disable limp mode?

[0rion]

Still trying to work through a p0087 code on my friend's 06 vin 2. The entire fuel system has been replaced now and it's still setting the code and putting the truck into reduced power. Is there a way to turn limp mode off for that code so I can log and see what the rail pressure is doing if the truck doesn't limp? I want to see if that pressure drops and stays low or if it bounces back. Completely stumped on this truck. New fuel lines, new cp3, new injectors, ect ect and still throwing low rail pressure codes. Very frustrating. I don't want to turn the code off and disable limp as a solution because that's obviously not a good idea but I would like to see what that pressure does if the truck doesn't limp.

[0rion]

decided against doing this.....just not worth the risk of hurting his truck although I would like to know more about the limp parameters and how they tie in with the codes if anyone has the info I'd appreciate it. He's going to take it back to the dealership and see if they can help him troubleshoot it. I just have my doubts that the problem is ever going to get fixed. There's just not many more parts to replace. New cp3 and regulator, fprv tested and passed, new injectors, all new fuel lines, filter head inspected for leaks and the fuel heater checked, new fuel cooler, and new bucket in the tank. I did a log today and saw something very odd with frpdes....it was all over the place. From 30000 down to 1800 in one frame and just kinda bouncing all over the place. Not sure what's going on there and it didn't do that on a previous log from a month or two ago. At this point I'm open to any and all suggestions or advice.

[dansdieselp]

Question. Does it have a lift pump? If so what is your lift pump pressure at the CP3 under load? Is it drawing it through the factory pickup in the tank? Also what pulse are you commanding on what size injectors?

[0rion]

no lift pump, pickup is new stock replacement, and injectors/tune are all stock.

[dansdieselp]

If the fprv is for sure not leaking then I'd say you've got a restriction somewhere. Could be a collapsed line.

[0rion]

I think we're just at the point where someone else is going to have to take over.....all the soft lines have been replaced. It's just been a very frustrating experience. He had it at the dealership once and that's who told us the injectors were bad. The CP3 was done by a different shop. We've done all the rest. I'm just out of ideas and actually have been for a while. I just hope he eventually finds someone that can fix it for him. He's obviously sunk a chunk of change into it so far and it's back breaking that every time we think we have it the code pops within 100 feet of the driveway on the test drive.

[THEFERMANATOR]

Some reading on the P0087 code.

http://www.kennedydiesel.com/docs/Duramax%20LBZ%20and%20LMM%20P0087%20Low%20Fuel%20P ressure%20code.htm