loss of power not all the time

[sam1966]

just bough a mark gt tdi 150bhp problem does,nt happen all time but sometimes between 2500 and 3000 rev,s it seems as though the turbo cuts out and power of car is,nt there. just had service plus diesel treatment and when problem happens no engine menegement lights displaying on dash. can anyone help

[a8 tech]

check fault memory for sporadic lower boost limit not reached or exceeded (sticky turbo actuator or vaines)If you turn off the engine and restart and the power returns then consider testing the inputs and outputs of the turbo in measured value blocks and test output from 1500 rpm in third gear foot to the floor and compare with actual specification of air quantity and boost pressure.Also consider the airmass but it sounds very sticky turboish.