stupid supra problems

[gsxr141]

well, my car suddenly started going up to 14lbs of boost intermittently. i tried turning the boost down, but it didn't help. next i went back to the manual bc i had, and still nothing. i checked for leaks, and i checked the wastegate actuator. no problems found. i finally ran the vacuum line from the turbo back to the wg, and it hit 12psi, but also fc today. the weird thing is, it doesn't hit fc at the same pressure every time. first gear pulls like a train, but second has a hiccup, and the other gears will hit it around 4k rpm on the hiway.
if ANYONE has any insight about this problem, i'm all ears.
thanks..... kevin

 

[hvyman]

Sounds like the wastegate actuator.

 

[gsxr141]

that's what i was leaning towards. i unhooked it to see if the rod moves freely, and it does. i also checked to see if it would stay open if i plug the end of the vacuum line, and it did. i know it's opening because i have a divorced downpipe, but it seems to slowly creep up the longer i'm on the gas. i have 2 extra ones i can try out.
thanks.........

 

[hvyman]

This happened randomly?
Not after installing the ddp?

 

[destrux]

If you have a 7M the fuel cut doesn't correlate with boost pressure, it's based on a certain max airflow value. You can hit that max airflow at different boost pressures in different gears. You're more likely to hit fuel cut in higher gears because they load the engine more and the turbo works better under more load, so you hit higher airflow values more easily.

I don't think you have a problem, other than you're hitting fuel cut. If you're wondering "why now all of a sudden?"... it just got cold out. Turbos and intercoolers also work better in the cold. My eclipse was airflow based fuel cut and till I got an ECU with the cut removed I would hit fuel cut like clockwork every time it got below 50 degrees outside.

Your fixes for this? Well there's the Lexus AFM and a set of 550cc injectors, that will move the fuel cut "up higher" so maybe you won't hit it. Other than that I think you'd have to go standalone, or get a JDM reflashed ECU that has the cut removed.

 

[Turbo Habanero]

Or a FCD but make sure you have a wideband and know what your doing.

Also small boost leaks can cause this.

 

[gsxr141]

i've been hitting fuel cut at what i thought was 8-10 psi on my autometer gauge. i just recently installed a greddy profec b spec 2 and it reads higher that the other gauge. it was still hitting fc around 9psi. i tried installing a fcd that i got from another member, but the car doesn't run right with it installed. it will idle fine, but as you rev it up it stumbles. i have since disconnected it. strangely the car got up to 14psi the last cold morning before hitting fc. you are right about it happening at different times in different gears.
at this point i ran the wastegate back into the turbo like stock. well, it still hit 12psi today, but only hit fc when riding out 3rd or 4th gear. i just want to get it back to stock so i can just drive it.
as far as the other mods, i have a lex afm, walbro 255 and 560's that i'm waiting to install.
thanks for your patience with my weird issues...lol............. kevin

 

[te72]

i just want to get it back to stock so i can just drive it.
thanks for your patience with my weird issues...lol............. kevin

If that is the case, do what I do: remove the boost controller during the colder months. You'd be surprised how easily 14psi comes up on you when it's -15°f...

Also, I would check to make sure your wastegate isn't shimmed. Previous owner of one of the Mk3's up here had the bright idea to use a NUT to shim his wastegate. :nono:

 

[gsxr141]

the boost controller is off. i also removed the washers i had on the wastegate. i drove it last night ans it didn't hit fc. i took off in first and it spun all the way to redline, when i hit second it also spun. it pulled hard as hell, but never hit fc. also, the greddy boost gauge registered 13psi as my max boost hit.