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Cooler thermostat

774 views 3 replies 1 participant last post by  WILL 
G
#1 ·
A question on changing the thermostat to a cooler one on a 99 TJ 4.0L automatic. The factory spec. is 210 degrees. I was considering going to a 180-degree type. It seems a lot of people are divided on this as the computer is calibrated to work with the hotter, and by using a cooler you can effectively change performance characteristics. Can you affect your mileage or emissions with the cooler type (check Eng. light goes on)? Is it recommended? And has anyone used this range with this Eng? Thanks in advance for the info.

 
G
#2 ·
What is your rationale for going to a lower temp thermostat? On my CJ, someone had swapped in a 160 degree thermo. I noticed a huge change in driveability and efficiency by going to a 205 degree...which is the opposite of what many people told me would happen. I don't really understand what the benefit of the change is...enhanced performance by lowering the block temperature? I experienced the exact opposite result.

I Jeep, therefore I am.
 
G
#3 ·
Your computer will operate in one of two ways; open or closed loop. In the open loop mode, everything gets set to default settings and efficiency drops. The open loop mode occurs when there is a fault in the system that the computer cannot reconcile. The closed loop mode constantly adjusts based on feedback that it gets from sensors in the system. The computer monitors all the signals and keeps your air/fuel ratio and ignition at optimum points for the design of the engine. I am not sure what your computer will compensate for, but the 30 degree difference might be too large for the computer to reconcile and the Jeep may go into open loop and you will lose performance and mileage. I am sure that LEVE can offer better information on this subject.

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