Hi. I have a 2004 uk Audi A4 1.9tdi (130), manual. It has only done 27000 miles but im getting alot of thick black smoke from the exhaust eveytime I accelerate. There is no loss in power and the fuel economy is good. The car drives smooth. I have changed the oil, fuel filter and air filter and have checked the MAF too. Everthing seems fine. What can the problem be? Could it be the catalytic converter?