p1093

[oldwrench]

05 2500HD LLY 170,000 miles

keeps setting P1093 and going into limp in mode. it has no trouble starting, no excessive smoke , and until the code sets runs great.
my understanding is that P1093 is low rail fuel pressure under enrichment, but it seems to set when i lift throttle ,and at low fuel demand. i have replace FPRV (with race plug), fuel rail pressure sensor . and installed lift pump (10psi) does anyone have any ideas witch way i should go with this ?

 

[Brent@LDS]

Factory Injectors/CP3 in the truck?

 

[2004LB7]

test the return fuel on the CP3 and injectors. and don't forget the easy stuff like air in the lines and clogged fuel filters. but with a properly installed lift pump that should be less of an issue

 

[oldwrench]

i have changed the fuel filter even though it was fairly new just to eliminate it as a possibility. CP3 and Injectors are original i did look at freeze frame data a while ago (this has been going on for awhile) the only thing i remember that didn't make sense to me was a desired rail fuel pressure of 140psi and a currant of 120psi

 

[dndj]

i have changed the fuel filter even though it was fairly new just to eliminate it as a possibility. CP3 and Injectors are original i did look at freeze frame data a while ago (this has been going on for awhile) the only thing i remember that didn't make sense to me was a desired rail fuel pressure of 140psi and a currant of 120psi

I believe those numbers would be in MPa, not PSI. 140Mpa = 20,305 PSI.

 

[oldwrench]

ya sorry Mpa. last set of freeze frame data was desired of 120Mpa, actual 103Mpa, @ 2200 rpm. I ran a balance test 675 to 681 accross all 8 cyl. With the scanner on it no matter what i do they are about the same. But when i drive it, it could be half an hour or 5 min but it does it again. i am staring to think it could be an erratic FPR . any thoughts ?

 

[Ron Nielson]

Here is some information that might help you decide a direction to your fix: https://www.duramaxforum.com/threads/2002-lb7-p1093-not-cp3-test.998185/