2006 Z71 (5.3 Z vin, flex fuel) with 105,000 miles. Picked up the infamous P0172 and P0175 codes a while back. I've ruled out all of the sensors and anything related to the air intake side through exhaustive testing and have it narrowed down to a fuel delivery problem. I tested the fuel pressure today and have a solid 52 p.s.i. with the key on/engine off. The pressure is dead on 57 p.s.i with the engine running at idle and fluctuates smoothly when accelerated/decelerated. My question is: Knowing that the specs indicate 48-54 p.s.i. at idle, would the 3 extra p.s.i be enough to throw the engine rich codes I'm getting
I'm thinking the answer is no but I'd appreciate your input before moving on to the injectors.
I'll ask for your trust when I say I've ruled out pretty much anything that we normally look at when these codes come up. I've even done the fuel comp. reset and the codes come back. My LTFT's on both banks are pegged at -19.5 but the STFT's appear to be perfect at idle (-3.5 to 3.5 but mostly hovering around zero, they will jump to -5 or -6 briefly when the rpm's are kicked up).
Thanks for your time.
I'm thinking the answer is no but I'd appreciate your input before moving on to the injectors.I'll ask for your trust when I say I've ruled out pretty much anything that we normally look at when these codes come up. I've even done the fuel comp. reset and the codes come back. My LTFT's on both banks are pegged at -19.5 but the STFT's appear to be perfect at idle (-3.5 to 3.5 but mostly hovering around zero, they will jump to -5 or -6 briefly when the rpm's are kicked up).
Thanks for your time.
