I've had my Silverado just over 3 years and for any of us that Love our trucks but hate the AFM "snafoo", then you are gonna love this trick.
I too was confused and blind-sided about this Automatic Fuel Management crap, fouling my plugs 1 and 7, drinking a quart of oil withing a week or two of an oil change. When I took my rig to the dealer they were also secretive/deceptive about telling me the truth. Said I had a leaky valve gasket. Actually, they changed the drivers side valve cover, but failed to mention that. It's too bad the engineers or the company that controls the programming won't allow a simple electronic feature to be turned off at the customers request. Especially, when that feature is crap! I believe we can live without AFM, and it doesn't stop me from loving my Chevy.
After a thorough research, checking out alternatives, OBD II adapters(Bully Dog, Flash PAC, Diablo). Those were expensive! It's just one issue causing all the grief. So, I decided I would run my own experiment. There is the ability to shift manually, right? I decided to listen to AFM in Drive and the odd sounds it makes (bla, bla, bla) whenever i let off the accelerator, and the slow down-shifting whenever AFM is on (Drive or M6) when I attempt to come to a stop. But, i noticed it is Not On when I have it in manual D1-D5. So, over the past year (since Jan 2018) I have drove using the Manual 5 (M5) shift settings on my Silverado. Yes, I get in, turn it on, and by habit shift it to M5 (well, if I'm going forward anyways). The AFM is not on! At least I do not have any fouled plugs or that horrible diesel sound the pipes make with it in M6 or in Drive, nor does it eat as much oil. It was a bit nerving at first, because you notice the RPM's are around 2k at 60mph. But, my truck is not something that is economical anyways and I don't drive 75 on the freeways much. There's nothing wrong with only using 5 of the 6 transmission gears. Just wish there was a simple way to keep AFM off and have 6 speeds, but I still get around 11-16 mpg either way. Now, it doesn't shift down as much on some of the hills because it's already in 5th gear. After a while you get used to the fact that AFM is not active, your plugs aren't fouling and you are smiling big because the engine purrs like a dragster or for some, nice and smooth. My plugs are still clean since a year ago and i don't plan on changing them for another year or so. I go almost 4000 miles between oil changes and it still burns about a quart. BTW, i use 20500 or 22500 series long oil filters instead of the tiny crap of a filter (made for a 4-banger) that the specs call for. It has the same threads and diameter, but it's more filter. More filter, better filtering. At 115k the motor is still strong and I'm not easy on it, so I would expect a little blow by oil.
I suggest anyone with this type of vehicle AFM (2007-2013) to try my experiment and see if you come up with the same conclusion. At least I wanted to share my experience and let other owners know what I have found. I'd be interested if anyone else agrees with my findings or what they have to say about it?
2011 Silverado 5.3L LT