I just want to update and confirm these lifter issues are a real problem. At 25000 miles I had the check engine light intermittently turn on with engine misfire and rough shifting. Had the dealer look at it three times, first time they reported cylinder miss #4, reset codes. Second time back same problems and codes, they replace the spark plug. Third time same problems they replaced the lifter, solenoid and wire harness for DFM. Truck ran good until now 67000 miles, same problems, 1st visit dealer changed spark plug, 2nd visit dealer changed intake manifold, 3rd visit, they still have it changing lifters, piston and ring in #3 cylinder. That seems like a major amount of work, I do not know if the engine has to be removed to take the oil pan out to get the piston out?
Dealer has been great suppling loaner car each time and covering under warranty. I always changed the oil at recommended intervals with proper oil. I am really worried about longevity of this motor. I see that Michigan motors has a DFM delete kit that has standard lifters and plugs for the DFM solenoids.
Here is the link: https://www.michiganmotorsports.com/camshafts-michigan-motorsports/dod-afm-delete-kits/2019-l84-5-3-dfm-lifter-delete-kit-dod-afm-5-3l-gen-v-kit/
I asked the dealer about this and they said one of their employees installed this and blew the motor. This is even more alarming. Has anybody had similar experiences and has anybody installed the DFM delete kit?
I had a 2004 2500 Duramax (LLY) that I traded in for this truck, it had 275000 miles and I had to replace one injector. Wish I never got rid of it.