Fuel Injectors Running Lean/Rich: P2098, P219B

[RussTheRush]

2016 GMC Sierra 1500 6.2L, 44K miles.

 

It started with throwing codes P0300 and P050D. Took to dealer and they replaced 7 of 8 fuel injectors, one they said was fine.

 

Got truck back and same day threw code P219B, and a couple days later P2098. Fuel mileage has dropped significantly since before injectors replaced (16mpg down to 10mpg 50 mile average). Noted using torque app that long term fuel trim on bank 2 side was averaging 5% leaner, or as much as 10% (LTFT1 18.8%, LTFT2 10.2% at 70mph); cat 2 S1 was 90-100°F cooler than cat 1 S1 (CAT1S1 1490°F, CAT2S1 1396°F); fuel trim shows 5% leaner on bank 2 when truck is accelerating; fuel pressure 56PSI, fuel rail ranges from 1444-1541PSI at highway speeds.

 

Of note: bought truck used at 39K miles and have been running 87 regular gas (didn't know I had a 6.2L till I got the service slip showing that). Cold start and misfires occurred in morning only. What factors could this affect? Also, I have Sprint Booster running in Sport mode.

 

What I've done: checked air filter (K&N with stock airbox), cleaned MAF sensor properly, checked air intake clamps, used propane gas to check for intake air leaks (no rise in throttle).

 

Please advise, other than to return to dealer (coronavirus in San Diego has made things a little tricky). I can send torque app screenshota if need be. Thanks for the advice!

[WhiteLTZ01]

You need to have a competent shop smoke test the intake system for a first step in real diag at this point. There's an unmetered air leak for sure.

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