OK so it started about a week ago, I was driving along the motorway and there was a sudden drop in power, maybe 5-10%. But I accelerated again and the car felt fine, perhaps my foot slipped a bit and I wasn't paying attention properly. Until I was on the slip road pulling away again and in low gears at high revs 2.5/3k revs and more there was a bad noise. Hard to describe but it sounded a bit like a machine gun type noise or something knocking and getting louder the faster something span, if that makes sense.
So into the garage it went, they thought it was the oil pump at first but discounted that. Then VAGCOM was showing a glow plug error upon investigation one of the plugs had the electode(?) come away or something. The car has done about 78k so glow plugs are probably due some time soon. So they were replaced and the car reported working fine.
However driving home when you hammer it in first, second and maybe third 3k revs plus the noise is still there but about two thirds quieter than before it went in.
Performance-wise it feels fine. I'm not 100% sure but I think it's worse the warmer the engine is but that could be a red herring.
Done some googling and searching here and being a noise looks like it could be anything for a heat shield, to an engine mount to many other things.
But anyone any ideas?
The car is a 57 plate A3 170 TDi Quattro