P0172 Bank 1 Too Rich

[phoon]

Good evening,

I have a 2015 GMC Sierra 5.3L with a misfire problem, note this vehicle does have headers installed and tuned by a "professional".

The problem I'm facing now is that my entire bank 1 is misfiring. So far i have changed all bank 1 injectors, spark plugs + wires and coils.

Any body have any insight or suggestions as to what to try next? I am aware there might be a vacuum leak, maybe?

Also i have opened the valve covers and lifters seem ok. on VCM scanner it appears that my LTFT and STFT on bank 1 are double the value of bank 2 at all times, sometimes more.

Looking forward to any help on this headache-inducing vehicle.

Thanks

[blindsquirrel]

https://forum.hptuners.com/showthrea...og-amp-cfg-too

[phoon]

The vehicle is currently re-flashed. no tune. i could upload my log file later to show you my fuel trim values if needed.

[SiriusC1024]

It has a tune. Read it out and save it. Upload the .hpt.

[phoon]

Ofc it has a tune its currently on a stock tune file. I will show you the headers tune that was on it prior as well, along with the log file. Misfire occurs before and after re-flash, no change.

8-15 Fuel log.hpl8-14 after stock tune.hpt16-07-2023 before o2 delete.hpt

[blindsquirrel]

That's a Gen 5, direct injected.

If you were having actual misfires on B1, the B1 trims would be way positive, not -28%. Misfires do not burn anything in the cylinder, and the oxygen goes down the pipe where an O2 sensor picks it up as 'lean', not rich. O2s are not unburned fuel detectors.

[phoon]

I agree, but the code being shown is saying bank 1 rich.

Cylinder 8 misfire only started when i changed my race wires back to the original ACDelco. Any ideas where i can go from here?

[blindsquirrel]

Any ideas where i can go from here?

The Gen 5 forum, a few doors down from here?

Misfires would show up as lean O2s and positive trims. If you're going to DIY this you need access to the service manuals and diagnostics.

[phoon]

I will take a look. thank you sir