my mondeo made a greating noise a few weeks ago. and gave out a big puff of black smoke as well. now it has no power hardly and get lots of smoke when at about 2500 rpm. didnt have much power before but now is nearly unusable. she starts ok, i have been told it could be the baffles in the exhaust causing it or most likely the turbo, if so can it be repaired or do i need a new one? many thanks. ps the cambelt went last year and i have had the head reconditioned, the pistons and bores looked ok.