Running in to an annoying issue that I have yet to be able to solve. Just replaced the water pump, thermostat, radiator, upper and lower hoses on my 97 4.0 5 speed XJ and I got a check engine light for code P0118. Temp gauge wasn't going past the first tick mark over 100 so i figured the sensor was bad. I changed out the coolant temp sensor in the thermostat housing and the temp would raise on the gauge and hold a little under 210 (used a 180 degree thermostat) like it is supposed to. I was driving it around town and i noticed the temp gauge would suddenly drop to above 100 and then would bounce back up to regular operating temp. Then the problem that came about was the temp gauge dropping all the way down, the electric fan kicked on, and horrible sputtering until it died. Tried restarting and it would just turn over but wouldn't start. Managed to get it to roll start and made it back home. Replaced the TPS the next day and it ran fine until it started to do the same thing again. I'm lost as to what I need to do next. Could it be that my new temp sensor was faulty?

 

#1: Don't use a 180* thermostat. Use a 195*

#2: Make sure you didn't install the thermostat backwards.

 

Thermostat was installed correctly and functions properly.

 

But it's still the wrong stat
195* Stant Super Stat is a better choice

 

Would the thermostat being the a lower opening temp cause the issues that I am having?

 

You've got an issue with the wiring to the CTS. Probably at the CTS connector or where the wires enter the fuel injector manifold. Examine the wiring at the connector and manifold. Remove the connector and examine the pin cavities for corrosion and/or being pushed back in the connector.


P0118 is high voltage from the ECT. If you remove the ECT connector it will trigger a P0118. Same as having open wires to the ECT sensor.


Thermostat has nothing to do with your issue.

 

That's what I was starting to think. If the connector is the problem, I have a parts car I could rob the ECT connector off of. I wouldn't think that the thermostat has anything to do with such a problem.

 

SOLVED!! Spliced on a new connector for the temp sensor and all is well! Thank you CCKen for pointing me in the right direction.

 

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similar issue on a 96 xj, new t stat about 2 months ago and now it will drop to above 100, the go back up to 195 and drop again... thinking temp sensor?

 

 

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I see Wonders is off his meds again.

 

It tasted awful so I had to stop

 

LOL