Hello All

I noticed today that there was a weird rattle when rev'ing the engine up and then letting it drop back down. I would rev the engine to 2500 rpms and then take my foot off the accelerator. When the rpms drop back down to normal the rattling happens around 2K or so while it drops. It idles just fine and when the rpms are running constantly at 2500+ there is no rattle.

Napa guys said a back pressure valve in the exhaust could be causing the issue. The rattle sounds like it is coming from the cat on the passenger side of the vehicle.

Any help would be greatly appreciated.

thanks
ed

 

Cats rattle when bad

 

So the cat is probably bad? Does it matter if I do not replace? I live in Oregon, in a county that does not require smog or emissions testing.