Still no boost...
 

So, I bought my 87 Supra Turbo for cheap ($1000) because the turbo wasnt spooling. I figured it'd be an easy fix. I pulled the turbo, checked for cracks, leaks, etc...and nothing. The turbo spins freely and no shaft play. Before I pulled the turbo, when I drove the car, there was a hissing coming from the turbo area like a leak somewhere. I figured it to be an exhaust leak. So when I put the turbo back on, I kept the downpipe unhooked and started up the car. The hissing was gone, but still no boost. I havent thouroghly inspected the IC piping yet, but that might be the problem. My question is, would an exhaust leak keep the turbo from spooling and give the car no power, or would that be a leak somewhere else? Also, if I had a vacuum leak, would the car die right away, or would it still run, but miss-fire terribly? I would really like to get in touch with a knowledgeable someone in the Seattle-Everett area and just have them come check my car out. As always, money is tight, and a helping hand would be greatly appreciated. Thanks.

im not, sure but have you checked the Blow off valve, maybe its stuck open or something. i'm not entirly sure, but worth a look at, its easy to get and they arnt too expencive.

What does the stock BOV look like? Is it the selenoid lookin thingy on that one BOV hose? Also, The sound was coming more from the downpipe area. I think I just might have a bad intercooler or hoses. But Ill check that. Thanks.

What makes you think you are making no boost? The stock gauge always reading -4? Why don't you hook up an aftermarket MECHANICAL boost gauge, not an electric one. Then take it from there.

my exhaust leak sounded like a choo-choo train, not a hiss.
is it not spooling, or just not boosting? when you get on it, do you hear the turbo spool but still no boost kick? if it's spooling but not boosting, check the BOV.

an exhaust leak would indefinately keep your turbo from spooling. Although only to a certain extent. You could have all kinds of leaks to keep you from spooling. I realistically could be spooling and you just have a real bad boost leak. Aka anywhere from the lower ic pipe to the upper ic pipe to the ic itself. Your bov could have a leak, intake manifold could be leaking aswell. Get urself a boost leak tester or make one.

I hear the turbo spooling, but the boost guage reads -4. I did not have boost when the exhaust was hooked up. Right now, I have the exhaust unhooked from the O2 housing back and I can hear the turbo spooling when I rev it up. I don't hear the leak anymore, but that could be because the exhaust is so damn loud. Im going to check the BOV, and my IC piping or the IC itself could be bad. The turbo is spooling but no boost showing up. I am afraid to drive the car with the exhaust unhooked. I am also going to check the vacuum hoses. Thanks for all the advice, I will hopefully solve this problem soon.

pop hood and look between the left strut cap (that's left wheel, not left looking from front) and the quarterpanel, there is a tiny little black box with vacuum hoses coming out of it. It should say something like boost sender unit or pressure sender or something like that. just follow the vacuum hoses from there and make sure they all plugged in good.

i know you said you ain't boostin, but try ignoring the guage. stomp the gas and see if all you power comes at once or does it take a second before it kicks you in the ass?

Your car won't build boost when there is no load, the turbo will still spin. This probably why you don't hear the noise with the downpipe disconnected. Its possible that your car is boosting and the gauge or sender is bad.

Inspect all your vacuum lines and Intercooler piping and let us know what you find. I might be able to take a look at it sometime next weekend.

no load, no boost
 

Maybe that's why you think your not boostin, bcuz your not boostin
You been revving it at nuetral or park
That's why there's no no boost
If the gauge reads at -4 but not moving at all
Its a bad sending unit
If its broken the boost gauge will be at 0 constantly
The hissing sound can be a bov problem
Have you tried blowing on the bov
If you can blow on it freely, that's most likely where you're problem lies