I have a problem right now with a serious lack of boost. After driving it hard (and a small possibility of a boost spike that resulted in some serious a$$-swervin power) I have to rev it hard just to create 0 boost. The major sympton is around 3K where boost would normally start building, I get a WOOOOO sound.

Its a '93, Single T60 Turbo, HKS External Wastegate. According to the FC Commander I get just over 400 mm/HG vacuum, timing is mostly advanced @ 28 degrees, EGT's @ 1200, can't think of anything else halfway pertinent.

I've searched here and asked around and gotten a few common problems to address:

1. Wastegate stuck open
2. Serious leak along the intake tract
3. Vacuum problem.

I can understand you guys might not be able to tell the exact problem so I'll narrow the questions:

1. I think the WOOOO sound is the key. What do you believe it to be? Air escaping through wastegate or intake tract? Turbo itself?
2. How do you fix a stuck wastegate? If I have to take it apart what am I looking for?
3. How do you diagnose a boost leak if I have to put load on the drivetrain to create boost?

If you can help me with any of the questions or just point me to where someone else already answered this, I'd appreciate it.

 

The easiest and cheapest to fix, and the most common problem causing zero boost is a torn boost coupler. The whooooo sound is probably the boost pressure leaking out of it. You may have to completely remove them to find a tear - it's not always obvious.

 

I guess my first action is to completely disassemble the entire intake tract and carefully inspect each coupling.

 

An easy way of spotting boost leaks.... is using smoke!!!

Make sure the engine fan is shut off, by shutting off the A/C if present. Get the engine running, and get a proper sigar or cigarette. Get it lit, and blow the smoke under the hood. Or ask a chain smoker....

Since this smoke is very "light" is really is good to source small boost leaks, even small cracks in hosing, or intercooler....

It even shows vacuum leaks.....

 

How about smoke from Mary Jane? As long as it doesn't take more than 3 bowls, I think I could spot the leak!

 

I firmly believe in this method. Smoke traces and stuff are easily destroyed by your radiator fans, and can be hard to see in dark spots.

Get your couplers out of the engine bay and into good clear light, turn them inside out, stretch the material to look for cracks. If it's there you'll find it. It's straightforward and doesn't take long at all.

Dave