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-   -   Still no boost... (http://www.toyota-supra.info/forums/mkiii-supra/7471-still-no-boost.html)

drmmr15 02-03-2007 05:15 AM

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 02-04-2007 09:25 PM

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.

drmmr15 02-05-2007 07:00 AM

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.

drmmr15 02-08-2007 02:07 AM

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:

drmmr15 02-08-2007 02:15 AM

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.

OmeGa 02-08-2007 03:00 AM

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.

drmmr15 02-08-2007 03:29 AM

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.

IHateHacks 02-08-2007 03:37 AM

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.

drmmr15 02-08-2007 04:25 AM

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?

Supra2NR 02-08-2007 04:39 AM

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


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