Why does my Audi 80's engine make a loud knocking sound when accelerating?

I recently noticed that my Audi 80 makes a loud knocking noise when I accelerate. It seems to be coming from the engine area. What could be the cause of this and how can I fix it?

It sounds like you may have a problem with your spark plugs. Over time, they can wear down and cause knocking noises. It's recommended to replace them every 30,000 miles or so to prevent issues like this.