[PsychoRNGD]

...side floor board.

I'm pretty sure its my cat but why would it be heating up the floor enough to melt my carpet
It ruined my carpet and a monster cable! (i don't really care about the carpet )

[CanadianJeep86]

defective heat sheild? too much back pressure in the cat combined with the engine burning too hot?

[EABiker]

Also, if you are running rich, the excess fuel will burn in the cat causing it to overheat.

[Brown Dog]

I've seen this a couple of times. The heat shield is often the culprit, as mentioned by others. I would really suspect the back pressure problem caused by a clogged muffler, or a dead or dying cat.

[JJorda]

I had the same problem, turned out that the exhaust leak I was ignoring was pointing straight up to the floorboard, and directly at one of the drain plug holes. Melted out a drain plug and put a hole in the carpet before I noticed. It only did it on long uphill runs, so I couldn't find anything in my driveway at idle.