[highonoctane16]

Something is incredibly wrong.. to start out, i just did a bhg job on my newly acquired 1990 turbo/targa/auto trans. (biggest job i've ever taken on myself.) putting it all back together, im almost positive i got everything hooked up right...but that could be a possibility, so keep it in mind as you're diagnosing my problem.

anyway, i just finished breaking in the car (300 miles) and changed the oil, so while i was coming home last night at 4 am i figured i'd try to top it out. there was about a 2 mile flat/empty stretch of road on the way home that starts out going downhill before it levels out, so i figured this would be an ideal place to do it. i was cruising along at about 70 so i turned on the ect and turned off O/D. I punched it and it climbed pretty slow to about 90 (at which point to clicked O/D back on.) then, i swear it took about 3/4 of a mile just to get up to 105 at which point it would not go any faster. i did feel it shift into O/D when i turned it back on so that isnt an issue... it was also at full boost the whole time..about 6 psi (stock car.) The car overall runs very nicely...even at 105 it just would not go any faster. i'd have to say that i was sorely disapointed in this since i've gone around 130 in my n/a...

if any body has ANY suggestions, please let me know... No supra owner deserves to have a max speed this slow...

 

[MKIIISupraGuy]

u have an auto from what i gather.

is ur auto tranny healthy?

there was a supra shootout article from back in the day. the test was done by motortrend i believe. anyhow they had a modded auto mk3. it was fast and all but they found out that the tranny fluid was heating up and thinning under constant boost (like when u top it out). so they figure an upgraded tranny cooler was needed. they did get theirs up to like 141mph or so though.

anyhow that's what i think.

and yes 105mph is pretty pathetic. i can do 115mph and that's just in the 1/4 mile

 

[highonoctane16]

thats exactly what im talkin about...it sucks. i was all excited about my new turbo and then the damn thing goes 105.. I dont see how tranny fluid could make a 40mph difference though..

 

[ma71supraturbo]

what are your rpm at?

 

[mdcmotorsports]

I say possible tranny issuses too or something driveline related is binding.
Also, maybe a clogged exhaust?
Is the power poor all the way around and not just on the Hwy?

 

[highonoctane16]

-rpms are right around 3200 if i remember correctly

-i cant really say how the power is cause this is the first supra turbo i've driven. i'd have to say that i wasnt very impressed. its not much better (if not worse) than the performance of my n/a.

 

[AZmkiii]

I say go get it dynoed (50 bucks if you call around, you only need 1 run) you will have a better idea once you get a dyno sheet, see where the power loss is, see if there actually is power loss.

 

[ma71supraturbo]

Something may be up with your TPS because at full throttle the automatic shouldn't shift from drive to overdrive at 105mph. I'm not sure of the exact mph, but Im trapping 105 in the 1/4 (in drive, not od) and its not really that close to the rpm where the automatic would shift into OD. I would estimate 120mph though, so either way you should have been in drive...

Maybe your floormat is bunched up below the gas pedal so you can't push down all the way? Sounds stupid, but a number of people have had it happen to them.


Also, check for codes. And perhaps its time to replace your cats or entire exhaust -- I don't see it keeping you at 105mph verse 145, but maybe its really clogged

 

[highonoctane16]

i happen to have a new tps that the dealership wont take back...so maybe i'll slap that on and see if it will make a difference. the only code im getting is oxygen sensor..which i need to replace, my gas mileage sucks already. i dont see how an o2 sensor would relate to it though...no floormats, i'll check my carpet..

 

[highonoctane16]

new tps didnt make any difference at all.. i also went to friends transmission shop and had it serviced..fluids flushed, changed etc. still cant get over 100-105 though. any suggestions at all?

 

[ma71supraturbo]

compression check? Maybe you have sticking brake caliper? Or like a tire at 10psi?

 

[Guest]

You may want to replace your O2 sensor and see what happens, I had an O2 sensor go out and my car performed horribly. If it thinks that there is too much fuel in the exhaust it may tell the ECM that it's running too rich, or the opposite where it thinks it's running oo lean.

 

[Guest]

Well if you replaced the head gasket and you are gettinmg a O2 code, than you have pluged cats also.

If you put alot of water threw the exhaust when you blew the HG its been sitting there until you started the car again.

Drop the header pipe and the second cat assem. and punch out all the junk in the cats. Put it back together and see what happens. Your cats are junk at this point so your not going to hurt anything. Besides it wont cost you anything to see if this works.

Kurt Sr

 

[Guest]

new tps didnt make any difference at all.. i also went to friends transmission shop and had it serviced..fluids flushed, changed etc. still cant get over 100-105 though. any suggestions at all?

i cant get over 105, but thats because i'm a pussy and afraid of cops