I posted this on general tech site, but i guess they want specific tech questions on specific model site, anyway, i have a 02 S4 with 39k mi an have had a engine noise mostly on cold start ups after the car has sat idle 2 days or longer. Has been going on since my turbos replacement 6k mi ago. It is a high pitch high rpm noise that sounds like a dentists drill or dry bearing lasting aprox 1min then goes completely away! Any thoughts out there? This noise has appeared on warm startups initially but is getting very infrequent now, like i said above now the noise is after the car sits longer than a day,

 

Well the dentists drill noise you here is the same noise describes by someone witha blown turbo, but cuz it goes away, I have no clue what it copuld possibly be!

 

It sounds like you have a bad bearing in your secondary air pump.

 

thanks for the thoughts. My audi service advisor wants to wait and see what happens. I guess thats ok , still have warranty. Just afraid to go to far from home!

 

For what it's worth...

I have a turbo that whines on cold startups until things warm up. According to my mechanic, it's not an indication of impending turbo failure (and he claims it's been doing the same on his Audi for a while). '00 w/ 66k.