Presumably this is a diesel vehicle of some kind. Black smoke is incomplete combustion, which can be caused by partially blocked air filter (change) Or the injectors need servicing, or the injection timing has got out of correct timing,which can be heard by a muffled engine note, as compared with the normal "knock" of a diesel engine.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.