Hi all, I'm in need of some help with my A4 tdi,

ill try to explain the symptoms as best I can so here goes

the following happens both hot and cold, 1st gear moving off from a stand still I very rarely get any turbo, when it does on the few occasions it's very strong and snappy,

throughout the rest of the gears, the turbo pulls very hard after 2000rpm, it seems to be very much faster than the previous one I owned which was exactly the same (possibly this one is remapped)

when the turbo kicks in the black smoke disappears 

many accelaration prior to 2000rpm give a sluggish performance and I big amount of bloke smoke.

i have the engine management light on and when I plugged it in it came up with •mass air flow meter • glow plug circuit fault

i have replaced the mass meter and the problem remains

it does idle slightly lumpy which I have read tons about.

im going to have a professional carbon clean done this weekend to see if this cleans up any sensors that aren't coordinating with each other,

i don't want to throw a loads of money at this replacing parts if I can help it

any help would be great

could this be a dodgy egr, bad injector etc

A good place to start for your smoke issue would be to whip off your egr as it may be coked up. For the engine management light/glow plug circuit warning it mite sound daft but check your rear brake lights.

What year is your A4? Engine code?

Hi rob it's a 2006 2.0tdi sline (140) not sure on the engine code.

rear brake lights seem to work ok including the high level one, 

Have a good luck at the intercooler, it could be split. When was the air filter last changed? Maybe also try a good injector cleaner. 

If all this is preturbo boost I would be tempted to ensure there is no air restriction or leak on the induction side of the engine. Still think the intercooler though.