Crawling under my 91 XJ and I noticed this piece was broken off, with an empty square/round plug connector dangling next to it. After searching around I'm coming to the conclusion that this is my Coolant Temperature Sensor.....Is this correct? Would this be causing my Jeep to idle pretty fast, i.e. 1700rpm? Also, would it be causing my temp guage to go up and down all the time, because my ECU is enrichening my fuel/air, trying to "warm" up my engine more?

Another reason I'm asking is I thought the CTS was where my thermostat is..unless there are two?

Pic one is dark, more for a reference to where the broken whatever is...these are from under the Jeep looking up, you can see where the exhaust is, two pipes going to one.

Thanks for any help

 

That's not the connector for your coolant temperature sensor.

Your coolant temp sensor is in the water neck where the t-stat is and the sending unit is in the cylinder head, drivers side rear corner.

 

Any idea as to what the broken thing is? Knock sensor?

 

I vote knock sensor.

 

That is the temp sensor for the computer if I'm looking at right. It sould br on the driver side if the block behind the int/exh manifold. Up thats it......

 

x2 knock sensor

 

I don't get any knocking or pinging, just a tick or two from the valves, but my idle is way too fast.

 

You can vote knock sensor all day long but the 91 is an HO motor and there is no knock sensor.

 

From the 1991-1993 parts catalog:

 

I stand stand corrected, but honestly have never seen one on HO motor.

 

What makes you sure it's a HO?

 

He said it a 91.....

 

It's the transition year, i think there were some non HO still manufactured in the first months, anyway according to the double pipe exhaust it's a HO also for me.
They probably dropped the knock sensor in 94.

 

Yep, it is HO. So besides the broken part, let me tell my story from this morning. Driving to job site which is about 25 mins away. Traffic comes to a stand still on the highway, which starts to cause my temp to creep up. It goes up pretty high, about 1/8" from the red, then traffic starts rolling again. I go another 2 miles and it decides to stall. I pull off, let it sit a while, and it finally starts again. Stalls another 1/4 mile away, starts again, finally get it off the highway and I'm pretty close to my job site, about a 10 min walk. No biggie. Work til lunch and head back to see if it'll start. Nothing happens for a while, I'm checking for loose connections etc. Just about to give up, and decide to jiggle my injectors and fuel rail...which to my delight causes the ol girl to fire up again. Got her home, and in the garage, still idling like a bat out of hell tho. I wonder if my fuel pressure regulator is gunked....gonna get this done.

Up to this point I have replaced the following:EDIT:also did Crank Position Sensor; fuel pump, new bosch unit; new fuel filter; plugs; wires; cap n rotor; thermostat; valve for sending coolant to heater core; drained and filled radiator....didn't flush tho, I know, I need to get this done; oil and filter. I think I'm am going to replace the TPS next. The ****ty thing is my odometer is stuck at 212k, and the speedo is broken, but the engine is from a 92, no idea the miles.

 

What did you do the day before to your jeep?