LBZ: Desired rail pressure all over the place

lmmcbrown0917

lmmcbrown0917

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Oct 13, 2013
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Ok, truck is a 06 100% stock with 65k, customer brought it in saying it smokes sometimes and running rough. i checked codes the only ones were 3 glow plug codes, balance rates are in check.

When i log it with efi live the Desired rail is all over the place all the way from 130-33,000psi driving and idling, however the actual seems ok, idles at 4400 WOT around 25-26k

Anyone had this before?
 
Awenta

Awenta

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Sep 28, 2014
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Desired should max out. Would indicate a bad fpr or bad connection. Run some additive or 2 stroke and it might smooth it out. Or swap it out

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lmmcbrown0917

lmmcbrown0917

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Anyone else ever seen a bad fpr cause this? it idles pretty smooth but has a very slight knock/rattle. Everything else seems to be in check except for the desired pressure.
 
THEFERMANATOR

THEFERMANATOR

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Awenta said:
Desired should max out. Would indicate a bad fpr or bad connection. Run some additive or 2 stroke and it might smooth it out. Or swap it out

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ACTUAL should max out, not desired. Desired is what teh ECM wants it to be, ACTUAL is what it is reading via teh sensor. Unplugging the FCA has no control over desired. Sounds like you have something going wrong with your EFILIVE software if your seeing desired of 33,000 PSI. MAX for a LBZ is 180MPA which is around 26,000 PSI, so you should never see more than that. Sometimes I see weird values displayed on the scan tool, a software update(if applicable) and a restart normally takes care of it. I've also had better luck with later versions doing BBL than pass through scanning.
 
lmmcbrown0917

lmmcbrown0917

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THEFERMANATOR said:
ACTUAL should max out, not desired. Desired is what teh ECM wants it to be, ACTUAL is what it is reading via teh sensor. Unplugging the FCA has no control over desired. Sounds like you have something going wrong with your EFILIVE software if your seeing desired of 33,000 PSI. MAX for a LBZ is 180MPA which is around 26,000 PSI, so you should never see more than that. Sometimes I see weird values displayed on the scan tool, a software update(if applicable) and a restart normally takes care of it. I've also had better luck with later versions doing BBL than pass through scanning.
Click to expand...


i restarted the software a few times and it is up to date, there is definitely something going on with the truck as it is running rough and smoking when you drive it. This makes me think its more than just software acting up.
 
carl.swoyer

carl.swoyer

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Jan 31, 2016
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Fuel pressure regulator is probably sticking

Carl & Christine, 2012 Landmark Rushmore, 2005 Silverado crew cab lt 8 foot bed 6.6 lly /Allison -custom dual exhaust-198000 miles !
 
JoshH

JoshH

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What PIDs are you using to read actual and desired rail pressure? Maybe the PIDs need to be revalidated.
 
lmmcbrown0917

lmmcbrown0917

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JoshH said:
What PIDs are you using to read actual and desired rail pressure? Maybe the PIDs need to be revalidated.
Click to expand...


Using the PIDs on efi live software labeled "Fuel Rail Pressure" and "Desired Fuel Rail Pressure". same ones i always use and i revalidated them a couple times to make sure.
 
x MadMAX DIESEL

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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I would throw a different tune on it. It has to be the tune. Although it is odd because atleast with efi live the max you can set is 200 mpa, which is the highest the stock sensor can read (29,007psi)


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Awenta

Awenta

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x MadMAX DIESEL said:
I would throw a different tune on it. It has to be the tune. Although it is odd because atleast with efi live the max you can set is 200 mpa, which is the highest the stock sensor can read (29,007psi)


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I don't think it's tuned

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JoshH

JoshH

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I think you're getting bad data. Try finding another scanner.
 
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