Supra Problem

[MidNiteBlu 5.0]

Well guys I was gonna but this in the windsor power but it doesnt pertain to windsors lol. At school we have a Toyota Supra Turbo that was donated to us. It is the older design but im not sure what year it is. We are fixing it up and are gonna race it at the local 1/8th mile track. Well today it wont idle at all. It will go down to like 800 rpms almost die and then surges to like 2000 rpm and then back and repeats by itself. We just removed all the exhuast from the manifolds back. We tried resetting the computer but it does the same thing. I dont know what is happening so any help would be great!

Later

[BrooklynBrawler]

hey dude,
now im not usually helpin to solve jap problems , im just used to beattin them,........but if i must .........
well just think what would give u the same prob in ur 5.0!!!
any guesses........havin been that route winth both of my stangs , first thin i would look into r da sensors..........
run a code scan .....and c what it turns up
im not familiar with the heart of the supra.........but in my stang it was what is called the : either THROTTLE POSITION SENSOR
..........................................or....TH E MAP SENSOR
might also look into the os sensors..... but it deff wont be the exhust......good luck and if it works ...then REMEMBER::
***********IM NOT THE 1 WHO HELPED U SOLVE A SUPRA PROB

[MidNiteBlu 5.0]

I am thinking that it is the TPS but i am not sure where it is on that damn JAP car!! I told my teacher that we should get a carberated muscle car but all the money for this project is being donated so i guess we are gonna stick with it. Any more suggestions?

Later

[PKRWUD]

It needs an AMERICAN rubber band to replace that dinky japanese one. The hamster is probably hungry, too (you did say it was a turbo, right?).

Seriously, the TPS won't effect the idle, by itself. It will effect the throttle response at idle, but if the engine is just sitting there idling, a bad TPS won't have any effect. I would look at the O2 sensors, as well as a hard core search for a vacuum leak. A surging idle is almost always caused by unmetered air entering the mix.

Take care,
-Chris

[MidNiteBlu 5.0]

It needs an AMERICAN rubber band to replace that dinky japanese one. The hamster is probably hungry, too (you did say it was a turbo, right?).

Bawahahahahahahahahahahaha LMFAO. Yea i know many of my friends have told my teacher that we should start with a muscle car but he seems intent to use this one (probably because it was free) LOL. Oddly enough the main kid who wants to keep it drives a 66 El Camino with a built 454 that runs high 12's in the 1/4 We will ahve to wait until monday to test for vacuum leaks and the O2 sensors.

Later

[97snakedriver]

The usual suspect in this sort of problem is the TPS.

[PKRWUD]

Originally posted by 97snakedriver
The usual suspect in this sort of problem is the TPS.

If that turns out to be the case, tell me all about it! I've never heard of that before. Most potentiometers that have a defect, or become damaged, need to be turned (moved) for the defect to become apparent (kinda like a blind man (you can't "see" electricity") with a wheel; a wheel has to be moved before he discovers it has a flat spot. While just sitting there, it "works" fine).

Hope that makes sense. Anyway, if it turns out to be the TPS, send me the details.

Take care,
-Chris

[BrooklynBrawler]

sup "PK",
i really think that blue 50 should look at the TPS.....y u ask cuz i had a 87 stang and the idle would always surge for no reason , my car was AS PREDICTABLE AS A GIRL..... hahah u never knew when it was goin to act up.......
when i started to look for the vaccum leak there was a small leak
after i fixed it ......the problem persisted......which pissed me off highly !!!!!!!!!
so naturaly i checked the usual suspect which was the TPS and i tried to dial it in..... but that didnt work ......so i disconnected that darn thing and WWWWAALLLLLLAAA!!!!!!!!!!!
problemo finito!!!!!.....
usually if the TPS is in workin order it should behave after its been diald in at bet .7 and .9 on a scale 0 to 1.0 u ll need a gauge to check .......if not u ll need to replace it ...
BLUE"""......ill ask around c if i can dig up somethin on a jap
but ur bet is look at da cars manual .....and look for what we mentioned or, what ever sounds familiar in the jap book.
and if u dont kno or dont have the book ....go to a toyota dealer and ask where the sensors can be located ....a good mechanic in the dealer should be able to help u right away ,......try to avoid the white shits and ties ......they want ur money ......go to the dirtiest lookin person in the shop ......it means he works the most and should have some good info .....
keep me posted i wanna kno what will happen with that......

