Why does the Audi A6 3.0T engine make a rattling noise?

I recently purchased a used Audi A6 with a 3.0T engine and have noticed a strange rattling noise when accelerating. It seems to be more prominent when the engine is cold. Does anyone know why this might be happening?

The rattling noise could potentially be coming from the direct injection system in the 3.0T engine. It's a common issue with this engine and can be fixed by having the injectors cleaned or replaced.