o2 simulator

Has anyone had any luck with any O2 sensor sim? Also, will deleting the primary cats make improvements in either performance or mpg that would make it worth doing?

I dont have much tuning experience with jeep computer tuning, I do with gm, so here is my best guess at your questions. O2 sims post cat should work as they just feed a generated signal to the computer that a normal operating O2 would. The post cat 02s are generaly only used to check to see if the catylist is working properly and not used for engine fueling. The pre cat O2s are the ones used for fueling. They check how rich or lean the engine is running and along with other sensor imputs decide how much fuel you need. Unless you are specifically tuned to run with out 02s you could damage you motor by replacing these with sims as the computer would not adjust based on 02 reading even if it needed to. Your fuel economy would probably suffer also.

Most on here are not going to recommend removing emissions equipment.

If you are having issues with the downstream O2 tossing out a "PO420"(engine catylist below threshold) I have read on the internet that you can use Spark plug de-foulers on the O2 to eliminate some of the problem.

Google "Fooling the O2 sensor"