1989 MK3 Turbo (Driveability Issues)

[polarbear]

Hey guys, first post on this forum, I am a newly minted supra owner, just looking for a little guidance. Car is a 1989 Turbo, 7mgte, 5spd manual trans. Once in a while it feels like I am having boost issues. Start the car, no check engine light, everything feels good, then you drive it, as soon as you hit a little boost, the CEL comes on and stays on, and the car feels slow as hell, it sounds like the boost is just dumping off from somewhere, but my boost gauge still reads that the turbo is making pressure. So i checked all my intercooler piping, had a broken hose and repaired that, and the problem is still there. But i let the car warm up and parked it, turned it off, then turned it back on a few mins later and it was fine, the CEL stayed off and it turned into a rocket, fast as hell. But recently the CEL always comes on and stays on, anyone else have this problem? Feel free to talk in technical terms, I'm an auto tech, so I have all the resources to fix or check this thing, just not too much time and not entirely familiar with these cars. I am aware fuel cut is a big issue, but to me it does not feel like fuel cut. I was thinking maybe boost sensor or MAF? checked all the "obvious" stuff like vacuum and ic piping/leaks.

Please help! Lol i feel like a newbie at this stuff again. I just dont have the time to look thru the car for hours on end, I need to get pointed in the right direction, but if i have to spend time and scope it all out, I will. Just wondering if this was a common problem and if anyone else has had this happen? Thanks a lot!

[bioskyline]

what hose was broken??? its possible your turbo may be shot. i blew the lower hose from turbo the the ic, and the turbo over span and fragged the blades. take off the intake pipe from the maf to the turbo and look inside, see if there appears to be any damage.

[polarbear]

yeah turbo is okay internally. it does make boost, just seems like its not ever reaching the intake manifold correctly, and the "boost hiss" is louder when the CEL is on, as if the charged air were leaking out somewhere, im thinking maybe an issue with the blowoff valve? otherwise i have no friggin idea.