I had an oil and plugs change in my 2006 pathfinder and the car started "jerking". The mechanic thought the plugs were probably "fake" so I asked that the old ones be fixed back. This did not stop the jerking. The car would not raise(take fire) either. A computer readout gave a code indicating "multiple random misfire" problem. A lot of causes for this problem were readout including exhaust and air ways blockage. Ultimately the catalytic converter was found to have bursted and scattered in its port. Pieces were evacuated and port welded back by a local panel beater(body shop man). The system was clear, jerking gone and car raised (takes fire) superbly. Two days after, car started smoking and oil was short. Had another oil change. Car continue smoking and goes with oil in a jiffy. Engine sounds fine, compression superb and takes fire fine as expected. But smoking continues with oil disappearing into the bargain.
Are my rings gone? If so what possibly went wrong? If not, please what is my problem and what should I do. I live in Warri, Nigeria and the nearest Nissan place is 6 hours away in Lagos. Cant even try to dive there under this circumstances. Please help!

Cheers!
Ogbon

When you cat broke, abrasive pieces of the ceramic substrate entered your cylinders and damaged the cylinder walls and/or piston rings.
Pieces of the cat may also still be clogging your exhaust.
You have a seriously damaged engine, and my condolences

Hi ezb57e,
Thanks a lot for the info and advice. But how does one know if the cat is going to pack up? Does the cat burst always when it packs up or expires?. Do you have any idea of what Nissan is doing about their cats packing up and destroying their engines?. Honestly, for the experience and the sake of the future, could you tell me what went wrong causing the cat to pack-up after oil and plug change? As you can see I am going through a very expensive experience. So Please help.

Cheers!
Ogbon

Driving with a misfire can damage a cat, and perhaps lead to it breaking up.
Most time you wont know. It might rattle if its coming apart.
I think your oil change was a coincidence.
Cats must get to operating temperature as soon as possible to reduce emissions, so they are made as lightly as possible. Its easier to heat up a small thing than a big thing.
We don't see as many as we did years ago, so maybe they have improved the design by now.
Sorry and good luck.