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Discussion Starter #1
just got everything back together on my LB7 brand new FPR.
fired the truck up and its looping /surging at idle when it is in P,R,N,D,3,2,and in 1st gear and it goes away when i accelerate. at idle rpm cage jumps up and down and truck shakes really bad
 

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Welcome to DieselPlace

Please list Year, Make, and Model of your LB7 and list any mods.
Checked for any codes? if so please list them here.
The more info we have the better the diagnostics
(y)
 

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Discussion Starter #3
Welcome to DieselPlace

Please list Year, Make, and Model of your LB7 and list any mods.
Checked for any codes? if so please list them here.
The more info we have the better the diagnostics
(y)
Ok. Its a 2004 Chevy Silverado 2500HD 2WD 6.6 Turbo Diesel. No Mods done everything is stock on the truck.. going to check for codes righrt now.
 

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I had the loopy idle for years before I finally got around to replacing the FPR on my '02. It was recommended that I buy a new Bosch rather than a cheaper aftermarket. Several said that the cheaper ones sold at various online merchants tend to fail quickly. Maybe you got a bad FPR.
My truck runs great, now. (btw: pain in the neck to change the FPR, huh)
 

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Hello
Is it a slight occasional lope or really severe? When I did my head gaskets, while re-assembling the engine, I had in inadvertently disconnected the Fuel rail pressure sensor just below the Bayonet connections the truck would run but idled like a gas engine with a huge cam. I When I reconnected the rail pressure sensor it smoothed right out. I did have the slight occasional surge in idle so I also replaced the FPR while I was in there. My truck would also level out as soon as I gave it enough throttle to get out of an idle situation.
 

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Discussion Starter #7
I had the loopy idle for years before I finally got around to replacing the FPR on my '02. It was recommended that I buy a new Bosch rather than a cheaper aftermarket. Several said that the cheaper ones sold at various online merchants tend to fail quickly. Maybe you got a bad FPR.
My truck runs great, now. (btw: pain in the neck to change the FPR, huh)
hell yes its a pain in the neck to change chevy couldn't make it easy for us.. so i finally got it running smooth again still needs a little bit more fine tuning.. but i think for it having 795,483 miles on the original 2004 LB7 engine it runs great. so after carefully looking at everything my fuel pressure relief valve need to be shimmed or replaced.. did that and after driving it for about 12 hours and relearning the shift pattern it's running great. oh and i did go ahead and replaced my aftermarket (FPR) i went with the Bosch . thank you
 

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Discussion Starter #8
Hello
Is it a slight occasional lope or really severe? When I did my head gaskets, while re-assembling the engine, I had in inadvertently disconnected the Fuel rail pressure sensor just below the Bayonet connections the truck would run but idled like a gas engine with a huge cam. I When I reconnected the rail pressure sensor it smoothed right out. I did have the slight occasional surge in idle so I also replaced the FPR while I was in there. My truck would also level out as soon as I gave it enough throttle to get out of an idle situation.
so i finally got it running smooth again still needs a little bit more fine tuning.. but i think for it having 795,483 miles on the original 2004 LB7 engine it runs great. so after carefully looking at everything my fuel pressure relief valve need to be shimmed or replaced.. did that and after driving it for about 12 hours and relearning the shift pattern it's running great. oh and i went ahead and replaced my aftermarket (FPR) that i just bought and i went with the Bosch FPR. Thank you looks like i got a spare just in case
 

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Glad your issue is resolved.
Thanks for giving us an update!
(y)
 
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