Modded Cp3 dualed with unmodded

JD Dave

JD Dave

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I still can't figure out why my rail pressure goes up and down like a yo yo. I've changed both regulators and it still does it. When I run just the modded pump in the valley all is good. Do you think I should swap out the modded cp3 for a stock one? I just want some opinions. You'd think since it works well on it's own it would work alright with the other.
 
TrentNell

TrentNell

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Jul 7, 2008
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JD Dave said:
I still can't figure out why my rail pressure goes up and down like a yo yo. I've changed both regulators and it still does it. When I run just the modded pump in the valley all is good. Do you think I should swap out the modded cp3 for a stock one? I just want some opinions. You'd think since it works well on it's own it would work alright with the other.
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I am running a stock pump and modded one and have had no problems so far Dave . Have you messed with tunning at all for the modded pump ?
 
SmokeShow

SmokeShow

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Nov 30, 2006
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ditto. I know of others running modded pump(s) in dual cp3 setups without any trouble. One thing diff from you but same as trent is the fact its an lb7... wonder if LMM has an issue there?

Any logs showing the issues?
 
JD Dave

JD Dave

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Rob and Dan are doing all they can to modify the tune and it had improved but not good enough to use. Apparently the LMM are a little different but my truck is the only one giving them problems. I'm not sure if the 120 over injectors help matters.
 
catmenace

catmenace

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Jul 31, 2010
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Mine has been doing the same thing since the PPE CP3 installation. Attempted anywhere from 22,000psi commanded pressure up to 25,500 psi and I get the same result. The actual fuel pressure jumps between 22,000 and 25,000 psi and that is where the surge comes from. It seems that the engine demands the fuel but the fuel being supplied is under uneven pressure under heavy load on the big tunes. Sounds almost like one of those male opera singers warbling under heavy load!!! So far it looks as though there is too much return line fuel. I have the truck in the shop and am having MPI S366/S480 twins installed. We will be installing a restriction on the fuel return line and see if that takes care of it. The Airdog II is not the problem as we checked and it has lots of pressure.
 
JD Dave

JD Dave

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catmenace said:
Mine has been doing the same thing since the PPE CP3 installation. Attempted anywhere from 22,000psi commanded pressure up to 25,500 psi and I get the same result. The actual fuel pressure jumps between 22,000 and 25,000 psi and that is where the surge comes from. It seems that the engine demands the fuel but the fuel being supplied is under uneven pressure under heavy load on the big tunes. Sounds almost like one of those male opera singers warbling under heavy load!!! So far it looks as though there is too much return line fuel. I have the truck in the shop and am having MPI S366/S480 twins installed. We will be installing a restriction on the fuel return line and see if that takes care of it. The Airdog II is not the problem as we checked and it has lots of pressure.
Click to expand...

What happens when you take the second pump off? Are both your pumps stock. From what I've heard LB7's are easy to get rid of it as you have some tables in Efi live that I don't.
 
JD Dave

JD Dave

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05smoker said:
Have you tried a different dual CP3 controller? Ground and power to the controller are both good?
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Ground and power are good. I disconnected the second c3p and left the wiring all hooked up and the one pump ran fine. Also when I unhook the pumps they both go to full pressure. This has been going on for 3 weeks I'm getting a little sick of it. Dan just sent me some new tables to try so I'll keep my fingers crossed.
 
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catmenace

catmenace

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JD Dave said:
What happens when you take the second pump off? Are both your pumps stock. From what I've heard LB7's are easy to get rid of it as you have some tables in Efi live that I don't.
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One pump is the original stock pump and the other is a PPE CP3. We will look at EFI live once everything is back together.
 
JD Dave

JD Dave

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ripmf666 said:
Werd that estelly truck is running fine with the twin pumps and 100 overs and Robs tuning. http://www.duramaxdiesels.com/forum/showthread.php?t=23062

I know they just changed some other stuff around on the OS but I dont want to say since its not my place to. But it was to get more boost off the line with the twins.
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That's why I think I should change the modded pump out. Actually I think I'm just going to do it for peice of mind, I'm getting tired of screwing with the truck.
 
IdahoRob

IdahoRob

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Dave's truck is not the norm.

The Bosch ecm's react very fast compared to the older setups. I've never had this issue with a LB7, but have had a few with LBZ/LMM's but have fixed them with tuning adjustments. I have other customers with LMM's big injectors and dual pumps without this problem.

Controller looks good, tuning looks good, and the regulators look good.
 
JD Dave

JD Dave

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May 19, 2008
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IdahoRob said:
Dave's truck is not the norm.

The Bosch ecm's react very fast compared to the older setups. I've never had this issue with a LB7, but have had a few with LBZ/LMM's but have fixed them with tuning adjustments. I have other customers with LMM's big injectors and dual pumps without this problem.

Controller looks good, tuning looks good, and the regulators look good.
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Changed the modded C3P to a stock one and she runs like a charm now. :D:D:D:D It was alot bigger job then expected but I'm really happy. Only had 5 min to test it because the wife was going out. Special thanks to Rob, Josh and Dan for going out of their way to try and make my truck run right. I'm sure you guys are as happy as I am.
 
SmokeShow

SmokeShow

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Nov 30, 2006
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Where was modded pump from?


Modded pumps seem to have more trouble or trouble more often than oe pumps. For this reason, in a dual cp3 setup, I think it's best to put the modded pump out front as second cp3 rather than n valley. This is So you can swap it out much easier if/when something goes wrong with it. ;)
 
JD Dave

JD Dave

In way over my head
May 19, 2008
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Caledon, Ontario
SmokeShow said:
Where was modded pump from?


Modded pumps seem to have more trouble or trouble more often than oe pumps. For this reason, in a dual cp3 setup, I think it's best to put the modded pump out front as second cp3 rather than n valley. This is So you can swap it out much easier if/when something goes wrong with it. ;)
Click to expand...

Hind sight is 20/20. It was a pump from Floorit diesel, It ran fine by itself but didn't play well with others. It took alot longer then I planned to change the CP3 what a PITA.
 
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