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Hi everyone, i have a 98 Jeep xj with 65xxx miles on it. It’s the base model with only dummy lights on the dash so it makes problems a little harder to diagnose. Anytime I’m off-roading or driving for a while and the Jeep starts to get hot the oil light comes on and the idle starts to go up and down a little. I had the idle sputter problem when i first got it but i changed the plugs, wires, distributor cap and rotor. I was thinking it could have to do with the minor fuel leak in the line by the tank but that wouldn’t explain the oil light. Anyways i let it sit for 5 min with the hood popped and it would always run like new again. However yesterday i changed my upstream O2 sensor and now almost anytime i stop or am at idle it starts to fluctuate without the oil light coming on. Wondering if anyone would know where to start. Gonna change the fuel lines today after work.
 

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Did you use synthetic oil? Synthetic oil is thinner that conventional oil.

As a general rule of thumb, when you change electronic sensors you should reset the ECM (Engine control monitor) aka computer. This will reset all the parameters the ECM has learned, to factory default. It will then recognize the range of the new sensors and adjust accordingly. Putting in a new O2 sensor, the ECM will operate based on the old sensor. As sensors get old and wear out, their efficiency decreases, and the ECM compensates for this. Put in a new sensors and it confuses the ECM. It's easy to reset the ECM. Pull the battery cables off the battery, use caution. Touch the cables together for about 30 seconds. Then reattach. This will drain the capacitors in the ECM and reset to factory default. It may take 1/2 a tank of fuel till the ECM adjust to all the sensors. Good luck
 

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You can go to a junk yard, and get a dash with gauges and install it. You will need to replace the temp and oil pressure sensors.
 

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Discussion Starter #4
Did you use synthetic oil? Synthetic oil is thinner that conventional oil.

As a general rule of thumb, when you change electronic sensors you should reset the ECM (Engine control monitor) aka computer. This will reset all the parameters the ECM has learned, to factory default. It will then recognize the range of the new sensors and adjust accordingly. Putting in a new O2 sensor, the ECM will operate based on the old sensor. As sensors get old and wear out, their efficiency decreases, and the ECM compensates for this. Put in a new sensors and it confuses the ECM. It's easy to reset the ECM. Pull the battery cables off the battery, use caution. Touch the cables together for about 30 seconds. Then reattach. This will drain the capacitors in the ECM and reset to factory default. It may take 1/2 a tank of fuel till the ECM adjust to all the sensors. Good luck
Thanks, i drained the Ecm and now I’m getting a transmission sending unit code on the dash and it still idles weird when cold. Gonna clean the fuel system next and swap that cracked line
 
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