I never heard the whistling sound of the turbo even when I first test drove this car so I don't know if the turbo actually works or not. What are the tell tale signs that the turbo has failed? Do I get a sluggish acceleration? Does the car hesitate when accelerating? I am not sure what it is and I will appreciate if someone could tell me.

 

When you accelerate , it will be gradual. If will produce about 2/3 of its potential power. If you use low octane fuel performance will be slightly worse due to retarded spark.

 

If your turbo has died, you will be in limp mode. You will have 90 hp. And your car will be a slug and you will KNOW that something is wrong believe me. It will not be just a small difference.

You cannot normally hear the turbo spool on a stock A4. Once you are chipped, however, you will hear it quite often.

 

Well said.

 

Speaking of hearing your turbo spool up.... My car has been chipped and yeh i can hear the turbo spool up when i put my foot down,
BUT when i first start my car and im driving for a bit before my engine warms up, if i put my foot down i can hear the turbo spool but its not a really smooth sounding whistle. It sounds more like a fan or something (sounds almost like a fan belt rubbing kind of noise) its not loud but it just sounds a bit odd to me.
This only happens when the engine is cold though.... once its warm its ok....

I havent had any problems at all with the turbo and i have had the car for 8 months now. Any ideas what that noise would be from?

Any help would be great!

 

This may be because the turbo is working hard before the oil has warmed to operating temp.