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View Full Version : leaning out around 4100 - 6000 rpm



7mgt45r
February 2nd, 2008, 10:10 AM
okay, here how goes i had 550cc injectors. Had issues with leaning out at 4100-6000rpm. so replaced them with 780cc and thought that would cure my fuel problem,but it didn't.the car runs great 1st-3rd and when you hit 4th and at 4100rpm it run lean. my setup is 780cc injectors,aem afpr with 6-8inch fuel line kit, 255lb walboro fuel pump. running vpc and safc for fuel managment. turbo is gt45, 4inch all the way bck. motor fully built. i need some help.

AF1JZ
February 2nd, 2008, 10:28 AM
Maybe it's because you are running an SAFC. You might need a standalone to correctly tune the fuel with injectors that big.

DL.
February 2nd, 2008, 12:06 PM
Is it lean when you get into boost? Is your fpr adding fuel via a boost line? Is the vpc chip the correct one? Is the safc removing fuel or adding it?

7mgt45r
February 2nd, 2008, 06:53 PM
Is it lean when you get into boost? Is your fpr adding fuel via a boost line? Is the vpc chip the correct one? Is the safc removing fuel or adding it?

i only have the 550 chip in the vpc. how would you know if the safc is removing fuel when i added fuel?

7mgt45r
February 2nd, 2008, 06:55 PM
Maybe it's because you are running an SAFC. You might need a standalone to correctly tune the fuel with injectors that big.

well i have friends running vpc/safc and with bigger injectors and there's running fine. i ask for help not smart comments can tell your IQ.

Buddafucco
February 2nd, 2008, 07:21 PM
Did you change anything to your set up right before it started running lean?
Wot or part throttle?

Supracentral
February 2nd, 2008, 07:23 PM
i ask for help not smart comments can tell your IQ.

You will be civil on this site or you will be removed from it. Nothing anyone has said to you warrants an insult...

Tone it down or take it down the road.

selfinfliction
February 2nd, 2008, 08:58 PM
i ask for help not smart comments can tell your IQ.



yeah watch out for that IJ. guy too, he's been called a dumby a time or two around here as well


:biglaugh:

turbodriz
February 2nd, 2008, 11:05 PM
There are a few different thngs that can be wrong. What type of fuel pump are u running?

ABQMK2
February 3rd, 2008, 08:28 AM
A friend of mine (supraguy31)had a similar issue. he found that he had a pinched fuel line. R/R the motor so much it got pinched somewhere in the process.

Can you run that big of an injector with a 550 chip in your vpc?

Nick M
February 3rd, 2008, 09:13 AM
Uh, did you see how much fuel pressure you have? I am assuming that is when your turbo hits.

Could be time for a new regulator.

AF1JZ
February 3rd, 2008, 10:36 AM
i ask for help not smart comments can tell your IQ.

You come in here asking for help and that's what I try to provide. I wasn't giving a "smart comment". It's ok though.

ATL88Supra
February 3rd, 2008, 10:46 AM
Sounds like your regulator is going bad, or maybe a clogged fuelline or maybe you wired your stuff wrong.

brake it down and check stuff one by one, i am runnin the same setup but i am using 880 injectors and i have no problems.

besttrans
February 3rd, 2008, 11:26 AM
Simple-
Put a fuel pressure guage on and watch it on the topend. should read base fuel pressure plus 1psi fuel per 1psi boost. example: 35psi base fuel at 30psi boost - fuel guage better read 65psi. If fuel pressure falls off now your chasing fuel delivery- pump, filter*,reg.,lines,etc.
if pressure ok its in the tune..

shawn cassady

dbsupra90
February 3rd, 2008, 12:07 PM
Simple-
Put a fuel pressure guage on and watch it on the topend. should read base fuel pressure plus 1psi fuel per 1psi boost. example: 35psi base fuel at 30psi boost - fuel guage better read 65psi. If fuel pressure falls off now your chasing fuel delivery- pump, filter*,reg.,lines,etc.
if pressure ok its in the tune..

shawn cassady

i agree!

also, how do you know you are running lean? and how lean are you talking?

Doward
February 3rd, 2008, 12:41 PM
I agree with Shawn - look into fuel delivery.

jetjock
February 3rd, 2008, 12:58 PM
^ Me too. If you haven't done the 12 volt mod also look at the FP relay. Check fuel pressure while doing a snap throttle test. Accept no more than a 2-3 psi drop with the regulator hose off and plugged. Check pump current if you can't find a fuel restriction. If it dips look at the pump relay.

gofastgeorge
February 5th, 2008, 06:11 AM
Sounds like you are running out of fuel alright.

Which "Walbro" did you buy?
Many of the low-buck ones being sold by discount people are the counterfiet ones out of china.
Ref: http://www.fuel-pumps.net/walbro-forgeries.html

Or maybe you have the standard 255, not the 255HP.

Or pulling a vacuum on the gas tank ???

supraslo
February 6th, 2008, 11:15 AM
had a similar problem with my setup. Later to be credited to a screwed up tune on my EMS, thanks to some dick who thought he knew how to tune Supras.

Doward
February 6th, 2008, 02:58 PM
He has no EMS - just a VPC/SAFC