Why does my Audi 80's engine make a strange knocking sound?

I recently purchased a used Audi 80 and have noticed a strange knocking sound coming from the engine. It seems to be more prevalent when the car is idling or at low speeds. I am concerned that this could be a sign of a serious issue and would appreciate any insights or recommendations from fellow Audi owners.

The knocking sound could be an indication of an issue with the engine's connecting rods. This is a common problem in older Audi 80s and should be addressed by a professional mechanic.

I experienced a similar issue with my Audi 80 and it turned out to be a loose spark plug. Have a mechanic check your spark plugs and tighten or replace them if necessary.