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Discussion Starter · #1 ·
1993 TT supra with HKS carbon TI 3" exhaut/ DOwnpipe/ Apexi flilter/ SSQ bov/ Greddy spec 2 boost controller/ boost and EGT gauge

Ok my car is slow, slow as in a turbo FIREFLY, im back from vacation andi need to fix this problem.

Symptons:

-The car will boost up to 1.2 BAR, but once i hit 1.2 BAR the boost drops DRamatically to 0.5 BAR. car having no power at 1.2 ba

-the car does not pull at all, like i said its 100x slower than the car when it was stock

-The car will hold boost at half throttle, which mean i have to keep my foot pretty steady. ONce i floor it the car loses all its power and boost drops to 0.5 BAR

- Turned GAIN and SET on controller on full and it wont go past 1.2 BAR

-forst turbo spools up fine, second turbo doesnt seem to hold boost or maybe even hit boost??

- no smoke from exhaust, idles fine, no wiered noises etc, car drives fun when not in boost etc

CHECKED

Changed spark plugs...double checked controller wiring/hoses/....checked intercooler hoses......played around with almsot all the settings on the boost controller


to sum it up, on every car pull we do the first turbo wil spool up, and than when th second turbo should kick in the boost drops drmatically to 0.5 BAR. The car has no power

What do you guys think it is, the car is gonna go on the dyno on wednesday, and we are gonna test a bunch of stuff, check turbos etc. But before we do it were looking for your peoples opinions on what it might be, what to check for....and any sites that will teach us more about the supra's turbo systems???????


i
 

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Did you make sure to diagnose all the sequential system components first? Your wastegate vsv is completely out of the picture now with the BC setup you have right? Did it just start happening out of the clear blue sky or was it something that got worse and worse?
 

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Also......is your cruise control working? Check and see if it is working, a bad speed sensor signal (which usually occurs at the odometer connection rather than the sensor itself) will cause screwy boost, if the cruise does not work the VSS signal is not working, if it does work than it is ok (probably not it but one of the easiest things to check) Sometimes this throws a code and other times it doesnt on some people's cars. I would start with the sequential system and the wastegate first though.
 

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Discussion Starter · #4 ·
well i went to a a shop to get the boost controlelr installed.

I went in thre STOCK i came outta there with the greddy BCC/ SSQ/ profec B installed, and it pretty much did all those problem above on my first run.

I havnt gone back their becaause of schedule prblems, but when ic all they THINK the second turbo is dead. BUT how does that happen. The car went it pulling like crazy, and came out slower than stock. I called them on the way home and told them about it but they didnt really say much. Than i went on vacation
 

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Discussion Starter · #5 ·
the cruise control DOES NOT work. I bought hte car and it was working, whiel i was driving the car home i hit a rough patch of road and the cruise control stopped working
 

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Discussion Starter · #6 ·
But the cruise controls topped working on the way home which was in january, the car still pulled hard months and months after

This problem occured 4 weeks ago, right when i let teh shop install the BCC and profec B
 

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From what you just said right now it seems moreso like a botched install on the BC or something else (some BCs install areas are actually wrong) You need to see exactly where they put the BC (also that the BCC is installed correctly) If the BCC isnt installed/tuned correctly you will hit boost cut which will make the car feel like you hit a brick wall. If the BC was not installed correctly/in the right place then you can have many many varying problems (including the one you are having) So first make sure they installed the stuff correctly, then if that checks out OK make sure the sequential system is operating correctly.
 

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MSBTTSUPRA said:
But the cruise controls topped working on the way home which was in january, the car still pulled hard months and months after

This problem occured 4 weeks ago, right when i let teh shop install the BCC and profec B
well maybe the cruise stopped working for another reason, but what I meant was that IF it DOES work, then your VSS signal is most likely fine, but from your last post it sounds like a botched install. Are you local to socali?
 

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Discussion Starter · #9 ·
naw im in B.C.

yA i was thinkin the BCC, but one of the turbo guru's said that boost cut would feel much different.

when its full throttle it feels like the car pretty much stops moving
 

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it stops moving at any boost/rpms? Cause if the BCC isnt installed properly, once you hit over 13 or 14 psi for a certain amount of time it will feel like you hit a brick wall. If you can search and find pics then make sure everything is installed correctly, if not then maybe I can call you/walk you through it and see where they hooked in the BC to make sure it is in the correct location....
 

