Help with a misfire - then cat performance

[turbo_bu]

I just had my wife's car lose its crank sensor due to the speed wheel having a bent finger which rubbed through, then took out the sensor. Luckily it happened to me (not her) and I was able to pedal the car (keep having to give it throttle pedal) to get it home (about 2 -3 miles). Long story short, changed the parts and now I get a P0420 low catalytic converter efficiency code. From what I've read, it is suspect that driving with the misfire for those few miles has messed up the catalytic converter. I've reset the code twice. First day, it set on the way to work (forgot to grab the V2). Today, I drove it in and it did not set (log file is attached).

Anyone know if misfire can fry a cat that fast?

Car - 07 Pontiac Grand Prix (3.8L V6 (non-supercharged)) P12 ECM, not supported for tuning, but you can log it :)

[turbo_bu]

Drove it home today. Again, no code. Was looking at the O2 traces. Does it seem odd that the sensor 1 (before cat) appears to be hugging the higher voltage readings? looks like it is skewed toward the rich side. Also, the sensor 2 seems to stay toward the high side (rich) then occassionaly go down (lean). I think that makes sense, but I have never spent much time looking at the 2nd O2 sensor traces.

[ScarabEpic22]

Are you sure its a P12? If it is then its tunable... It might be an E37 too.

Also in that log the O2s are messed up. They should be oscillating, they are pretty static in that log. Just driving for 2-3mi shouldnt kill the cat.

[GMPX]

Erik, I think car uses the PCM that looks like the LS1 PCM, but isn't.

[ScarabEpic22]

Ah I see, scanning with P12/LS1 PIDs probably works fine then.

[turbo_bu]

Are you sure its a P12? If it is then its tunable... It might be an E37 too.

Also in that log the O2s are messed up. They should be oscillating, they are pretty static in that log. Just driving for 2-3mi shouldnt kill the cat.

Yes, its a P12. Looks like one from the outside, and when you try to connect with it, that is the only one that will work.

As for the O2's. Yes, I thought at least the pre-cat O2 (sensor 1) looked odd too. Really not sure about the post cat one (sensor 2).

Anyone ever have misfire mess up the O2's (either pre or post cat ones) such that they needed replaced? I'm guessing that they were kinda fouled by the misfire, but haven't pulled them out to verify. FWIW, drove it yesterday and no code. The real test is the wife driving it today. I guess we will see. I really hope that I don't end up having to replace the O2's and/or the cat.