WreckerdSetter

So I did knock sensor on driver side. No change. I found on my buddies scanner that I could activate cylinder deactivation. I did that, and soon as I did the tapping went away. So looks like a bad lifter in cylinder 1. Although still not getting misfire codes which is odd. I've read through companies that make DOD/AFM delete kit to NOT disable AFM through a tuner when you are having valvetrain issues. Going to order new lifter for now and then in a month or so order the full delete kit.

Update: So I replaced all spark plugs with NGK. Truck ran beautiful for couple of minutes, no issues at all when under a load. But after about 5 min truck started to act up again. Hooked up my buddies scanner and test ran, was getting multiple misfires on most cylinders when driving around for 10 min. Just don't understand it. Maybe it is just a knock sensor.

So I've been keeping it in Manual Shifting mode, up to gear 5 and I haven't seen it go to V4 at all. So it's been staying in V8 now, I'll accelerate in 1st to about 3,500 rpm, shifts to 2nd and around 2,000 rpm it just falls on it's face, still in V8.

Just purchased a 2014 GMC Sierra 1500 2.5 months ago with 56k miles, has 63k miles now. 5.3L 4x4. 1.5 weeks ago I heard a ticking, nothing crazy but caught my attention. Got on highway and just had no power whatsoever. Engine light came on (not blinking) as I was heading to store after work. Got back in truck, no engine light, still loss of power. Went to advance, came up as P0324 in historic code. 2 days later had my buddy use his snap on scanner, same thing, ticking noise. When we started it up, had 2 misfires on Cyl#7, and 3-4 misfires on cyl#8. I pulled driver side valve cover, ran it with driver side cylinder ignitions disconnected. No rockers seems different while running. Put all back together and did same on passenger side, no cylinders had ignition on that side, ran it, all seemed ok but ticking went away. But when running just off driver side bank was getting engine light flashing but didn't have my buddy or his scanner. So today I checked knock sensor harness, seemed ok. Went to pull starter to get to knock sensor on passenger side and starter bolt caused an issue so stopped and will deal with another time, was able to reinstall. So I pulled plugs on cyl 4, 6 and 8. Didn't look the greatest. Cleaned them up and swapped them. Drove truck and felt fine for a couple of minutes but started to feel loss of power again but not as bad. As I kept driving it started to get back to real loss of power again. So I bought plugs tonight. Will install tomorrow along with ball joints, which sucks but whatever. I've heard of the AFM lifters, but with cyl#8 having most misfires I'm a bit hesitant to jump to that since #8 isn't an AFM cylinder. Just changed oil about 1k miles ago, synthetic. Original owner was religious about maintenance and is in great shape. Is there something I'm missing? I haven't seen many posts on here for that code. I can do a lifter myself, but obv don't want to. I guess I can give an update tomorrow after new plugs are in, went with NGK. Anyone else have any inputs for what else I should look at tomorrow? Looks like driver side knock sensor harness goes under vacuum pump, behind serpentine belts and connects to main harness by cyl #4. But looked ok. Kind of stuck. Paid $35k for this truck, got rid of my 01 Yukon XL which I loved because I'm expecting a kid and was getting a bit too much. After having to get ball joints and the holidays I'm not trying to blow my savings or have a mechanic do it when I'm able, just having a hard time finding the issue. All help is greatly appreciated.