's also an oil leak I can't seem to find. I'm thinking it's coming from the oil pan though since the front of the motor is all dry. Oil drips onto the downpipe and near the driveshaft. When I pulled my old intake manifold there was a little bit of oil on the back of the block, but I couldn't find any definitive signs of oil leaking from somewhere.

What else could be the culprit of this erratic boosting problem?

 

[GVR4592]

Did you check the turbo for shaft play? That could be the whining sound you are hearing. Turbo's get a little nosiy when they start to fail.

 

[VaB90gsx]

Did you check the turbo for shaft play? That could be the whining sound you are hearing. Turbo's get a little nosiy when they start to fail.

Yes, forgot to mention that. The turbo has some shaft play but I can't actually get it to hit the housing. This was my conclusion also, but I don't feel like spending money where it's not needed. Is there any other possible culprit to the problem? Thanks for the reply

 

[oldman]

-boost leak test, fixed all leaks.

Not to doubt you but I have heard this one too many times, what were the detailed results of your leak test?

Yes, forgot to mention that. The turbo has some shaft play but I can't actually get it to hit the housing. This was my conclusion also, but I don't feel like spending money where it's not needed.

That says nothing about the hot side, you need to make sure the turbine is still fully intact. Was it in/out or side to side shaft play?

There's also an oil leak I can't seem to find. I'm thinking it's coming from the oil pan though since the front of the motor is all dry. Oil drips onto the downpipe and near the driveshaft. When I pulled my old intake manifold there was a little bit of oil on the back of the block, but I couldn't find any definitive signs of oil leaking from somewhere.

Power steering or your transfer case.

What else could be the culprit of this erratic boosting problem?

Like GVR, I suspect the turbo but it wouldn't hurt to check compression and exhaust leaks.

 

[VaB90gsx]

Not to doubt you but I have heard this one too many times, what were the detailed results of your leak test?


That says nothing about the hot side, you need to make sure the turbine is still fully intact. Was it in/out or side to side shaft play?


Power steering or your transfer case.


Like GVR, I suspect the turbo but it wouldn't hurt to check compression and exhaust leaks.

I replaced two couplers, the gasket on the elbow of the turbo, new throttle body w/ gaskets on both sides and put a few clamps on some vacuum lines. We then did another boost leak test and had the pump set on 20 psi for 4 - 5 minutes and the entire time both boost gauges read 20 psi. (autometer gauge on a-pillar and greddy profec B)

It was side to side shaft play. Couldn't really move it in and out at all.

I don't have power steering anymore. I'm losing engine oil. Probably about a quart every 500 miles.

The entire exhaust probably has 1k miles on it. Brand new 2 1/2 in downpipe to 3 inch with a bracket on the end going to the cat. A brand new gasket on both sides of the cat, with all fresh piping after the cat. Also all new hangers welded up with new rubber inserts all the way down.

 

[VaB90gsx]

I'm going to check out a turbo on Monday, but I really don't want to buy it if it won't fix the problem. Does anyone have any ideals at all to anything else that could be causing this problem? Need replies today so I can go over the car to check the suggestions out.

To the mods: if this is considered a bump I apologize, and you can lock / delete thread.