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Lean spike at shifts

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Old 06-15-2007, 01:59 PM
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Originally Posted by Holty
at this point it wouldn't hurt to try bumping that up a little to see what happens....

TTT for justin

and I bumped it up. Still lean. NO HOLES IN VE JUSTIN!!!
Old 06-15-2007, 03:31 PM
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If a cutoff were to raise it's ugly head, you would see the IPW drop and rise back up quickly, within a frame. Did you post up your tune file, I would like to look at it. I am agreeing, it is fuel/pressure related.
Old 06-15-2007, 08:24 PM
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Originally Posted by 12secSS
If a cutoff were to raise it's ugly head, you would see the IPW drop and rise back up quickly, within a frame. Did you post up your tune file, I would like to look at it. I am agreeing, it is fuel/pressure related.
I figured it out. I just knew it had to be mechanical. I have dakota digital gauges, so they are using resistance to create a reading, no 0-5volt. So I can't put the FP into HPT. Everytime I watch the gauge I have to look at the road again. But when I am watching and glancing it is always saying 64#'s (+-1). Well Today I loaded the VE with ridiculous amounts of values and gave her another shot. IMO the slow creep to lean and then back down is only fuel pressure or inj size. Well we know it isn't injector size. I stared at that fuel pressure gauge and I'll be damned if it didn't go from 64 to 54 in like 2 steps. 64 then 59 then 54. So when ever in the past I glanced over at the gauge i saw the "4" and went back to the road. Son of a bitch.

I went thru a **** load of old scans when I had the 43#'s and did 1/4 mile runs and other WOT runs. I never really caught on for some reason but there was always a "bump" to lean in the 2/3 shift. I just replaced the inline so it has to be a dead stocker or partial stocker or the system just can't handle the pooooooower. And I don't believe the last one. I am gonna pull the stocker and mod a walbro 255 into it. So I'll have 2 255's, one inline and the other in the tank. I guess that should do it.

Josh, emailing a fedex label to you in a few minutes.
Old 06-15-2007, 09:16 PM
  #34  
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got the label, i'll have the pump out to you on monday

edit: i would ship it tomorrow but i have a crazy busy day so i won't have time to drive to the fedex drop off place. sorry....

Last edited by Holty; 06-15-2007 at 09:24 PM.
Old 06-15-2007, 09:23 PM
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Originally Posted by dewmanshu
So I'll have 2 255's, one inline and the other in the tank. I guess that should do it.
as you already know that setup is what fixed my problem completely although i did go one step further and replaced the fpr and added a magnavolt. the most important thing though is that you found the problem.
Old 06-16-2007, 10:47 AM
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Originally Posted by Holty
as you already know that setup is what fixed my problem completely although i did go one step further and replaced the fpr and added a magnavolt. the most important thing though is that you found the problem.
Magnavolt on an 03... Not sure if that's a good thing there josh. Watch your fuel pressure in boost, if it rises more than 1psi per 1psi of boost, then your pressure is increasing too much. Gotta keep that pressure differential constant.

Justin
Old 06-16-2007, 11:31 AM
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Originally Posted by dc_justin
Magnavolt on an 03... Not sure if that's a good thing there josh. Watch your fuel pressure in boost, if it rises more than 1psi per 1psi of boost, then your pressure is increasing too much. Gotta keep that pressure differential constant.

Justin
Does the factory FPR do that? 1 for 1? I didn't think it did. 58pis to 65psi is only 7psi and I have 9.x#'s of boost. (numbers before I realized a lean issue ) So basically is Josh is hitting 67 to 68 psi that should be it! Interesting.
Old 06-16-2007, 01:31 PM
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the magnavolt has absolutely no affect at all on fuel pressure. it was exactly the same before and after i installed it. as far as fuel pressure increase related to boost, it is about .5 psi of fuel pressure per 1 psi of boost on my truck. my MAX fuel pressure is 62psi.
Old 06-22-2007, 06:51 PM
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FIXED!!!



Put the walbro 255 in the tank, 2-3 shift goes to 10:1 if not 9.5:1AFR. It's so rich cause I had the VE inflated to bandaid the issue before.

Holty...my pressure gets to 68psi.
Old 06-22-2007, 08:02 PM
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Originally Posted by dewmanshu
FIXED!!!



Put the walbro 255 in the tank, 2-3 shift goes to 10:1 if not 9.5:1AFR. It's so rich cause I had the VE inflated to bandaid the issue before.

Holty...my pressure gets to 68psi.
cool man cool, i'm happy for you...

but am i remembering correctly that at one point you adjusted your FPR to make your psi a little higher? could that be why you have much higher psi than most?


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