Reversing Redneck wiring 97 XJ SE 4.0 ignition
#16
CF Veteran
Do you have any engine codes?
(1) Cycle the ignition key On - Off - On - Off - On within 5 seconds. (2) After a short pause, the mileage shown on the vehicles digital odometer will be temporarily deleted. After this occurs, read the DTC number displayed on the odometer. Each two–digit number will be displayed with a slight delay between numbers. (3) A DTC number 55 will always be the last code to be displayed. This indicates the end of all stored codes.After code 55 has been displayed, the odometer will return to its normal mode.
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.
#17
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Year: 97
Model: Cherokee (XJ)
Engine: 4.0
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.
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.
#18
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Year: 97
Model: Cherokee (XJ)
Engine: 4.0
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!
#20
CF Veteran
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:
Downstream Sensors (California Emissions): Two downstream sensors are used (1/2 and 2/2). The downstream sensors are located in the exhaust downpipes just after the mini-catalytic convertors. The downstream is also used to determine the correct air fuel ratio. As the oxygen content changes at the downstream the PCM calculates how much air fuel ratio change is required. The PCM then looks at the upstream oxygen sensor voltage and changes fuel delivery until the upstream sensor voltage changes enough to correct the downstream sensor voltage (oxygen content). The downstream oxygen sensors also provide an input to determine mini-catalyst efficiency.
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.
#21
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Year: 97
Model: Cherokee (XJ)
Engine: 4.0
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.
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