bought this Z28 with the above already on and 32,000 miles. SO, please help with a dumb question :
When I first start up my Z28 it sounds like jet engine winding up cold then after I reverse out of my garage this sound, over top of the normal engine noise, winds down and goes away. Only returns when I slow to a stop now and then and park. What is this?

 

That's your A.I.R. pump.It comes on at all kinds of odd times.It has something to do with emissions.Not really sure exactly what it does,but it doesn't hurt anything.
Kevin

------------------
1998 Black Z28 A4
-------1/8-------
8.584 @ 83.64 MPH
Pics
Camaro/Firebird Birthday Bash

 

Yup, it pumps air into the exhaust to speed up the heating of the cats during start up intensifying the catalytic process. Many people not conserned about emissions get rid the pump and associated tubing.

 

Thanks, I thought it was normal but now I know for sure. This is a very different experience for me, never even owned a V8 b4! So far like everyone else here I love this car.