catalytic converter

I know of nothing I would recommend for this.

If you ran it for a long time with a misfiring cylinder it is likely you cooked the catalytic converter to the point of destruction. Asking for a chemical to repair this is about the same as asking for a chemical to poor over a burned out house that will restore it to new. Not likely.

Does you car fail an actual tailpipe emissions test (the one where they measue things like CO and unburned hydrocarbons) or does it fail becasue the check engine light is on (the sort of test where they just read the OBD2 port)? If it is failing the test becaue of the check engine light, have you actually had the codes checked? It is possible (but not likely) that you cooked the after cat O2 sensor and that is why you are failing the OBD2 catalyst efficiency test. A good shop would know this and be able to diagnose the problem correctly.

Ed

did you check or replace the O? sensors? if not, have you access to a scope? you'll need one to check their reaction time to see if they're healthy. [they may pass self-test, but still be causing problems.]

if you've done the sensors and they're good, but emissions are bad, the cat is cooked - you can't unburn burnt toast.

ccess to a

The O2 is good (Unfortunately?)

sounds like you're talking about the smog test output figures saying O? is good, but that's not what i'm talking about. it's rare for O? to be bad. cat failure is usually NO? - what were your full test figures?

iconlarry wrote in news:beb71d2f-6aa0-4986-aab4- snipped-for-privacy@ct4g2000vbb.googlegroups.com:

No magic potion here, sorry.

Get a "universal fit" cat from any muffler place, probably less than $300. That's about your cheapest fix. Or move to a state that doesn't check the OBD-II during the smog check.