What are early signs of turbo hardware malfunction?

[damnyankee]

I have a 2002 A4 1.8 turbo quattro not that any of that matters but.. I just need to know how do you know when your turbo hardware is going out? Im under factory warranty still and want to get my monies worth and make sure the company isnt telling me that my turbo is fine and it really isnt. Any helpful infromation would be greatly appreciated. I bought the car used and it isnt performing the same as when I purchased it. It lags in power greatly and then it'll have power again. Around what mileage do the turbos start to go out? I know in other model cars the turbo starts going out in about 4-5 years. Well thanks in advance.

[Joshua]

It can be the valve that controlls the turbo that not working correctly.(n75)

Signs of turbomalfuction :
Overboost/underboost
white smoke/blue
strange noise

[El Dingo]

Yes, I agree - white smoke especially if the turbo is on its last legs.
However, your on/off problem sounds like a dump valve problem. Have you had the car on Audis fault reader, or VAG-COM?

[damnyankee]

I would like to say that my car has underturbo? And it does make a loud squealing noise (not the normal turbine spinning noise) I havent heard before. I havent had it hooked up to any computer yet but I will definitely have it done asap. I dont see any smoke yet but I'll keep a look out for any. Thanks for the help and I'll get it chek out now.