Still no boost...

[flight doc89]

Originally Posted by drmmr15

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.

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.

[Kuban]

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.

[drmmr15]

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.

[flight doc89]

Originally Posted by drmmr15

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?

[kwnate]

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.

[Supra2NR]

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

[drmmr15]

Well, I forgot to mention there was no power when I drove the car. The turbo wasnt spooling before. Now that the exhaust is disconnected, I can hear the turbo spool, but get no boost read from the guage. I dont wanna drive it with the exhaust disconnected, so Im going to take my car to an exhaust shop and have him fix the terrible job the previous owner did on the custom exhaust. He welded everything in, and I think the cat is clogged, Imma get a new cat and have the shop do some rewelding on the downpipe. I would get an aftermarket exhaust, but I will eventually sell this car (another story). I just wanna get it running right. Plus Ive never driven anything with more than 120HP, so I want boost So i think the backpressure from the bad exhaust system was causing the boost to only reach 1psi max. When the exhaust is unhooked, I can hear the turbo spool nicely, but that guage reads -4psi. So my problem is the exhaust, I think. Im not sure, so thats why it'd be nice to have someone come look at it. Thanks kwnate. Im pretty sure you would know a helluva lot more than I do, so we should try to set up a meeting. Next weekend Im pretty swamped. But maybe next Sunday afternoon? PM me. Thanks everyone for their replies.

Edit - Ill try blowing through the BOV tomorrow. Thanks.

[Kuban]

Keep in mind, in neutral or in park (wether u have auto or 5spd) you wont boost, the engine will pop the wastegate at a very low psi to keep it from overspooling. And the backpressure from the exhaust would indefinately hold your spool abit.