How hot is too hot?

Fouledplugs said:
Well with just a PO135 present the ECM is going to be running in open loop. Meaning the ECM is not accepting O2 sensor data to add fuel or take away fuel to the engine. (adjusting short term and long term fuel trim) When the engine is ignoring O2 sensors it is undoubtedly running very rich.

Properly diagnosing thr O2 sensors would be my place to start and then move into the running hot issue.

You dont drive this everyday do you?
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No sir it's not my daily. So far I've not had the confidence in it but to take short shake down trips.
Should all 4 O2 sensors be replaced?
 
JoeTheCarGuy said:
No sir it's not my daily. So far I've not had the confidence in it but to take short shake down trips.
Should all 4 O2 sensors be replaced?
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All four of them should be diagnosed. Maybe start with a visual inspection of the wiring and connectors at the ecm and at the O2 sensors.

I would also suggest doing a pressure check on your cooling system.

Just as one of the admins said. Use the correct O2 sensors in the Jeep. Doing otherwise will more than likely cause a repeat of the same issue.
 
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Jeepaholic said:
O2 sensors are cheap. I'd replace them all. My jeep will hold a towel on the grill at idle, is your fan shroud and all the rubber seals around the radiator to grill intact? What Thermostat did you use? 185 is too cold anyways.
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Same here on the towel.
 
Or use a Stant 45359 SuperStat thermostat and a 25160 thermostat gasket. Our Jeeps are picky, but not that picky.

O2 sensors, fuel pumps, radiators, IAC's, wheel balance...there's a whole list of stuff that a TJ is picky about but thermostats aren't really one of them. A good Stant non-failsafe thermostat in 195°F and gasket and you should be good to go. About $11.00 all in.
 
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Could be the thromostat you put it in. But it probably its running in open loop since the PO185 is present in the ECM. So be sure to work on the O2 sensors.

I still think the 02 sensors need to be addressed while also working to fix the cooling system. Also a pressure test.
 
I don't believe the thermostat that I installed is faulty, the Jeep may not like that particular thermostat, but I don't believe it to be defective. It's a Stant, which is a well respected name brand. But nonetheless, I bit the bullet and bought the gold plated Genuine Mopar 195* thermostat and will install it after the engine cools down, hopefully tonight.
While I was at the dealership I did get them to print the connection info for each O2 sensor. In a previous post I asked about an unconnected plug that I have under the hood, I believe it goes to one of my O2 sensors. I have one downstream sensor unplugged as well. With the info from the dealership maybe I can confirm that the connections are correct, then go from there.
 
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Regardless, I think the thermostat is faulty. That's a classIc sign of it sticking. It was stuck partially closed which ran hot and then completely open which is why it ran cold. If you want to know for sure, stick it in a pot of water on the stove and see if and when it opens up. It should open up right before the water boils and then close when the water gets cooler.
 
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He had a 185 T stat installed and it didn't get to 200. Why do ppl think it's faulty?

I wouldn't expect engine to get to 200 with a 185 tstat on a short drive in mild conditions.

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I would expect it to be faulty because a 195 runs the engine around 210ish. A 185 should get it up to a solid 200ish and since the thermostat controls the minimum operating temp and the radiator controls the max, not reaching 200ish indicates that the thermostat is stuck open and letting the radiator overcool the system.
 
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