Supra keeps hitting boost cut

[iamawesome]

My supra is basically stock apart from a front mount and custom intake manifold and hit boost cut occasionally but now iv replaced the stock exhaust with a 3 inch from the turbo an as soon as I use full throttle it spikes to 1 bar and cuts out, is there anyway to stop the boost spikes or is the internal wastegate just not keeping up?

[tsoob]

nice when you get a supra? still got the aw..?

i say boost tap the c**t

[Jonno2002]

1jz i assume ? mine did the same thing, i ported out the factory wastegates and that seemed to fix it, has only hit boost cut about 3-4 times in a year now and thats really cold nights.

[2jayzgte]

Your up Sh*t creek the 3' from the turbo is the problem the 20mm internal wastegate caN'T HANDLE THE EXTRA FLOW hence why it will all way's hit boost cut the only way around it is to either go back to the stock front pipe and then run the 3' from the gearbox back or keep the 3' front pipe and throw a restrictor in it.

With that 3' front puipe if you have a boost gauge you could quite possibly see upto 1.5 bar of boost when both turbo's come online also I had this very probnlem 10 years ago when I first did the samething.

Go check www.mkiv.co.nz you can find most cures for what ales your Supra on that site.

[iamawesome]

Haha nick that was me that came in and got the nuts for the spacers a few weeks ago, sold the aw to buy it

It's a 7m

The 3 inch exhaust is for the 1jz conversion happening in a few weeks but I got failed on a wof for too many holes in my exhaust

[Jonno2002]

ive never heard of 7m's doing that, is the wastegate hose hooked up ? my 1ggte with no exhaust doesnt spike at all, thought it was only the jz's that did that

[iamawesome]

I hope it's hooked up, it never spiked this much before I got the exhaust done

[Looonie]

7M-GTE can hit boost cut anywhere from 7psi to about 14psi. Its based largely upon the temperature of the air at the time as its an air mass related cut (due to the karmann vortex AFM) rather than air flow.

I would presume the front mount is the main candidate, if its aftermarket and higher volume than the stock item, its possible the turbo is filling it up and pulling air through the AFM before the flow is reaching the intake.

You can just use an FCD to artificially raise the boost cut, so long as you are 100% sure your fuelling is fine. Its been a few years so I can't remember the specifics of the unit to use on the 7M, info is probably on Suze's page: http://www.supra.co.nz/fcd.htm

[iamawesome]

It runs filthy rich and Iv got a fcd laying round so I might wire it in

[85AW20v]

Your up Sh*t creek the 3' from the turbo ..........the 3' from the gearbox back or keep the 3' front pipe and throw a restrictor in it.

With that 3' front .......

How the hell did you fit a 3 foot front pipe in there :D

[iamawesome]

Your up Sh*t creek the 3' from the turbo ..........the 3' from the gearbox back or keep the 3' front pipe and throw a restrictor in it.

With that 3' front .......

How the hell did you fit a 3 foot front pipe in there :D

This is why I love toyspeed haha

[cat007]

Yep - boost cut is very easily reached on a 7M.
Get a lexus AFM and some decent 550cc injectors and you'll not meet boost cut again.

As Dave's said - it's the volume of air going into the engine that causes boost cut - colder days/nights will cause it to occur earlier on.

Air filter, exhaust, front mount, all these things add up to bad times with boost cut....

What ever you do though, do NOT get a fuel cut defender.

[iamawesome]

I'm going 1jz so don't really wanna spend money on it, thought there might of been an easy fix, I hear about people putting Lexus afm's on them, what afm is it?

[cat007]

I'm going 1jz so don't really wanna spend money on it, thought there might of been an easy fix, I hear about people putting Lexus afm's on them, what afm is it?

The one off the Lexus V8....Not sure of dimensions...