I've got an '01 A4 2.5Tdi which has been off the road for a while so am currently getting it sorted out to put back on the road.
Before it came off it was having issues with irratic boost and going in to limp mode. So I've used the Innotec Turno Cleaner on the turbo assuming it was coked up, it feels better but it still goes in to limp mode.
So I suspected EGR. Now I've done some searching and it seems like my issues slightly different to others who disconnect and plug the EGR vacuum pipe to make it better, however when I disconnect the vacuum pipe from mine and plug it, it feels the same but if I leave the pipe unplugged and breathing then the car feels much happier and doesn't go in to limp mode.
I blanked the EGR off yesterday and left the pipe connected and it was flat and went limp.
So not sure what the issue could be? Which is the N75 valve? Could it be that maybe? I'd just leave the pipe disconnected for now but that means it'll be sucking in un-registered air won't it?
I appreciate any help!