1993 Grand Caravan 3.3L 150K

Hey Guys -

I had a glowing catalytic converter replaced (after several other things, sensors etc) it starts fine and idles ok and runs for about 3 minutes and THIS new universal cat converter is glowing. The cat seems smaller than the one that was on it, is it possible it is too small?

I am trying to find out what various things can make a cat fail. Since owning this vehicle I have replaced cracked head & gasket (was thinking it destroyed the converter, now not sure) cam, crank & map sensors, coil pack, plugs, wires, catalytic converter, all code or "obvious problem" related.

Last code was 43, cam sensor cleared it up. All I have now is a glowing cat, everything else SEEMS fine. NO CODES since I changed cam sensor, may be new codes now? (Already scanned 3X, hoping I am not back to square one).

So...is the cat too small, or is it leaky fuel injector(s) passing unburned fuel, jumped timing chain (idled and ran GREAT til cat glowed) or what? Something is destroying cats on this van or the cat is too small. Also, looks like possible original o2 sensor (1993 only has one) but never got a code for that. Any clues? I know hollowing out the cat is NOT the answer....

Thanks ahead of time! My other post got buried so I am trying again :)

I doubt the cat is too small due to the new designs of the cats. I would check to make sure you aren't putting raw fuel into the cat causing it to overheat. Also check the remainder of the exhaust system to make sure it isn't blocked. As for the O2 sensor, if your mileage is good and not dropping I doubt the sensor is bad. You could have a leaking injector causing it to pour fuel into the cat, also check the plugs as if you have a bad injector it will be carboned up or wet. Good Luck!

Ok now we have some possibilities. I was going to check the plugs for foul out and got sidetracked. So far (2) mechanics have taken their toy obdI scanners and gone home packin. I am ON MY OWN yikes. Ok, sounds like a good place to start. As for the tail end of the exhaust being clogged, I am going to replace the muffler (myself) and see what's the deal. I am assuming it would be ok to run the van sans muffler and tail pipe for a few to see if the cat glows? Will this hurt the cat? I know these things are engineered around a specific window of back-pressure and all of these exhaust components work together in harmony so I would be doing this just for a test, not sure how else to check for exhaust system blockage other than the gauge test which I am not equipped for. At any rate, it acts like a fuel problem, not electric or otherwise, it is misfiring and popping like mad once it gets going but I have no codes. I will hold off on the o2, kind of a drag to change by the looks of it, praying for a clogged muffler. The muffler shop said they checked for blockage and that none of the cat guts (lol) went into the muffler. Wondering how they checked at this point. Thanks for the help, I will repost when I know more. Hmmm...collapsed or clogged muffler maybe? It looks original....

If you have a misfire you may want to change plugs and wires to see what happens. A blocked cat can cause a number of issues including fouled plugs. I would also do a compression check to make sure you don't have a burnt valve. A burnt exhaust valve will cause fuel to leak into the cat and cause your glowing cat problem. Finally, running without a muffler for a short period of time will not damage anything.