need some expert help

[bmwmteam]

Ok iv got a 99 ls1 trans am, bone stock w/ 57,000 miles. the problem is when i first start the car i get a high pitched hum. if i give the motor just a bit of gas it goes away at about 1,500 rpm, or about 60 on the oil pressure gauge.
but if i do nothing at all and just let it warm up it will hum for 1 to 2 minutes, and just stop instantly. it never comes back untill the next time i start the car. it started only on cold starts but lately it has done it even when the engine is hot. but there has been days when iv gone all day w/ out even a whimper from anything under the hood.

Please please please any help.

[Orcus79]

Could be your AIR pump, they tend to make noise for various reasons. Usually a high pitched whine.

[0rion]

drop that access panel below the drivers side headlight and your air pump will be up in there. Start the car and get down there and listen and see if that's what's making the noise. Sounds like it probably is.

[gnomee]

+1 for the air pump.. You probably just never used it. Whenver the PCM thinks the cats are cold it will turn the air pump on to push air into the exhaust until they heat up.

[Spaz]

Could be your AIR pump, they tend to make noise for various reasons. Usually a high pitched whine.

another +1 for the air pump... mine sounds like a damn turbo whine untill my car goes in to closed loop...

[bmwmteam]

how do i fix it. its very annoying, especially when people keep asking me whats wrong with my car.

[Cutlass]

to fix it you need to replace it. It sounds like the bearings are going bad in the AIR pump. You could start by unpluging it for a few days to confirm that is the source of the noise, but it may set a SES lite that will have to be cleared out.

[2002blackz28]

I also just started having a slight whine and think its the air pump going out. Kind of a bumer thinking other people will here it thinking my car is junk. .............Buy once I hit the throttle I don't care. It only does it mabey once or twice a week