Someone on CC sold the J E E P lettering for our MJs in plain and reflective tape. I think it was something like "JeepStickers.com" or "JeepSticker.com" but neither of those come up in an internet search. (There is a ".biz" site, but that is not the one I remember.)
I wouldn't trust the gauge. My gauge seldom gets up to 180*.
Is it running in closed loop?
Look at www.nickintimedesign.com for the REM diagnostic tool. This will give a more accurate engine temp reading.
(The RENIX Jeep has three separate temp sensors. One sends a signal to the gauge. It is located on the rear of the driver's side head. The second sends a signal to the ECU for engine/fuel control. It is located on the driver's side of the engine block, below the manifolds. The third controls the e-fan. It screws in to the driver's side radiator. It turns on the e-fan when it detects the coolant temp reaches a preset temp.)
What "secondary sensor along the fuel line" was the issue? I've only own my MJ since 1987, so I am not aware any sensors along the fuel line, primary or secondary.
Also, complete your profile: Yr, engine, etc.
If you want, give your location (city, state [Provence]), if another CC member is close to you, maybe they could help.
With a helper, get underneath it. Look at the tcase shifter linkage. Have your helper shift the tcase from above. Look for loose or worn parts.
Its seems odd that you can get 4L but not 4H. You have to shift past 4H to get to 4L. If that is true for yours, then the internal shift forks may not be properly aligned or broken. The NP231 is a very strong tcase and easily serviceable. If you are confident of your mechanical skills, you can rebuild it. If not, watch a bunch of Youtube videos on rebuilding one. Matt at BleepinJeep has at least one. Search YT for more.
First:
We need more info about your truck: engine, trans, does it still have the Central Axle Disconnect, what modifications were done by you or a previous owner....
Second:
Why did you revive an 11 year old thread? You should have started a new one.
Rec'd a sales ad from RA for close out parts for MJs. One of the parts is a grill. The picture is a 10 slot grill.
https://www.rockauto.com/en/moreinfo.php?pk=682815&cc=1181483&pt=1384&jsn=__GIP__7__&_nck=8LVLUxTaILBT%2BtLxkg8%2B3F88AqnCiBbuZcsuKY0by4KHNpYnxk%2B6vuscn3gvz8TpT1DIbUdPizJDcEwypy6uFEZaEeZQrfl5UhltfMOrEQLFCE4b%2FDY%2FPE9x1Kne8Q3Ush9SHk7uGpZuZH7AKt7Bgxvnv06%2FPsC9pTFoBLG0Cfo%3D
I’ll say it before anyone else: perform Cruiser’s Renix tips first. Next, purchase Nickintimedesign’s Renix Engine Monitor (REM).
the idle is to high. It should be ~750rpm. Probably a vacuum leak. Check all hoses and tighten the manifold bolts.
Running rich maybe from prior vacuum leaks. The ECU may need to adjust the fuel trim.
The REM will help identify other issues with the engine components operation
There is a "C" clip on the shaft. Remove that clip. That will allow you to spread the counters apart. You can then rotate the counter to the proper numbers - one at a time. When done, you put the clip back on and reinstall everything.