2020 6.2L: misfires, lifter issues and engine replacement

[B-train]

bad news - i changed the oil + seafoam out for plain oil and it went right back to misfiring after the change.

does this allow me to infer anything, e.g. that it is indeed a stuck lifter and not a broken valve spring?

Did they find anything other than gunk when they pulled the valve covers? A broken spring or bent pushrod should've been easy to see. But, being that you said it drove correctly before the oil change means you're on the right path. Add some more seafoam with your fresh oil and filter change and run it some more. I'd probably put on several hundred miles this go around with some good higher rpm pulls when it's not making any noise.

It's frustrating, belive me (daughter's nightmare lifter). It took some time and finessing, but it's been quiet as a mouse now for many miles. I will say that once a lifter gets gunked up, they are more prone to relapses with dirty oil. You got this man! Show it who's boss.....gently at first of course.

 

[persistent]

i will give the seafoam another shot. i've got an extractor, so i'll just pull a bit of oil via the dip stick tube and add in the seafoam.

do you recommend the same amount (1/2 qt) as before?

i'm leaning towards doing the dod delete mod myself at some point in the near future. nearer if i can't get this lifter unstuck.

according to the dealership, the misfires are on cylinder 8, and iirc that is a normal lifter and not a dod one.

 

[B-train]

i will give the seafoam another shot. i've got an extractor, so i'll just pull a bit of oil via the dip stick tube and add in the seafoam.

do you recommend the same amount (1/2 qt) as before?

i'm leaning towards doing the dod delete mod myself at some point in the near future. nearer if i can't get this lifter unstuck.

according to the dealership, the misfires are on cylinder 8, and iirc that is a normal lifter and not a dod one.

Yep, keep with the same program. It took many miles to gunk it up, so it's gonna take a bit to clean it out. Longer runs of highway speeds are best once you get it to quiet down.

 

[persistent]

another round of 1/2 qt seafoam got the lifter unstuck again, and after 400-500 mi without it sticking again, it's throwing CEL again.

i will try another round of seafoam shortly.

 

[persistent]

as a result of these lifter problems, i decided to do a dod delete myself, which would give me an opportunity to observe and clean the top of the engine.

after taking off the lifter covers, i found no visible sludge. could it be cleaner? sure, but no sludge.

i will cut open my 2 filters from the seafoam runs and post pics of head tops soon.

 

[fr8bil]

K&N.

i was just going off the packaging that said they were good for 20k mi. if the service interval should be every oil change, that's easy enough to adapt to in the future.

i'm really surprised at the amount of crap i'm catching for not changing the filter more often. my recollection of every car i've ever taken to a dealership is that they definitely would not change the filter every time the oil was changed. telling me i'm an idiot for not changing the filter more often does literally nothing to help me make a decision about the repair.

OK, oil filter aside, yes, take the vehicle to an independent but trustworthy, shop ( if you can find one) and have them pull the cam and inspect the lobe that the stuck lifter rides on first. Maybe you can get your problem solved with just a new bump stick if the stuck lifter ground down the lobe, and maybe not, but you also need to run some engine flush a lot stronger than good old Sea Foam through the existing engine and do at least three low-interval oil and filter changes. A decent reman engine with a warranty from someone like Jasper shouldn't set you back $14K parts and labor ( I could be wrong with the damn inflation but it's worth shopping around ) if the cam/lifter replacements fail. Seeing the date of your last reply I'd assume you have addressed the issue by now so overlook the nasty replies you got and fill us in on your progress please.

 

[MrMonte]

Highly recommend installing a non AFM cam & lifters.

I did the AFM delete on my 2018 Yukon Denali 30K miles ago. Took me 20hrs to complete. I didn't pull the engine or drop the oil pan. I did a thread on cam swap.