i think my catalytic converter is bad. i get a rattling sound from underneath mid car when accerlating through low rpms; slight rattle when rev in nuetral. already checked heat shield. anyone know what bad catalytic converter sounds like?

 

Meow?

 

I had an annoying rattling coming from my catalytic converter area before. I found it was a small bolt that had fallen from the engine bay when I was running a wire into the engine bay from an audio install. I had to remove the heatshield to get at it because it wasn't visible or apparent that it was there, I only found out after I removed the shield and the bolt fell out.
Also, if you have ever lost an oil cap, chances are, it fell behind the engine and could be causing that same rattling sound.

Check all the avenues before plunking down the money to replace the cat.

 

I had a rattle when i put on my invidia exhaust after a few days, but only at idle. i just re-tightened all the bolts and it fixed it for a few weeks until it started again... have a test pipe on it now and no problems at all. if its a metal on metal rattle sound probably just something loose rather than broken cat

 

ya I got the same problem, I should check underneath myself.....

 

 

Just a thought (and in keeping with recent trends) those of you with rattles, have you bothered to check your TCT?

At first, I thought mine was a heat shield rattling somewhere on my POS Mugen but it wasn't.

 

I had the same rattle for 6 months. I thought it was the CAT and those fears were confirmed when I finally threw a CEL. Code came up for the CAT and I replaced it myself. Piece of pie.

-Hockey

 

I also had a bad cat. The core got loose in some way. I thought it was a heat shield, but I got under the car and used one of those stetoscopes(?). No doubt then. I just bought a testpipe. When I took the cat off, I could shake the core more than an inch back and forth... I had a rattle sound sometimes around 2000 and 3000rpm on very specific points. Both when accelerating, and in revving neutral.

Edit: It did NOT say "meow"..

 

yea, checked it out. that's it, bad cat. i'd love to replace it with test pipe or Berk Tech. HFC, but ... i can get cat replaced for free under warranty by my buddy at dealership (even though at 98K miles). looks like another Honda Cat for me.