I have a 2004 1500 with the 5.3 that's having issues with sputtering at low idle and when starting to accelerate. It happened when I first bought the truck two months ago so I cleared the codes, cleaned the maf and it didn't come back for a while. The next time it started sputtering I cleaned the throttle body and intake manifold and it quit and the light never came on. This weekend I drove it from Utah to Wyoming and it came on so I got the codes ran and it pulled a P0171 and I believe the other was a P0131. And I was told that was more than likely a fuel pump issue. So I cleared the codes, ran some fuel cleaner through it. And put about 800 miles on it that weekend with no issue. But last night the truck started sputtering worse than ever and the light came back on. The truck only has 120,000 miles on it. Could this be the fuel pump or would it be the bank 1 sensor 1 o2 sensor?

 

It won't be an O2 issue or emissions. My call bad fuel, or filter/pump. You're also in high altitude not sure if one of those codes points to the abs sensor, that "could" cause this issue

 

check the fuel trim with a scan tool...if the fuel trim is adding more than 10% on both banks...you need to check the fuel pressure...if its low...replace the fuel pump and inline filter if it is a system that have a return line to the tank.

 

Thanks for the replies guys! What psi should it be running at?

 

55-62 psi
48-54 psi engine code Z

 

Thanks tech2. I went and ran it through a scanner tool and got
ltbt b1: 25%
Stbt b1: 50.8%
ltbt b2: -3.9%
stbt b2: 6.3%
The mechanic said he would lean towards a vacuum leak or injector before a fuel pump?
the codes this time were
P0300 engine misfire
P0131 low voltage o2 sensor s1 b1
P0171 lean mix bank 1

 

Also I would have checked the fuel pressure but he didn't have his fuel pressure gauge it was loaned out.

 

the new info you posted does not point to fuel pump or vacuum leak. it is isolated to one bank only.

to confirm its a vacuum leak view fuel trim and idle and 2500rpm. obviously, the system must be in closed loop operation. if its lean/adding fuel at idle but normal at 2500rpm...it could be a vacuum leak. if its adding fuel at both idle and 2500rpm...it cannot be a vacuum leak.

1is the misfire constant...a misfire on one bank will read as a lean condition as the02 sees all the unburned oxygen...a scan tool can view individual misfire counters to isolate the misfiring cylinder. if the misfire is present on all the cylinders on one bank...check the 02 sensor.

2create a rich condition...monitor the 02 sensor...if it does not respond...the 02 sensor may be bad.

 

So if it's not a vacuum leak or an o2 sensor what could it be? I will go tomorrow and put a scanner on it again and see what I find

 

I thought the computer compensated for altitude and all that kind of stuff. Cuz I'm in Minnesota and I keep getting bad sensors on both sides upstream and down. Maybe you could help me out too thanks