catalytic converter trouble

[patricksharon]

I have a 01 kia sportage, 4 wheel drive, automatic. The bottom catalytic converter was clogged so I had it replaced. I changed the upper and lower Oxygen sensors. When I took the heat shield off the exhaust manifold, I saw that the exhaust manifold was cracked, so I replaced it. When I removed the old manifold, I checked the upper catalytic converter and saw that it was bad, too (the ceramic was actually melted). So, obviously, I replaced it.

So now that I've replaced this stuff (2 converters, 2 O2 sensors, and the exhaust manifold), is there anything else I should replace or do to prevent this from happening again? I was told that the reason these parts failed in the first place was because the engine wasn't running right. Is it possible that when the bottom converter clogged up, it caused the extra heat to damage the parts above it? If so, what caused the bottom converter to clog up to begin with?

Any ideas on this situation would sure be helpful! Thanks, Pat

[kiaracer]

kia recalled the warm-up cat on a lot of the 1st gen sportages because they failed due to a manufacturing defect. if it wasn't replaced under the recall yet, this is the reason the pre-cat failed and clogged the 2nd cat. most of the time the pre-cat will fail and the ceramic catalyst will break up and fall down the downpipe and get clogged in the main cat. if it's already been replaced under the recall and you've had to replace it again chances are the engine can be running rich causing raw fuel to make it into the pre-cat and burn up which will cause the cat to overheat and break up. if it's running rich, you're gonna have to figure out why or you'll be replacing the cats again.