Strange Rattling Noise at High RPM

[ledzilla]

When accelerating hard, I've been hearing this raspy rattling at higher RPMs. At least 3500, I think, not completely sure as I always upshift by time I think to look at the tach. I hear nothing while idling or light acceleration. I don't think it's the trans as I was hearing it before I swapped the trans out last summer. Anyone have any thoughts on this?

[crownvic97]

When accelerating hard, I've been hearing this raspy rattling at higher RPMs. At least 3500, I think, not completely sure as I always upshift by time I think to look at the tach. I hear nothing while idling or light acceleration. I don't think it's the trans as I was hearing it before I swapped the trans out last summer. Anyone have any thoughts on this?

Could be pinging?

[Fastbob]

Catalytic converter? Take a rubber mallet and hammer on the catalysts to see if they rattle. Do this when they are cool or you will melt the rubber mallet.

[ledzilla]

Catalytic converter? Take a rubber mallet and hammer on the catalysts to see if they rattle. Do this when they are cool or you will melt the rubber mallet.
This seems like it could be it. Guess I'll need to buy a rubber mallet. It really sounds like something loose ratttling around really fast, as it sounds kind of tinny.