i need help on the following problem please. my 94 wrx is making a noise when subject to hard acceleration, its very reminisent of a mechanical supercharger whine but isnt turbo or gearbox related. the turbo has been checked and given a full thumbs up days before this noise occured and it still makes the noise when the car is stationary and the engine is reved ..so it doesnt point to the gearbox. when at idle the engine sounds fine but once it gets going ..the sound pops up..then dies off when the revs drop. it winds down over the engine note and ceases at idle. much abliged to anyone that may have a clue to a cure.

 

Try the alternator. I once had a similar problem and had the bearings changed on the alternator. Cost me £100 all in, including removal and refit.