New User with a New Supra and New first post !

[XtSupra]

Hello guys, first I would like to let everyone knows that this is an awsome forum.

 

anyway, I finally got myself a Supra (had none-turbo Eclipse and a Turbo GST Eclipse) my new toy is 1995 MKIV TT 6speed with stock turboes but some other mods (down-pipe,Apexi cat back,Greddy FMIC, Cams but not sure which kind since the previous owner never bothered to ask what brand were they, and AEM cam gears)

 

this car sure needs some moinor work, but I am sure it will kick butt. so far the engine runs great but I think I am having a bit of a problem.

 

my problem is, I am getting either boost creep, or my WG is just stuck shut. here is what happens, in first and second gear I get around 1 bar of boost, but at higher gears it will creep to 1.2 or 1.3. this is with no aftermarket boost controller connect, only the stock one. and since I am new to this car, and could not find a decent picture of how the vacum lines need to connect and or the stock boost controller needs to be hooked. so far I found the stock boost controller (the one close to the altenator) has to pipes going out of it, one goes to the bottom niple of the waste gate, and the other one goes to the metal piping on the top of the head and to the intake manifold.

 

and if the stock boost controller and stock WG are working fine, that leaves me only with boost creep because of the down-pipe, catback, and K&N filter? could that be it. there is also a little WG or it just looks like a WG that's almost at the top of the engine closer to the fire wall on the passenger side, is that the second turbo WG? I am sure I read somewhere that these cars run olny one WG, but I could be wrong.

 

and finally, how safe is it to run with 1.2-1.3 boost on stock fuel system along with 98 octane gas? I have EGT on the way, but untill it gets here, is it safe?

 

oh, did I say finally, ok ok one last question, where is the best place to mount the EGT probe (which runner on the exaust manifold), and where is the easiest place to mount it at (downpipe seems easier than exhaust manifold, and if I mounted on the downpipe, what would be a safe temp to run at?

 

 

thanks a lot guys, and sorry for the long post.

 

any help would be greatly appreciated.

[supRo]

Hello and welcome. Most people run the stock turbos upto 1.2 bar max. Someone technical will hopefully come along soon...

 

In the mean time look at the following:

http://www.mkivsupra.net/vbb/showthread.php?t=35926

http://www.mkivsupra.net/vbb/showthread.php?t=35924

 

Ro

[Suprasteve]

welcome !

 

"I found the stock boost controller (the one close to the altenator) has to pipes going out of it, one goes to the bottom niple of the waste gate"

 

stock boost controller ? as far as i know theres no such thing, sounds to me you have a bleed value fitted ? this would explain the boost creep, as i have one and i sometimes get this problem.

 

put a picture up for people to see your car + the "boost controller" you have fitted.

 

If you have a spare £200 buy an electronic boost controller and say bye to your boost creep problem.

[Pete]

You should be hitting fuel cut I'd have thought - does it have a FCD on teh ECU? (Fuel Cut Defender)

If the boost goes up too much the ECU should cut the power as a safety feature. If it goes up to much you AFR (Air Fuel Ratio) is going to be wrong and could be pretty bad. I'd take it easy for a while and get the car checked over to find out exactly what mods you do have. An exhaust restricter might be an idea to reduce the max boost. See Chris Wilson for one of these..

[XtSupra]

I actually do have Greddy Profic B II installed, but the last owner had it unhooked, so I guess I will go ahead and install that. but let me go over the installation with you guys.

 

I will have to unhook the 2 hoses going to the black stock thingy (V somthing or I would guess stock boost controller) and cap these 2 nipples, the hook one side of the controller to the top nipple of the golden WG and cap the bottom nipple on the WG, and hook the other side of the Greddy to the nipple on the Turbo's intake hossing (pressure line), and the rest I am sure I can manage. so simply I control the boost going from the Turbo's pressure side in the turbo's intake housing to the top nipple of the stock WG, and cap the bottom nipple on that WG. right?

 

thanks for your help guys.

