2014 l83 Sierra

[Bettywhite]

So first thing I changed spark plugs and then everything went wrong started misfiring on 4 and 6. That's the beginning 3 months nothing but problem after problem. Cat went bad replace the whole y pipe. Then lifter went on 6 pulled everything all new lifters and pushrods 4 new fuel injectors. Fixed okay now lifter went bad on 4 pulled everything replaced all lifter and push rods again got everything back together and now misfiring on 6. Afm is disabled but not deleted. What to do its been 2 or 3 times now within 3 months 

 

[Jsdirt]

If it were mine, I'd be buying a new crate engine from a builder (NOT GM) without AFM (if that's possible on these newer ones), then have it dyno tuned. Either junk parts, or something got screwed up in the block, sounds like.

 

But before going scorched earth on that, check and make sure it's not something as simple as a cracked spark plug, carbon tracking, or a bad coil, or a failed injector or wiring. A compression and leakdown check would be in order, too - that will tell you for sure if there's another valvetrain problem going on here. 

Edited May 7, 2022 by Jsdirt