[PKRWUD]

N.Y.
I understand the thinking, I just haven't seen it, except one time when the screws were a little bit loose, so it was able to vibrate with the engine idling, just enough to cause the TPS to go from a good spot to a bad one. I'm not saying it can't be the TPS, I just like to learn when I can! Keep in mind that I am presuming that no one is touching the throttle at all. When someone feathers the throttle, and it jumps like that, then it is often the TPS, in my experience. Appreciate the input.

Take care,
-Chris

[1969Mach1]

My guess would be the same as PKRWUD check the O2 Sensor, doesn't hurt to check everything while your at it. Does the Supra need alot of work or you guys just building up the engine for racing?

[Dark_5.0]

That a cool project racing is fun no matter what your in as long as its reasonably fast.

Good luck,

[Rev]

Does this Supra have some kind of on board diagnostics? My '94 4Runner does and it will generate a code if I put in a little jumper in the right place (have to read the insstuctions in the manual every time i do it). That would be my first effort. Why not let the computer do the diagnosis if possible.

Rev

[MidNiteBlu 5.0]

Ok well the supra was in a front side wreck which is why it was donated to us. The engine is fine we just had to go to a junkyard and find a new front fender and new bumper. The car will surge like this after you start it up and will do it without any throttle. The interesting part is that if you rev it a little it will die. Monday we will probably work on it again unless someone comes in needing thier freaking axles replaced like we had to do to 3 cars last week

Thanks guys,
Nick

[PKRWUD]

I think you should take Rev's advice. Look for a rectangle "box" with a flip off cover, near the left side strut tower. Connect a paper clip between terminals TE1 and E1 (they're marked). Turn on the ign, and read the codes. A code 1 is normal, anything else is a detected problem.

Take care,
-Chris

[inferno]

Vacuum leak or hole in intercooler piping. Surprised no one sent you in my direction for this one. The first thing you should do with the car is to re-torque the head gasket.....it seems that they weren't torqued down right from the factory and that is why the car has the notorious blown head gasket problem. If you have any other questions about the car, feel free to pm me.

[MidNiteBlu 5.0]

Hey inferno I was hoping for you to respond hehe. Thanks for the help i will have to print this thread out and show it to my auto shot teacher.

Later

[7up]

I used to have three Supras back in the day, 87, 90, and 90 turbo. Sorry I can't help with the problem your having, but a great site to visit for Supra information is

http://www.supras.com/sogi/sogi.php3

Just to let you know the 87 and 90 Supras treated me great and I had very few problems with them. My 90 turbo was another story. I blew the head gasket on it and then blew the engine and I had tons of other problems with it. It seemed like I was always having the thing towed to the shop. I also have had tons of problems with the local Toyota dealership, so have my parents with their Toyotas. It might just be the dealership where I am at, but I thought I would let you know. I have also found that Supras are much more expensive to fix than most cars. A brand new turbo engine from Toyota for thyour year is over $7,000.

Inferno is dead on about the head gasket problem. The supras.com sight even has a section devoted to the 87-92 Supra head gasket problem and a place where you mail your blown head gasket stories to Toyota.

Hope this helps

[inferno]

Umm...a new 7mgte isn't 7 grand. They are not expensive cars to fix or maintain, especially if you are in southern california.

[7up]

That was what my mechanic told me it would be, but now that I think about it that may have been the price installed. So that would make it quite a bit cheaper. My bad.

On another note do you have any idea why the turbos only added 32 horsepower? The turbos were only set at 6psi, I keep reading that turbos are more efficient, but my supercharger added 75 horsepower and it is at 5psi. Is it because of the greater displacement, 5.0 vs 3.0?

[red82gt]

My neighbor has a Toy truck with a Turbocharged 22R motor and it's problem sounds as lot the same, it would idle very badly at 400-700 rpms and then surge to 1600-2000 then back and would lean out if you tried to go anywhere, turned out to be a corroded wire leading to the oxygen sensor, spliced in a new wire and the problem was gone. Oxygen sensors are the cause of a lot of idle problems, I'd look there first.