I've been driving around for a few days now with this unpleasant high pitched metallic grinding noise coming out of the engine. I always put it down to a dying bearing on either the alternator or any of the other things being pulled about by the pulley system.
Shock and horror this morning when I REALLY put my ear to the 1.8 8v TS lump and discovered it'sactually emanating from the throttle body!!! It's imperceptible at low revs but becomes very apparent at over 2000 rpm. It appears to depend solely on engine revs with engine loading making no difference at all. This kind of points suspicion away from it being induction noise of any kind. Is there anything moving in the throttle body? I always thought it's a mess of injectors and oxygen sensors and the rest of it.
had sth similiar - in my case the sound came from a bend vacuum hose, as a side effect it made this whistling sound.
Happened in Italy in the middle of nowhere, first I thought the engine was gone.
I would have never believed that such a small hose could make such a big noise...