i believe theres a 180 in mine, it runs cold during winter, theres the zero line and the next one up is where min sits unless im not driving

 

so wut i am hearing is that my gas mileage will greatly improve if i change back to the 195...and flush my cooling system.....correct?

 

I dont understand why your jeep is getting bad gas mileage due to a thermostat, that only controls when the waterpump flows water through the block/motor or whatever. i have a 160 and my jeep runs cooler and seems to get maybe 1mpg better or so. They only came with that thermostat for emissions. sounds like thermostat is not your problem.

 

i mean i see yours is an 88 model jeep but the thermostat should never affect GAS.

 

It can, if the Jeep never warms up to operating temperature it can get stuck in "open loop" and never go into closed loop, that'll cause the Jeep to burn about double the gas it should

 

what does it mean when im getting better gas mileage then?

 

i am just gonna switch it and see wut happens, i mean it only cost like 5 bucks...i will keep you posted

 

I should buy what one tomorrow? 195?

 

This has been discussed many times before, but here you go...

4.0 Liters are designed to run hot. When you first start your 4.0 the computer is in closed loop mode. That means it's feeding a lot more gas in the air/fuel mixture than when the engine hits 195 degrees and the computer kicks into open loop mode.
When it hits open loop mode it cuts back on the fuel in the air/fuel mixture. Therefore leaning the mixture out.
If you don't allow the engine to reach 195+ degrees the computer stays in gas-rich mode (closed loop mode). This will kill fuel economy and pollute the environment more than need be. (Just think how your Jeep exhaust smells when you first start it up, that's the fuel/rich mode).
The auxillary fan (the electric one on the Drivers side) is set to kick in at 217 degrees. It will also kick in whenever the AC is on. The AC compressor kicks on when your in Defrost mode so I believe it kicks on then also, no matter what the engine temp.

Mike

 

It could mean alot of things. theres a bunch of sensors that the PCM gets info from to regulate the amount of fuel to feed the engine, if those start going bad it can also cause you to get worse gas milage. the biggest thing before suspecting sensors is to make sure you're getting up to operating temperature. If the Jeep is running fine otherwise you can assume that you have good spark and its getting plenty of air.




yes, thats what came in them stock.

Great explanation! cept you got open loop and closed loop modes confused. when they first start-up they're in open loop mode and when the O2 sensor heats up is when the Jeep goes into closed loop operation, but if the PCM sees the Jeep running at 160F when it should run at 195F it'll feed the engine extra fuel cause it thinks its still warming up.

 

well my Jeep is getting better gas mileage, is this a freak accident or what??? and when it first starts up you do not smell a rich exhaust smell like u would an old car with a burning rich motor. Should i just replace my thermostat back to the stock 195 thermostat?

 

that is wut i thought....in a much more simple matter but i still thought that. i will switch tomorrow.

 

What kind of mpg are you getting Metalic?

 

If its running fine, your temps are ok and your gas milage is good then leave it alone.

 

bout 16 or so around town when im taking it easy. if im lucky 17 or 18