Buzzing sound from exhaust.

[02PewterFirebird]

My exhaust is completely stock. Around last week or so whenever I start the car up, the exhaust makes this really annoying buzzing sound for a few minutes. What could this be?

[BLLDOGG]

mine does that when its cold. i think the cat might be going bad

[99W68Firebird]

i think they should have a recall on the stock cats and replace them with some high-flow ones or something.. because the stock one sucks

[2000camarostud]

yeah dude its probably your cat...jeez the GM cats suck real bad or something...everyone's seems to go out.

[KBeezy]

Everybodies cat converters go out sooner or later.

[Linxs]

Originally posted by KBeezy:
Everybodies cat converters go out sooner or later.

Should last longer than 2 years though...

[Timbo1969]

Not necessarily.... Catalytic converters are very tempermental and can go out at anytime without warning.

[777nmp]

Had a problem with buzzing from the electric gas pump on a 98 V6 bird. Nothing you can do, unless, you want to change it

[BadAzzRS]

its your cat making that sound, i have it do, nothing big to worry about, might not pass emmisions, but oh well.

[green97]

Can anyone suggest a high flow CAT that works with the stock exhaust on a 97 3.8 camaro. I almost failed emmisions yesterday and I know my cat is gone cause my exhaust has a buzzing/rattling noise.

[97rs4life]

carsound cat seem to be pretty popular on here and should work with stock exhaust if you get the right size

[green97]

Can anyone tell me what the stock exhaust size is on a 97 3.8 camaro? I would like to order a carsound cat but dont know which one to get.