I was driving home last night from work during rush hour. The highway was like a huge parking lot...took 5 minutes to move a half car length. After about and hour of stop and go the car was starting to miss under load at low rpm (800-1200). I had to hold my rpms up to get the car to go and keep it from dying. The problem then started to progress to even higher rpm and under full throttle the car wouldn't rev higher then 1000 rpm in gear...doh! Then came the smoke and chunks of hot molten catalyst coming out the exhaust. Ah hah!
I got towed back to the shop I work at and cut out the CAT and put in a test pipe. My CAT was totally melted down...hehe! Now I need to find out why my one year old Catco high flow cat melted down on me. Didn't see that one coming! And to think that it breezed past emissions here in Colorado just two months ago.
The car feels much better with just a test pipe in place...I finally have noticable acceleration below 3500 RPM...hehe!

 

Is your engine modified at all or running high compression that might cause you to have hotter exhaust? Or was it just really hot out that day?

 

Well,
I wasn't all that hot...90* or so. As far as I know the engine has been rebuilt once and has compression of 155 PSI across the board. I haven't owned it for all of the 242k miles and have only added 2 1/2" exhaust to it and removed all the excess heavy gadgets. I think I may have had an exhaust leak right behind my CAT in one of my welds as the tube goes over the rear suspension, but as far as I know exhaust leaks behind the CAT on a non oxygen sensor car should have had no effect. Maybe it was just a cruddy CAT!?!?! Its running great now and I kinda like the exhaust note now with no CAT, Dynomax Bullet race muffler, and dual resonator tips. Sounds cool, looks like a beater...hehe!