DFlintstone

10-4...I actually was focusing on it's power supply, And a good time to check that Jeep side ground in the middle as well. Not joking here. Your issue may well be the 02 heater not coming on, and that Jeep side wire needs lot's of stuff to be hot. Those wires from the lower sensors up to where they meet the harness for the injectors often get burnt and mangled. Then it's relay needs to work and be getting power form the fuel pump relay, (I think). With the air box out, left front tire off, and the axle hanging cuz it's jacked at the frame, all that stuff is way easier to get at. Then there, is where you might also back probe that 5V feed from the ECU. (I think it gets 5, unplugged, with only ign on) Dancing around 2.5, plugged in, back-probed, running.

The 02 sensor matters for millage. Its one of the rare things you might change only because it's a question mark. I've heard 60K mentioned. One mpg gain at today's gas prices will take a while to recoup $80 spent. Depending on if you are "knocking around", or Hwy. cruising matters. Me thinks a bad 02 sensor can hammer knocken around MPG. (I like nerden out with my meters). Then I spent the $80!

eb1

Thank you for all the stuff-to-check and how-to details. The heating element resistance test was just a bonus I discovered -- easier to perform, no need to remove tire, etc. Maybe most important: if it fails the resistance check then no need to do the other tests.

So tonight I did the resistance test at the O2 sensor connector and the sensor failed; measured resistance was infinite; time for a new O2 sensor.
And I also understand why folks would just replace the O2 rather than test it -- as you described, it's location makes in-circuit testing a challenge.

eb1

I had to reread my old post to understand why cruiser mentioned new 746 injectors as a possible next step.

Clarification: I did not mean to imply that injector 6 was bad.
For injector 6 I did not attempt to measure the resistance. I had difficulty with the clip so I skipped measuring it. But like the others, I've had no obvious issues and suspect that injector 6 is fine.

When I do get to replacing them the 746s are a likely purchase.

DFlintstone

[QUOTE=eb1;3286350] I had difficulty with the clip so I skipped measuring it. [QUOTE]

I did stumble there, figured it out. Pete is busy on lots of forums...

Your logic supersedes, almost. Yes, just finding the resistance wrong, "cut's to the chase". Still though, you want to check it's ground, 5v, and 12 volt feed on the Jeep side, and changing the O2 or doing anything there can be easy or not..... Your call there. Neat that maybe we found it though!

I was the first "guni-pig" for the 746's on Programbos idea. He might have something, but is mostly providing injectors to other rebuilders now....My thread with testimonials on the 746's here>

https://www.cherokeeforum.com/f2/199...r-swap-163105/

eb1

DF, good 746 thread; the smoothness improvement gets mentioned many times; better mpg seemed to be more variable -- what is your final judgement, about a +1mpg gain? I jumped from there into Salad's Rotella T6 thread -- great read, bring on the tractor oil!

For the O2 sensor:
* I'll definitely check the ground, 5v and 12v this weekend;
* Ordered a Bosch O2 from Rock Auto that could get here by the weekend;
* Gotta find my O2 socket!

DFlintstone

Freedgrs tip, just cut the wires so a 7/8 box wrench will fit. Then you don't ape the new one in. My NTK had instructions, something like "finger tight then n/3 of a turn...

On the mileage, a little tough to be exact, but I'll say the really low, 10.5, 11.5 that could happen w/short trips, yarding logs, noodling around with the trailer gathering firewood, those came way up. Now maybe 15-16 there. Hwy miles came up, but not as much. 6 hrs of hwy 101 from Oregon to Santa Rosa is hilly with towns and windy stretches up around 24 at least once. Now I'm getting confused...went from 703's to 746's in there somewhere. Also we don't know if your 02 sensor is working after it heats up, I think the heater just gets it there faster, but I really don't know.

cruiser54

I've never needed a socket to remove a Renix O2 sensor. Open end wrench from underneath.

I woulda waited for an NTK O2 sensor over bosch....

eb1

Thanks for the O2 install tips; I'll go w/ finger tight plus 1/3 of a turn w/ an open end wrench.

Bosch vs NTK? My experience is pretty limited; I don't remember what brand I put on last time but I'll check it when I remove it; I'm guessing Bosch. Dealer installed a new O2 for me in '95 at 56k miles; then I put one in at 105k miles in '02; bought that one from the dealer parts dept. The XJ is at 167K miles now, so it looks like I get about 50-60k miles between (OEM/Bosch?) O2 sensor changes. Was Bosch the OEM part being sold through dealers back in the day?

cruiser54

Bosch was not OEM. I believe NTK was.

eb1

Maybe I've been running NTKs and didn't know it. What do you like better about the NTKs?

Just found the receipt from the 2002 O2 purchase -- it's Auto Zone, so not from the dealership parts dept as stated earlier.

DFlintstone

Get this..I remember the NTK literature had so much turning past finger tight for Zirconia 02's and a different suggestion for Titania, and doesn't say which is in the box! I'd need to dig to see which...Zirconia I think without looking. The idea might be to have something facing a certain way.

Dyslexia/ADD, and computer issues have me

cruiser54

NTKs are a part of NGK and they work better. Flintstone is gonna have a coronary about how tight to tighten them.

You'll feel it. No worries.

DFlintstone

Saving that coronary for matching the splines onto the steering column while holding the replacement steering box up. Ugly task

cruiser54

Not a problem. Easier than you think.

DFlintstone

That's nice to know. My strength and patience wears out within 15 minutes. I'll get it done tonight...third time back at it right now, set up better light, fingers crossed, pinch bolt handy.