Fuel cut ?'s for 550s with Lex

blk91

Member
Aug 29, 2005
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ca
Hi I was looking at a freinds supra with a Lexus and 550 set up with a 60-1 bolt on turbo and the car is hitt fuel cut between 14-15 psi . I was thinking that was a bit low but I have never run that set up, Also the car is running a stock IC and piping and it seems to me that the setup would have a lot of pressure drop at that volume of air. Does The fuel cut sound like its in the right place to everyone else, And could the Intercooler effect that?
 

Poodles

I play with fire
Jul 22, 2006
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Fort Worth, TX
Fuel cut is based on the amount of air past the AFM. Doesn't matter on PSI...

Larger turbo will flow more air at a lower PSI.

Stock intercooler is one of the best intercooler put on a stock car (though I think some of the ones on modern cars trump it), so it's not that big of a restriction. The piping isn't bad, but it tends to leak and as most of the pipes are soft, they will balloon a bit.
 

Bigdough666

Picture Me Rollin
Apr 4, 2005
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Corpus Christi, TX
^^^What he said.

Thats about the right level. You wont be able to run any higher boost until you start tuning the car with some sort of fuel computer and adjusting fuel pressure with a regulator. Add a Walbro, S-AFC (or something similar) and a AFPR and you can crank up the boost.
 

ihiryu

Member
Jul 12, 2008
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/\/\/\ can you elaborate on that? I'm the same boat as blk91's buddy. I've already got the screw all the way out, and the AFPR is at 60, but it seems like I can only run 10 psi before I hit FC
 

jdub

Official SM Expert: Motor Oil, Lubricants & Fil
SM Expert
Feb 10, 2006
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ihiryu;1168149 said:
and the AFPR is at 60, but it seems like I can only run 10 psi before I hit FC


That FP is way too high :aigo:
I have mine set at 27 psi (vac on).

Like Grim said, check for boost leaks.
 

CajunKenny

PULL MY FINGER. PLEASE!
Nov 15, 2007
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Washington
Why in the world do you have your fuel pressure set at 60!?!?!?

It's already been said. The car needs to be tuned! You don't have the necessary mods to SAFELY run more boost. Sure there's a little play room; but, only a LITTLE!

Save up some money and get the rest of the recipe for more power. :icon_bigg
 

ihiryu

Member
Jul 12, 2008
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TX
I'm pretty sure I don't have boost leaks, I did all my IC piping in metal and it's all welded up with exception of three couplers. I think I do have the supporting mods, LEX AFM, RC550's, SAFC, 2mm hg, afpr and arp headstuds. And I have a 2jzget. I don't think it's really at 60, I think the gauge is fubar'ed. My new one should be coming in soon.

The reason why it's at sixty is cause it doesn't like to idle anywhere else. I'll put it down to 45 and the idle will drop to a low 650-700 when the car is first started.
 

CajunKenny

PULL MY FINGER. PLEASE!
Nov 15, 2007
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Ah... Now he posts his mods list! ;D

Yeah, get that gauge replaced so you'll know where your fp is at.

As stated above I'd check for boost leaks. You could have a pin hole or two in the IC or pipe. There's a DIY sticky somewhere that shows how to build a boost leak tester for like 8 bucks with parts available at any Home Depot.
 
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Rennat

5psi...? haha
Dec 6, 2005
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whats wrong with a 650-700RPM idle? my car idles at that, and it makes it nice and quiet when im just sitting at a stop light...

do you have a wideband? cause i see you have all the other stuff..
 

grimreaper

New Member
Jul 2, 2008
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the fact that you stated your going off of busted (or unreliable) gauges would signify postponing most head scratching until you have reliable data.
 

MKIIINA

Destroyer of Turbos
Mar 30, 2005
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Plano, TX
there's a few holes here that I think need to be filled in to get a real answer. You say you have a 2jz and yet in this thread -> http://www.supramania.com/forums/showthread.php?t=82828

you say you have a 7M. fp set at 60? you had some breaking up at 3k-5k rpms, has that been resolved? Where in ca are you located as having someone who is a bit more familiar with the MK3 might be able to help with some hands on diagnostics....
 

ihiryu

Member
Jul 12, 2008
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TX
yeah I have a 2j running 7m stuff. but again nothing for sure until the new gauge makes it
 

ihiryu

Member
Jul 12, 2008
209
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TX
refer to post 15.

I also think I'm going to do the 12 volt mod. I never really thought about it until I saw a thread bumped up today.
 

ihiryu

Member
Jul 12, 2008
209
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16
TX
just for the sake of tuning. I mean why not right? I've done it on my other cars, just haven't done it to this one. I've only had the car for a few months, and I'm really trying to work all the kinks out of her. I love the car, it's just upsetting me with all these lil problems i'm having /end rant.

Sorry i had to say that