[Jake]

Here you go :

[Chris Wilson]

There are some turbo trouble shooting articles and pics somewhere on this forum, that show just how the stock piping should run. Put it back to stock, with no cats you neither need nor want a boost controller, you may need to artificially DROP the boost ( a boost controller can only Raise the boost above wastegate spring pressure, not lower it), by restricting the exhaust to keep below 1.2 bar.

[XtSupra]

Jake, thanks alot for the PIC bro, so I guess I was right afterall. I will try to hook up the boost control and see if that help.

 

Chris, thanks too bro, I do know that boost controler will never drope the boost below the WG spring's rate, I just think that the stock boost controller is not doing it's job as it should, I mean I might have a pressure leak or something that causes it to over boost, and this is why I wanted to try the boost controller that I already have before going into adding cats or putting the stock downpipe back on since I really don't have any stock exhaust parts for this car (bought it with aftermarket downpipe and catback)

 

a question that I already asked eariler is, since most people agree on MAX safe boost with stock turbos, stock fuel system, and stock SMIC on a pump gas (92-93 Octane) is around 1.2bar , well I have FMIC and I run 98 octane gas, does that rule still applies to me, I mean does not running FMIC and higher octane gas allows you to run a bit more boost safely?

 

and finally, where do you guys mount your EGT gauges, which runner is what I am looking for, or should I mount it on the downpipe right after the turbos?

 

 

thanks a lot guys, I really appreciate the help.

[Homer]

Hello and welcome

 

Just to take a step back a little - Is your car a Jap import or an "export" model?

 

If its an 'export' model then I've wasted time typing the following...

 

However, if its a Jap import then the 'symptoms' you describe are normal behaviour for a fully decatted car. The Jap cars have a smaller wastegate than the export models and cannot keep boost down to stock levels. As such, when you decat, all back pressure is released and you will see 1bar in 1st/2nd and 1.2+ in gears above that. Its not boost creep, just normal behaviour on a decatted jap car.

 

In the UK (with our colder air temps, especially this time of year) a car like that would easily see 1.5 bar and be at a much higher risk of a turbo going, in UAE I expect you're still seeing UK summer temps and therefore be around the 1.3 bar region at full boost. Have you checked if your car has a restrictor ring fitted? If imported from Japan then its highly unlikely you will have one. See Chris above to purchase one and keep boost to a decent level (He may need to provide a special one due to the higher air temps you get there though!)

[TLicense]

1.2 bar isn't necessarilly a RON number limit, it's also pretty much an injector duty limit, and also the stock turbo's won't like to constanly be banging out that much. Especially if they're Jap ones.

[Jake]

Especially if they're Jap ones.

Oooo, controversial. Some say the UK turbos are more likely to fail from being over boosted.

[Homer]

After almost 2 years/30k miles of 1.25bar there's still no sign of turbo problems. Bit of smoke on start up but less than when I bought it (stem seals), no smoke on boost. Jap tubbies don't seem any more fragile than UK ones

[XtSupra]

My Supra was purchased from the US, so it's US specs.

here in UAE temps during these days are around 33C-36C during the day and 25C-29C at night. I would love to keep the boost at 1 bar since I do like to keep things closer to the safe side. the funny thing is, I think that the last owner of the car had that problem with the boost, and to solve it, he just unpluged one of the vacume lines in the intake manifold (dumb if you ask me) but I am glad the turbos survived that kind of ubuse (working too hard to pressurize the intake is what I mean), the reason why I knew that is because when I got the car it was not running right, I mean it was slower that it should, but I did not have any boost gauge to know for sure, but after adding a boost gauge, I knew I had a vacume leak somewhere (at idle I was getting close to 0 vacume), and I was right. I fixed the vacure leak and that was when I my boost went from max .6 bar to 1.1-1.3bar at higher gears which is a bit too high for my taste.

 

man, I have been fixing a problem after another eversince I bought this car (5 days ago) I had to fix, Rad, power stearing pump and rack, window's motor, painting the hood, and some other minor stuff, but the moment I got this thing right as it should, all the pain I went through was well worth it.

 

you guys are great.

 

thanks