2014 Sierra 5.3 L83 Fuel Injectors p2099 misfire

FishinDVM · May 19, 2020

Ok, so 2014 GMC Sierra SLT 5.3L L83. I *HAD* a p050d, and a misfire on cylinder 8 primarily, followed by cylinder 7 also. THIS WAS BACK IN JULY LAST YEAR, 2019, at 87K. I cleaned MAF, throttle body, replaced all plugs and coils, and did a 3 part BG cleaning for carbon deposits... none of which helped that situation. Had to go in to the dealership... I was under 100K miles and under 5 years, by 3 months... they didnt care as injectors are NOT covered under powertrain. They helped me with nothing. Bite the bullet, they said 7 and 8 are bad, I had them replace all eight injectors since we are there.

SO HERE WE ARE TEN MONTHS LATER!!! All was going well, I do mobil 1 full synthetic 0w-20 every 3k, I use ONLY 93 octane, I do a Techron fuel cleaning additive around every oil change, and I never allow the vehicle to go into AFM/V4. Three days ago I get a p2099 (post cat fuel trim rich bank 2). The following day a misfire p0308 on cylinder 8. I hate the chevy dealer, so I take it to a highly recommended engine shop nearby. They did all the small stuff first, not the problem. Then they get down to it, and find the fuel injectors, especially #8 (the worst one last time, NON AFM) look like crap. Stained, corroded, carbonized... He called me just now to tell me they look horrible AND when removing the injector rail, there are no seals underneath on that side. They are about to check out the drivers side and then call me again. Seals are either worn, gone, missing, fell apart, whatever... that also explains the staining under the cover and the burnt oil/gas smell I notice in the cab that I get at startup or when idling.

So.... any ideas as to underlying cause??? Its been under a year and 11k miles since injectors were done. What else can be causing this? IS THERE ANY WARRANTY FROM A CHEVY DEALER ON THE INJECTORS THEY REPLACED 10 MONTHS LATER??? Is it possible the injectors dont seat well within the head itself and this will just keep happening? Is there a better injector to replace it with? Could they have messed up the seals? Any thoughts at all??? I would think if an issue with the head was the case, I wouldnt have made it the first 80K miles without issue in the first place. I just dont want to have this keep happening.

Thank you, Chris