Hey guys, brand new to the forum and new to the website. I have been searching all forums for guidance and things to look into before I registered and started a post. I would like to thank you all in advance. As many others, I am having issues with the P0087 Code on my LBZ and I am at a loss of words.
Truck - 06 LBZ (as mentioned above), 160K, K&N Air Filter, Fass 95 Lift Pump, PPE Downpipe, EFI Live with switch. S&B Tank (62 gal)
Background - I have owned this truck for 7 years. When I purchased the truck it already had EFI Live and an intake system on it. In the last 7 years, I think I have moved to a higher tune on EFI, maybe 5 times to see what it can do. I typically forget about it and leave it on the tow tune 60HP (with the exception of smog). I don't really drive the truck that much due to a company truck. We use the truck to tow our 30ft fifth wheel toy hauler.
Issue - within the last 2-3 months the P0087 code popped up and a P003A Code. I had a good friend who has been a GM Mechanic for 20 + years come over with his scanner and gave me some tips to look a the P0087 Code. He suggested to replace the turbo to remove the P003A Code. The Vanes were sticking and that task has since be complete. Moving back to the P0087 code. I immediately replaced the CAT Fuel Filters. Still got the code. I noticed my lift pump wouldn't hold prime. I contacted S&B Tanks, thinking the Fuel Sending Unit was messed up or clogged, they sent over a new sending unit. Still got the code. Replaced the fuel lines from the tank to the lift pump, still got the code. Replaced the Fuel head assembly in the engine bay and replaced the CAT Fuel filter, still have the code. Replaced the FRPV with a PPE. Still have the code.
I have disconnected the lift pump thinking there was an issue with the lift pump and check the vacuum. All within the correct range.
My buddy and I, finally ran the Tech II as we were driving and the truck starts great, runs fine when cruising around. The issue is when I WOT, build boost and the Rail Pressure Demand is 26K PSI and Actual hits about 23K PSI then falls flat on its face.
Injector Balance rates check out. The FPR Demand and Actual match. When at idle, demanding and actual rail pressure match. We check the fuel lines, they are OEM and in great shape near the Transmission and in the engine bay. FRP at idle (warmed up) Actual and Demand run about 4800 +/-.
The only thing that seems odd to us is the FPR Command % is always set at 41% and when I lay into it, it will drop to about 38-39%. When I let off, back to 41%.
My buddy is kind of at a loss as his has never experienced this at GM. I mentioned to him at others online have stated the CP3 does get tired. He mentioned that he hasn't seen that happen on this year truck as the CP3 were proven and never failed. He doesn't think the injectors are the issue. Oddly enough he has an 07 LBZ with 180K miles and his numbers are relatively close to mine with the exception of the FPR Command %. His starts at 41%, when he revs his engine up, the Command % will drop to 32-34%
Speaking out loud, I feel the FPR is acting up and may need to be replaced.
I just don't know where to go from here as all the minor replacement items have been replaced and now it could potentially turn into big dollar repairs.
I am just looking for some advice on the FPR Command % or symptoms for a "tired CP3". Mind you all, there is no issues with starting it, idle, no white smoke or black smoke no issues with cruising it around. Only when I lay into it.
Thank you
Truck - 06 LBZ (as mentioned above), 160K, K&N Air Filter, Fass 95 Lift Pump, PPE Downpipe, EFI Live with switch. S&B Tank (62 gal)
Background - I have owned this truck for 7 years. When I purchased the truck it already had EFI Live and an intake system on it. In the last 7 years, I think I have moved to a higher tune on EFI, maybe 5 times to see what it can do. I typically forget about it and leave it on the tow tune 60HP (with the exception of smog). I don't really drive the truck that much due to a company truck. We use the truck to tow our 30ft fifth wheel toy hauler.
Issue - within the last 2-3 months the P0087 code popped up and a P003A Code. I had a good friend who has been a GM Mechanic for 20 + years come over with his scanner and gave me some tips to look a the P0087 Code. He suggested to replace the turbo to remove the P003A Code. The Vanes were sticking and that task has since be complete. Moving back to the P0087 code. I immediately replaced the CAT Fuel Filters. Still got the code. I noticed my lift pump wouldn't hold prime. I contacted S&B Tanks, thinking the Fuel Sending Unit was messed up or clogged, they sent over a new sending unit. Still got the code. Replaced the fuel lines from the tank to the lift pump, still got the code. Replaced the Fuel head assembly in the engine bay and replaced the CAT Fuel filter, still have the code. Replaced the FRPV with a PPE. Still have the code.
I have disconnected the lift pump thinking there was an issue with the lift pump and check the vacuum. All within the correct range.
My buddy and I, finally ran the Tech II as we were driving and the truck starts great, runs fine when cruising around. The issue is when I WOT, build boost and the Rail Pressure Demand is 26K PSI and Actual hits about 23K PSI then falls flat on its face.
Injector Balance rates check out. The FPR Demand and Actual match. When at idle, demanding and actual rail pressure match. We check the fuel lines, they are OEM and in great shape near the Transmission and in the engine bay. FRP at idle (warmed up) Actual and Demand run about 4800 +/-.
The only thing that seems odd to us is the FPR Command % is always set at 41% and when I lay into it, it will drop to about 38-39%. When I let off, back to 41%.
My buddy is kind of at a loss as his has never experienced this at GM. I mentioned to him at others online have stated the CP3 does get tired. He mentioned that he hasn't seen that happen on this year truck as the CP3 were proven and never failed. He doesn't think the injectors are the issue. Oddly enough he has an 07 LBZ with 180K miles and his numbers are relatively close to mine with the exception of the FPR Command %. His starts at 41%, when he revs his engine up, the Command % will drop to 32-34%
Speaking out loud, I feel the FPR is acting up and may need to be replaced.
I just don't know where to go from here as all the minor replacement items have been replaced and now it could potentially turn into big dollar repairs.
I am just looking for some advice on the FPR Command % or symptoms for a "tired CP3". Mind you all, there is no issues with starting it, idle, no white smoke or black smoke no issues with cruising it around. Only when I lay into it.
Thank you