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Discussion Starter · #11 ·
ahh doesnt matter wat rpms, at part throttle the car will go, my tech said thats because only the first turbo is being used

but at full throttle, doesnt matter if its from a stop a roll etc, it pretty much hit 1.2 BAR than drops, but even when it starts to climb 1.2 its not REMOTELY CLOSE TO BEING FAST.

the boost controller has so many vaccum lines, i would sound dumb tryin to explian were they go LOL
 

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We will talk about this tommorow, I will try and dig up all the pics from here and mkiv.com that I can regarding the sequential system components and wastegate vsv and its configuration so you will have more knowledge about them for when we talk. Then if you are going to be by your car it will be easier to walk you through it and see what exactly is what and if it is on there correctly, cool?
 

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Discussion Starter · #15 ·
sounds good to me............if i could id take pictures, but my USB cable dont work so i have no way of uploading them

that way you coulda seen wat might of been wrong

just outta curiosity...do u think the second turbo is blown?
 

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honda_s2001 said:
Also......is your cruise control working? Check and see if it is working, a bad speed sensor signal (which usually occurs at the odometer connection rather than the sensor itself) will cause screwy boost, if the cruise does not work the VSS signal is not working, if it does work than it is ok (probably not it but one of the easiest things to check) Sometimes this throws a code and other times it doesnt on some people's cars. I would start with the sequential system and the wastegate first though.
Sorry if I jack the thread but my car also have the same problem. It hit at 10 psi but once I stomp on the throttle it goes back to 5 psi. I've check pretty much everything already and nothing I could find wrong. So where is the speed sensor located? Mine is an SC 2jz tt swap. Thanks
 

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its ok, you arent jacking it IMO if we are discussing the same thing.... So you are saying you hit 10psi throughout the powerband and then once you go wide open throttle itll drop? His problem seems to be a bit different, his seems to be that he will boost fine on the #1, but the number2 will boost high and not hold it from what I can gather, tell me a little more about your problem/mods and everything you can possibly add, auto or 6spd?


To MSBTT----If I had to guess, and it would only be a guess with the little info we have swapped at this point, It doesnt seem to be a blown#2. How I assume this, is because A) it was perfectly fine when you dropped it off (so unless they did something to blow the number 2 it should still be ok when you pick it up) But also, even though it is not holding, you still are making 1.2 bar at somepoint, if it was a blown#2 I dont think you would ever see 1.2, in addition to whining and/or smoke, although we can completely rule it out being a turbo problem as of yet. The easiest thing you can do tonight is just take a visual look at all your vac hoses and see if everything is hooked up ok (if you are not familar with any of the parts then all you can really do for now is see if you find popped vac hoses) If something is wrong with the BC or hookup it could be that your wastegate is opening the split second you hit high boost, but we will have to diagnose everything else first, PM me your number right now if you want to do a quick walkthrough (if you are going to be able to be by the car)
 

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James----Forgot to add, that the speed sensor connection that usually causes the signal to be bad is the connection at the odometer that goes bad, is your cruise working? If so, your VSS signal is OK.
 

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Thanks for your help honda_s2001. My car is auto with and up grade TC. it have FMIC, electric fan, 3" dp, exhaust, its pretty much BPU. It main problem is that when I drive and normal throttle of regular it boost fine. But when I step on it, the car shudder and the boost drop. It's very frustraiting diagnose this problem since it's kinda broad I think. I'm pretty well known over at CL and I'm good at lexus V8. This is my first time owning a 2JZ and a turbo car so it all new to me. I swap a 2JZ into my SC400 which use to have a 1uz V8. It was a pretty hard swap too. I hope this info help. If not let me know what more you need. Thanks once again.
 

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I just spent about over an hour with Mickey (msbttsupra) on the phone diagnosing his stuff and believe we made good progress (although he has yet to get around to correcting and checking some of the stuff) but im not so sure it sounds like the same thing you are going through james. Did it just start out of the clear blue sky? Are you positive your tranny is not slipping? If I get around to talking to you on the phone tommorow we can go through a lot of the stuff... I read that you are in socal, around where?
 
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