Plug in an obd2 with live data. Bring the jeep to operating temp, and observe your timing adv. At 3 different rpms. Also look at your stft and ltft. Unplug the downstream. Take a look at your wideband and recheck your timing at the same 3 points and your fuel trims. Install an aem fic. The tap for the upstream o2 sensor allows you to increase or decrease voltage. Tapping of the downstream isn't required although a o22 tap is provided,... It doesn't effect the tuning of this specific vehicle. Possibly newer vehicles using a factory wideband upstream o2.

OP if you want to replace the downstream go for it I don't see the necessity in replacing non failed parts. If it fails a day after your upstream replacement then fix it.

 

I successfully replaced the upstream O2 sensor today. It came right out with a little heat from the MAP torch and a 22mm flare nut wrench. It runs like a champ now. Thanks for all our help, guys.

 

I successfully replaced the upstream O2 sensor today. It came right out with a little heat on the bung from the MAP torch and a 22mm flare nut wrench. It runs like a champ now. Thanks for all our help, guys.

 

Great! Thanks for the report.

 

Sorry to jump in on this thread but Im having similar issues on my 98 and when I unplug my upstream o2 and let it run it does not throw a code. Is that normal or should I check elsewhere?

 

Not setting a code, or not turning the Check Engine light on?

 

Does your jeep run correctly when you unplug it?

 

For reference, when I unplugged mine I got a code (O2 sesnsor low voltage or something like that) along with a CEL. It ran fine, as well.

 

No code was thrown from unplugging o2 or tps aand let idle for about 5 min. There was no difference in idle when I started the car with o2 unplugged. The car idles worse if the tps is unplugged though. All other sensors will throw codes if I remove them except these 2

 

Open a new thread describe your problem as directly as possible then list what you have done so far. It may be similar to this situation or completely different but should be opened in your own thread.

 

Thank you Cummins93! I was frustrated trying to resolve intermittent dying at idle, intermittent missing/backing off during acceleration, and occasional backfiring through the intake during acceleration. I replaced the IAC and TPS with no joy. Per your recommendation I unplugged the O2 sensor and test drove it. It runs great! Just when I was about to give up on her, after 32 years of faithful service, I'm a happy jeep owner once again! I ordered a new O2 sensor. Thank you for the solution and Happy Trails To You!