smoke. . .

I was outside working on my 1992 XJ and i let it idle so that my battery would charge up a little bit, but after about 15-20 min. it started to smoke out the tail pipe. Im running a cherry bomb glasspack and a single cat. (not sure how old it is).

My question is why would it be smoking? Does it mean my cat. is bad?

Thanks in advance
-Garrett

what color smoke? what did it smell like and what was the outside temp. how much smoke? Could be head gasket, condensation in the system heating up and steaming off, could be bad valve seals. Cats don't smoke unless something is getting in there to make it smoke, unless you stuffed a kitty kat in your exhaust.

its white smoke and theres not alot, but enough to where i can see it in the mirrors when it come out from under the jeep, the smeel is pretty mild but i havent seen anything like it before, it was about 50 degrees out at the time

Good possibility your valve stem seals are worn. Not a difficult fix and can be done without removing the head.

if it was sweet smelling it's coolant, head gasket or cracked block/head. Check your oil to see if it's milky, look at the top of the dipstick and under the oil fill cap for milky looking stuff if there is then it's an internal water leak. Then let it warm up all the way, maybe short drive to see if it doesn't go away. If your weather just did what ours did down here it's been cold at night and could still be condensation.