What is the average cooling temp of a 89 xj.

 

Im sure you are asking because what you are seeing seems high. 210 degrees is normal for a Renix(87-90) Cherokee... The temp sensor for the electric fan is set for 210.

Converting from the stock closed cooling system to an open style system can reduce temps a bit, but the motor runs better and gets better MPG when the temps are right around there.

 

Yeah what Whowey said except I think the closed cooling system is just fine if properly maintained.
4.0Ls like to run around 210 -215 degrees. The electrical fan comes on with higher temps but I think it turns on a little lower than 210. I have read that the sensor is set at 197 but I have no real world test to confirm it.
If you have A/C then turning that on will also bring the elictrical fan on too. No matter the temperature. Some people also add an override switch to turn that fan on whenever they want it on.
Hope some of this was helpful.

 

Exactly, mine will run solid at 210 and the fan kicks on at about 215.

 

The sensor is actually set at 210 , you can get a lower degree set sensor (i have one ) I did the open system conversion, bypass on the fan, Lower degree t stat and have a vent hole in hood ( droped 10 degree's on this one ) I still run warmer than I would like but if you go below 180 the computer will go into limp mode and not function correctly. every little bit helps but as stated before the XJ will normally run at 210

 

Limp mode. I know what you mean but never heard it called that before. It is officially called open or closed loop by those into Jeep Renix ECUs. They change from a rich setting at open loop to a more lean(read correctly adjusted) closed loop setting at operating temp.
Here is my Renix Fuel injection link which is PDF and rather large.
http://www.pirate4x4.com/tech/billav...ion_manual.pdf

 

yea for months i tried to get mine to run cooler but it stays right at 215 or so which seems high but ive never had any trouble with it so far.

 

I added Redline's Water wetter to my cooling system after I did a complete flush on my cooling system. I haven't run at 210 yet, even with wheeling in that mud.. But we have had one of the coolest springs in a LONG time...So much for global warming...