Hello, Ive just bought an 09 reg Focus 1.6 style. When I start it on a morning I hear a single clunk (or click) sound usually after about 100 yards. It seems to come from under the front right hand side of the car possibly near the accelerator or the engine near the accelerator. Someone said it might be the air control unit clicking in. Does anyone know if that is usual or could there be some other problem? Thank you