Peugeot 406 hdi 110,2000 year,power loss,black smoking?

Hello,i have the above motor,the car starts fine,ticks over fine,however it black smokes badly.The car does not want to rev,it will rev but takes about 10 seconds to get it to the red line even when it's stationary.As the rev's rise,the smoke get's worse,when driving(very hard to do) it's hard to see whats behind for the smoke.Diagnostics detected turbo pressure,but the mechanic didn't know where to start looking for the problem.The turbo spins,so he thought it could be a valve or senser faulty.Someone else has sugested the EGR valve might need cleaning,does anyone know the location of this?The engine sounds great,runs so quiet,but is undrivable like this.Thanks for reading,i'd appriciate some help...