I have an 88 TII. Car's been running perfectly.
Just last night, I was finally able to push it a little bit to see how it does. Well, since I still haven't been able to wire up my boost gauge, I'm just going by the stock one. Yes it works.

Well, first gear, it's nearly to the top all through the pull, 2nd gear, however, it starts up there, then drastically drops suddenly. I couldn't feel the boost, and I heard the motor running pretty much on it's own (no hissing). Shift into third, instant difference, boost is right back up, and the car pulls hard. Same with fourth, all the way into fifth.

What would be the possible causes for this? I have some ideas on where to start, but I wanted to get some input before jumping in and tearing things apart.
Any feedback will be much appreciated.

 

First of all, get that aftermarket gauge installed. Second of all, the stock turbo won't hold much boost to redline anyway. Expect it to drop off.

Third of all, you need to check for boost leaks. http://www.boostpro.net/prodtester.html Use this with a reducer (2 1/4" ?) connected to the turbo inlet. you don't need an expensive air compressor for this.

 

Awesome stuff. Thank you for that