update put the car back together still 2500rpm at standstill took it for an italian tune up.it gave power when needed but no higher than just over 3000rpm still powerful enough but not the 4500 i used to have at standstill.still no codes.no warning lights on dashboard.i will have to look into what steve Q has mentioned the dpf as i have symptons of low power,bit of black smoke from exhaust,diesel fuel odour in the cabin,reduced fuel economy.i thought audi may have picked up on this on thursday the 18th of may as i asked for a health check on the engine. pleased audi realised about the timing though phew..