Dave51

I don't believe the workarounds would have any bearing on that as they only relate to power.

Do you have any engine codes?
Do you have an OBD tester? If you're going to start doing your own work a reasonably good tester will be able to confirm a lot of issues.

In answer to your question, there's a chance, even a good chance that's it's the upstream oxygen sensor, but let's see if we can get some confirmation on that.

Matt_the_Butcher

I've done that trick a few times before, even with the ignition bypass & no codes. I have an obd2 Bluetooth connector & use the torque app. My XJ doesn't throw any codes. Since its an SE, it had the "idiot lights" cluster. I swapped in a Sport cluster from a junk y2k I bought cheap & double checked to make sure the CEL lit up. I do have to take it back out & remove the hatch ajar light b/c its lit up all the time. Its my understanding that 97 didn't have that option.

I looked into what I would have to do to use the transmission from the y2k & it seems like 98-01 computers are much smarter & have more precise sensors. I'd have to dumb down the wiring & rotor sensor.

Matt_the_Butcher

LOL I really try not to throw parts at a problem before I understand exactly what is wrong with my Jeeps. I've learned a lot & am way more confident about tinkering with them. This forum is a lifesaver!

Matt_the_Butcher

Looks like another NTK o2 upstream sensor will be going into my cart soon.

Dave51

I guess there's worse things to shoot the parts cannon at.

Please post a F/U with that. Quite a few other posters have noted how changing the upstream oxygen sensor corrects that situation, but frankly, I'm not understanding how that could be. After start-up, the engine is in "open loop", and O2 sensor data is not being used.

Torque App should be able to monitor O2 sensor data, perhaps run some waveforms. I have the opposite problem as you, namely, running codes but it runs fine. Here's a sample:



I think some of my issue is that I didn't replace all the sensors at once, and some of it is that my cat is starting to lose efficiency (probably coated with zinc and phosphorous). I get a pile of codes ranging from the 141 to 420.

O2 sensor technology evolved over the years, and for some sensors a flat line at ~0.45 volts for the downstream is normal, so as bad as B1S2 looks that could be actually good.

I was waiting to see what emission testing showed, and last week I passed, so I'm just going to keep resetting the MIL. It usually lasts a week or 2. Mayhaps I shall change the other 2 sensors and cat(s) if fishing gets slow and looking for a research project.

I should post to request to change that sticky about downstream O2 sensors. Mine DOES contribute to engine operation. From the FSM:

Oh right, YOUR thread!

Perhaps your O2 heater is bad, or maybe the jumper affected that (that wire comes off the ASD) or maybe the fuse is blown.

Did fixing the red wire allow you to pull the jumper? That is unclear to me.

Matt_the_Butcher

I am jumper free. I'll let you know if the o2 sensor replacement changes anything. I've read that only Mopar and NTK sensors work for Jeeps and in my experience that is true. I bought a "NGK" knock off from Amazon for my wife's XJ & it lasted about 3 wks. Feel free to share any info you've got, it doesn't hurt my feelings at all.