black smoke
 

hi everybody, i am new to this site so i hope someone can help me. i have a passat on a 52 plate,1800 turbo diesel, that black smokes and at peek revs makes a wushing noise.the code reader picked up a faulty air flow meter which as been replaced and the car now flys but still black smokes at peek revs and when slowing down with no revs you can see smoke coming out the back.this then clears when i accelerate.it is not using any oil, the fuel and air filter are new.if i disconnect the air flow meter the car is gutless but there is no smoke wotsoever. could there be a fuelling problem, or is this wushing noise a turbo problem, i have looked at everyinch of the turbo piping and there are no leaks or splits.when we rev it up to max revs the pipes really swell up, should it do this, could the intercooler be blocked and or collapsed on the inside,is there a way of checking pressure to the cooler and out of the cooler.there seems to be lots of pressure going into the manifold but how can i check if this is the correct pressure, also there are lots of pipes going to and from the turbo to all sorts of places and i am sure that if any of these items lead to other units then these need checking. i am almost sure its a air to fuel ratio problem and that the fuel pump and injectors are ok,please help,thankyou for reading, regards vinny