When I rev up the engine in my Blazer I get a crackle in the exhaust when the RPM's go down. Any idea why? I'll put a video up of it. The quailty is not that great so bear with me here.

 

I know in snowmobiles, when rich fumes load up in the exhaust and they ignite you'll get that (except its more of a backfire), same with EFI kawasaki bikes and straight pipes. I've had it happen to me once on startup... the crank but no start until I tap the gas, then rev it up and you get that crackling.

 

With the engine off and everything cool, bang on your catalytic converter with your fist fairly hard, if you hear a rattle, that's your problem.

Hope this helps,

Regards,

Thomas

 

right. i'm with Tfisher: sounds like something is busted up in the exhaust. shes a 99 and i'm gonna guess you have something like 140-170k miles on 10 year old cats. check the cat, pre cat and muffler, in that order. also, so you know they are expensive to replace in that order (cat = $$$ muffler = $)

good luck and let us know what you find