i have been asked to help get to the bottom of this the car came in with under boost problems and was traced to faulty oil pump drive causing the turbo to fail. turbo removed and sent for reconditioning,the repairer informed garage too much damage and supplied another unit (no idea as to where it came from) it was fitted back to the car and on road test it lost power and came back after engine cycled on then off until next time under light to medium load.fault codes were 00665 boost pres regulation control range not reached p0299 short with power intermittent.
i was then involved and checked vac system for leeks and correct operation of boost pressure control valve with scope on cont valve supply and ecu signal with vac guage showing good vac supply. ran smoke test on the engine found boost pipe from turbo leaking not fitted properly refitted and retest leek non road tested A1.
vehicle returned to customer
week later its back and now same fault code but after 60 mile drive.garage removed turbo sent back to refurb people they fitted new actuator and sent it back out still the same.
i was asked to take another look so i went back and checked the position sensor at the turbo and feed back to ecu,no vac at actuator 0.4v full vac applied 3.2v.Ad shows 4v at rest and 1v at idle
i have confirmed this with another passat the same and Ad info is incorrect the other vehicle shows .8v at rest and just under 4. with full vac. i have been up there again today and reset the actuator to 1.2v at rest and just under 4v with vac applied trying to get a happy medium as there is no manufacturer info avail for setup of actuator,comes preset from factory with new turbo
now my question is why after 60 miles does it flag fault and does the amm need reseting like the Mercedes?
ps its a 170 passat and it drives really well with loads of power until 60 miles my only other concern is that with oil starvation and a slightly harsh sounding top end could there still be problems caused by lack of oil pressure