I had been getting 17mpg with my 96 cherokee on 32 bfg m/ts. first bit of abuse i put it through knocked the stock muffler loose and i cut it the rest of the way off. it sounded pretty good and ran fine with just the cat. then driving down the hwy passing a car the thing backfired and blew the cat off and i didnt stop and get it like a dumbA. About the next weekend i had her burried to the doors in a mud puddle and it lost the smooth idle it had had. it idles poorly, kinda like an old souped up racecar... anyway i welded the muffler back on and then noticed i twas going through a gastank quick. checked after a tank and was down to 9 mpg. i dont know what messed up my idle and what it did to my mixture but i know the loss of the O2 sensor in the cat has hurt my mix badly. so my Question.... as been removed, and what could i have messed up in the mud to lose my idle?
Thanks for the help

 

The admins will get on you about that post you may wanna reword it

 

Just fix it the right way.

 

If you hit the exhaust hard enough to tear-up the muffler, chances are you cracked the headers and busted-up the cat, also. That along with the missing, and damaged cat and O2 sensors, could be you main issue. But, mud has a habit of messing up all kinds of things, and getting into places you don't want it. Just spraying it off things in the engine bay can make it worse. Check all vac lines and wiring for damage and mud infiltration.

 

i guess im gonna order a cat and O2 sensor from autopartswarehouse, what do i have to do to reset the computer. is it as simple installing parts and clearing the O2 sensor code. or is it gonna be more than that before i start chasing other problems

 

Knocking that downstream O2 sensor off is what hurt your idle as well as your gas mileage. Your Jeep is meant to run with both O2s. I won't run right without both of them. My sons 87 XJ has the old Renix style with one O2 sensor at the exhaust manifold collector. It has a bad exhaust leak in that same spot and it hasn't ran right since.

 

The downstream O2, the one in the cat, does not affect A/F ratio......the upstream O2, the one beside the motor controls A/F ratio. I think your idle issue may be water in something electrical.