Chevy Engine Knock: Detonation or Combustion Issues?

I dealt with similar symptoms on my 2019 Chevy Malibu after owning several Chevrolet models. The knock sensor kept triggering, and I experienced the same power loss and engine knock under load. Turned out the combustion chamber had significant carbon deposits causing detonation issues. The mechanic found the deposits were disrupting normal combustion, leading to that rough running and smoke. Complete cleaning of the combustion chambers plus new spark plugs solved it, total repair was 425 including parts and labor. Since your symptoms match mine pretty closely, could be the same issue. But before jumping to conclusions: What's your exact model? What fuel grade are you using? How many miles on the engine? When did symptoms first start? Having moderate experience with engine issues, I'd recommend getting it diagnosed soon. Ignoring detonation can lead to serious engine damage if left unchecked. The knock sensor is trying to protect your engine by pulling timing, which explains the power loss.

Thanks for the input. I've got a 2021 Chevy Move with 137687 KM on it. Been running regular gas since my last service, but you might be onto something with the carbon deposits. The knocking started about two weeks ago, and the engine tuning seems way off since then. My knock sensor is definitely triggering based on the codes. The weird thing is it runs fine when cold but gets worse as it heats up. Started using premium fuel yesterday to see if it helps, but still getting that rough idle and smoke. Just want to avoid major combustion chamber damage before getting it to the shop next week. Would running some fuel system cleaner help in the meantime?

Definitely get your Move checked soon, I totally get wanting to avoid more damage. After fixing my carbon deposit issues, I learned a few key things about preventing knock problems. The switch to premium fuel is smart, but the existing carbon buildup is likely still causing pre-ignition issues. The higher octane will help resist detonation, but won't remove those deposits causing your ignition timing problems. The symptoms getting worse when hot is classic pre-ignition behavior, those carbon deposits get glowing hot and cause early combustion. I ran a quality fuel system cleaner for two tanks before my repair, but honestly, it only helped marginally. The mechanic still needed to do a proper combustion chamber cleaning. The carbon on my cylinder heads was pretty stubborn stuff. One tip: Until you get it serviced, try to avoid heavy acceleration where engine knock is worst. The knock sensor is pulling timing to protect things, which explains your power loss, but there's still risk of damage. The repair cost and process should be similar to what I experienced since we have such similar symptoms. Just make sure they check the spark plugs too, mine were pretty worn from the constant pre-ignition.

Thanks everyone for the detailed responses. Think I'll pick up some fuel system cleaner today, but mainly to help prevent future carbon buildup after getting it properly serviced. The symptoms match the pre-ignition and carbon deposit diagnosis perfectly, especially since it's worse when the engine's hot and the piston slap sound is more noticeable. Will definitely keep babying it until the shop appointment next week. No heavy acceleration, and I'll stick with the premium fuel to minimize any additional cylinder head damage from knock. While the fuel system cleaner might help a bit, sounds like I need that professional combustion chamber cleaning to really solve it. Really appreciate all the advice about the ignition timing and detonation issues. Gives me a much better idea what to expect at the shop. Will update once it's fixed!