[SOLVED] 2015 Tahoe L83 P219B and P0306

[hatinthering]

2015 Tahoe, 5.3, 215Kmi. Did the full DOD delete myself at around 200K (BTR cam/lifter kit plus retune), all running like new up until about two weeks ago.
Getting a random (but becoming more frequent) CEL with 219B and 0306. I have swapped coil, plug, wire between cylinders, but misfire stays on Cyl 6.
LTFT at idle is way high on Bank 2 at 20-23%, decreases significantly (below 10%) at cruise/under load.

This is screaming vacuum leak to me, which I have yet to find...next step is to pull intake, maybe bad seal on #6 intake port? Any other Bank 2 or Cyl 6 common vac leak places to check?

If no vac leak, is it reasonable to assume bad #6 injector as the only remaining likely culprit?

I have not yet tried a new O2 sensor for bank 2, mainly because the misfire is consistently showing cyl 6 only.

Thanks for any advice!

 

[Doubeleive]

the fuel injectors are a known issue on the k2's so much that gm made a special 10yr coverage for many.
I would connect a scanner and monitor ALL 8 do it with a cold start and then check again after warmed up.
you might find more than 1 having misfires, they may not throw code as the computer will allow a certain count before it throws a code.
the wifes 2016 had some injectors issue's I wasn't 100% sure but this is how I tested with a scanner anyway to make that determination, after swapping coils/wires/plugs
there was no lifter tick or any other indications that something was wrong, maybe a little lack of power.
it was mostly on a cold start but was also on more than 1 injector. The vehicle was under the 10 year coverage and the dealer replaced all 8 injectors.

 

[hatinthering]

the fuel injectors are a known issue on the k2's so much that gm made a special 10yr coverage for many.
I would connect a scanner and monitor ALL 8 do it with a cold start and then check again after warmed up.
you might find more than 1 having misfires, they may not throw code as the computer will allow a certain count before it throws a code.
the wifes 2016 had some injectors issue's I wasn't 100% sure but this is how I tested with a scanner anyway to make that determination, after swapping coils/wires/plugs
there was no lifter tick or any other indications that something was wrong, maybe a little lack of power.
it was mostly on a cold start but was also on more than 1 injector. The vehicle was under the 10 year coverage and the dealer replaced all 8 injectors.

Thanks for the feedback, I appreciate it. I should have clarified, I have scanned and monitored all 8 cylinders, counts of 0-2 misfires on all cylinders except #6...which gets into the 100s over a drive cycle.
I am leaning toward the #6 iinjector, but dreading the job of pulling those...

 

[Doubeleive]

Thanks for the feedback, I appreciate it. I should have clarified, I have scanned and monitored all 8 cylinders, counts of 0-2 misfires on all cylinders except #6...which gets into the 100s over a drive cycle.
I am leaning toward the #6 iinjector, but dreading the job of pulling those...

ya in that video I had 984 counts on cyl 2, no rotational noise. After swapping coil/wire/plug the injector was the primary suspect. I was monitoring to see if it was electrical mostly or low fuel pressure etc, everything looked normal.

 

[hatinthering]

SOLVED. Just to followup, I did pull the intake and was greeted immediately with obvious blow-by staining from the #6 injector hole. The injector itself may well have been fine, but the teflon seals for the injector in the head most definitely were not. My guess is I had damaged them on install (had replaced all injectors a few months ago while doing non-DOD cam). Injector #6 and all seals on that bank replaced, no codes, good fuel trims, and running like new.