Originally Posted by #1weatherman
I have a '92 LT1 coupe, and around 45-60 seconds after start up I hear a whining/whirring sounds that lasts maybe 3-5 seconds. the sound resembles that of an electric motor pushing something up or down, and it is not the radio antenna, because it happens whether or not the radio is on, plus the sounds is coming from under the hood. can anyone shed some light on that please? thanks.
Jim aka #1weatherman
Air Injection Reaction (AIR) Pump, part of the secondary system for emissions. The sound is Perfectly normal. It should run at start-up until the car goes into closed loop or ~90-120 seconds. There's a lot of other stuff going on at cold start (ie slightly higher idle speed) that can mask the sound initially. Specifics of operation are in the Factory Service Manual.