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

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.

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.

That helps a lot. Sounds like its the exhaust system. Im getting a Cat off an '89 turbo that had 90,000 miles for $20 and taking it to an exhaust shop to fix things. lets hope this works out. :x: Thanks.

HELL YES!!!!! Well, today, I fixed the timing of the car, and i revved the car up a bit (exhaust still unhooked from the O2 housing back) and I heard the turbo spool up and the once i let off i heard the BOV. It sounded sweet, but the boost guage still sat at -4psi. I said screw it, and decided to drive the car around the block with the exhaust off to see if it worked. :eek: HOLY S***!!! The turbo kicked in hard and broke the tires loose in 2nd. I had no idea how amazing boosting was. SO i know there is no boost leak, and my turbo guage is bad. I am going to hook the exhaust back up and see if it works fine. If not, Ill keep going to forward with what I had planned, and that is to have an exhaust shop do some rewelding on the downpipe, and put in a new cat. Thanks you all for your advice, and am happy to be part of the boost addiction......FINALLY!!! :bouncy:

Also. Im such a genius that i forgot to put a heat shield back on the exhaust manifold right under the turbo. My question is, can i leave it off, or will it melt things if I dont? The reason i dont wanna do it, is i would have to take the whole turbo assembly back off to get it on there...and that sux...
Thanks.

I dont have mine on, it gets in the way of things IMO. Also the stock boost gauge is garbage, mine reads -4 when im around 5 lbs then it jumps to +8 instantaniously.

Yea, people were telling me the stock boost guage was horrible. Whats a good aftermarket one? Plus, is the GReddy profec-B or whatever its called a good boost controller? I want to run 10psi on stock everything except i have a 3 inch exhaust and a cold air intake. I wont do that until I give the car a good tune-up, put in synthetic oil, and check/change all the fluids though. Would that work, or would I run into problems at 10psi? Thanks for the info.

Edit - Also, what octane do you guys use for gas? I just got this car running, and want to use good gas. Thanks.

Whatever aftermarket boost gauge you get, make sure its mechanical, not electric. Which means you have to run a vacuum line directly to the gauge. There is no sending unit like an electric gauge uses (like the stock one). It will state whether its mechanical or electric right on the box. That's funny I must like repeating myself, or I must like talking to walls. You can buy a $200 electric boost gauge but a $10 mechanical one will be more accurate.

I'm going to go out on a limb and say, your stock 100,000 mile head gasket will not last very long on 10psi. Then again, a stock 100,000 mile head gasket won't last very long on 7psi.

Thank you. You have been very helpful to me on all my posts. I have a JDM engine in my car with, Im assuming, less than 60,000 miles on it, and a new head gasket was installed before the motor was installed. I dont want to get a metal head gasket (selling car soon, like before summer), but should I re-torque the one I have in there? This car will not be a dialy driver, more like a weekend car. If going to 10psi on a new stock head gasket that is re-torqued is a bad idea, then I wont do it. Once again, thank you for your input, and sorry for making you repeat yourself.

Edit - Oh, and where can I find a cheap, reliable manual boost guage?

Why don't you jus get a manual boost gauge
Its a pretty simple install
Drill a hole in the firewall
Put the hose thru
Connect the hose
Power the gauge
Its hard if you dunt know what your doing
But it was pretty simple, that's why I was kickin myself on the head, cuz I ddnt figure it out

And ps
Manual is the way to go its cheaper and its more accurate
And autometer is still the way to go

Gauge about 50 bucks
Wires(if u dnt have any laying around)
About 3 bucks
And the mounting cup is about 20 bucks
It'll be a pretty good investment