I wish I had access to parts like that but I found out the original owner put the lift and diy fuel filter in. I was looking at the race valve in case my issue was my fprv and its 40and its 40 bucks in shipping to get a damn bolt here. If I knew more about it I would go to the hardware store.

Lowered pw to 28 no differance in butt gauge, no differance in max rail pressure 17500 @ 3200. At this point I am thinking either something in the program is limiting me to 17500 or my cp3 is not capable of producing any more than 17...., or my fprv is letting anything above that go back to the tank, it is shimmed but that doesnt mean its not broke.

try using the scan tool DVT (F12) tools to command max PSI during idle to see if you get the same or different results.

I found out last night I was using the wrong pid to record the fuel rail pressure and my readings may not be accurate (Thanks Josh H) Then I found out I didnt have the correct gm pids listed so I ended up doing a re-install of efi, got the gm pids (all though most of them had a X through them) I went to bed after that.

So in a nut shell I am going to try again tonight weather permitting.

2004lb7 I will try your suggestion tonight as well.

press "shift" & F2 to validate the PIDs. this should remove allot of the X's

Thank you, I came home for lunch and validated them in the truck and got an actual vs desired log. my actual is 17000 psi, my desired is 27000, battery on laptop died before I could do the test you suggested I will have to wait till after work for that one.

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I ran that dvt and nothing appeared to happen until i put a check in the box rail pressure relay i beleive it was and the truck shut off like i turned the key off. other than that nothing that i can tell

get off work yet?

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get off work yet? :chained::work::trapped:

I tried that dvt test and nothing happened. I did click on test relay and truck died like I had turned the key off.

I did bypass my lift pump and that also made no change in pressure. I am going to do a bottle test tomorrow.

I also think I may still have issues with my MAF at idle I am seeing .8 ft\lbs to 1.2 ft\pounds. I have modified the fueling tables to max just to see what is going on and its like I did nothing all the post i have seen say you will see lots of smoke (i dont want to see smoke just an example) and i have no smoke what so ever. So I dont think my changes to my maf setting or fuel limiting tables are doing jack.

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I figured out how to change maf rates, tested in drive way at idle now seeing 5-6 ft/lbs. I did cant leave for a test ride at moment but maybe it will help out.

be very carefull maxing out fueling tables. engine can rev like it's at WOT the moment you start the truck

if you are just maxing out the bottom right corner of the table then you will most likely never hit that point.

the bottle test could tell you allot, if the injectors are returning excessive fuel then the CP3 cant build pressure. this is what happened on my rig.

are you sure this is the reading? MAF should be grams/sec or lbs/min. mine at idle is around 2.8 grams/sec or about 0.38 lbs/min

I should have been a bit more clear by max I ment I copied my normal fuel rate and placed it in the table essentially replacing the 120 max to 170 same as the normal table when running correctly in theory.

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I used the sae.maf pid imperial and it listed it in ft\lbs.

ok, that make sense. have you tried your stock tune and seeing what the rail pressure does?

when you commanded max psi during idle did you log the {actual fuel rail regulator current}? did it match the [B1010 rail pressure valve current] in the tune? 0 or low amps

if the valve current zeroed out per the tune and your PSI is still low then i would believe that ether the CP3 is bad or the injectors are returning too much fuel. the bottle test should tell you if it is the injectors. being that it is an LB7 i would think that it is the injectors.

mine went out last November and i had similar symptoms. it drove around town fine with out smoking much but i didn't have much top end power and couldn't build rail pressure at idle. this eventually got so bad that it started dieing at intersections. then i couldn't even get it to start. thats when i replaced the injectors. runs like a champ now, same CP3.

while i was at it i pulled the CP3 and did the high flow mods to it. had to increase the valve current to pull the idle PSI down when done