Metallic pinging under load, like marbles in a can. Wrong fuel, carbon buildup, or timing.
Low octane fuel in an engine that wants more, carbon deposits, or a knock sensor issue.
Try the octane the manual asks for. If the ping stays, have the knock sensor and carbon checked.
Reading about sounds only goes so far. The tuner on our home page listens in your browser and tells you what it hears. The app goes further: it names the exact fault, checks it against your vehicle, and tells you how urgent it is.