Hi lads i know this is the general plastering section but ive got a plasterers van ? so please help me.. only the past week ive noticed black smoke coming from the exuast.. havent got a trusted mechanic yet .me mate is saying that you should use that diesel cleaning fluid but i have and it doe'snt seem to be working am getting really embrassed now because every time i put my foot down it happens. its a ford transit connect 2003 in your experience is my van fooked.?