I am stumped, I bought an O2 simm from the fastman because I had taken the cat off my truck and it kept turning the CEL on.
I cut the wires to the post catalytic converter 02 sensor and just for kicks I started the truck to see what it sounded like (im always curious...), anyway, I started the truck and it ran just fine, the idle was completely normal, not high or rough. I let it run for a few minutes and it still idled perfect.
I dont think its a big problem but I am just curious if anyone knows why it didnt idle erratically. I thought if you have a bad 02 sensor or if you disconnect one the engine would run terrible. Like I said, its not a big deal but its just going to bother me until I figure it out. Thanks for any help!!

 

Rear O2 doesnt regulate the fuel curves or anything else, it just makes sure the cat is working

 

Actually the rear O2 does affect fuel trim a bit. I wouldn't be surprised if guys with hollow cats picked up acouple mpg with a rear sim.
If you unplug it the PCM will substitute a default value for the missing sensor. It will still run pretty good the downside is eventually the MIL light will come on (usually)
These truck aren't nearly as sensitive to O2 problems as some of the other Chrysler products.

 

Ok thats good to know, i was just curious as to why that happened because I was under the impression it wouldnt run right....
The instructions that came with the simm said to hook it up to the post cat 02 sensor. So I know its on right, and I did pick up a couple MPG, Im now getting double digits!!!