Ok guys since i got my Jeep about 2 months ago, its always ran about 160 degrees. This is killing my gas mileage because it never goes into closed loop. Its running really rich. I just replaced the thermostat today with a Failsafe 195 Degree. Still runs the same temp. What else will cause it to run too cool? My gauges are working fine. Maybe the fan?

 

T-stat regulates the temperature. If it is over cooling teh T-stat will just stay closed longer to allow it to heat up. Have you verified your temps with something other than the factory gauge?

 

I havent verified wih anything else. What else wold you recommened using?

 

Take the rad cap off and stick a cooking thermometer in it. Just take the cap off before warming it up!

i.e. meat or candy thermometer should work.

 

Alright then. I work at Harbor Freight so i can get a thermometer for like $1.

 

Get a IR temp gun, they come in really handy for a lot of diagnostic work, like finding out what cylinder is misfiring.

 

Infrared Correct? Yea we got those also, and i was leaning towards getting one of those.

 

Yep, get one.

 

Good idea, Busted! Mine was a dimestore fix.

 

What is your gas mileage?

Could be the temp is correct, but you did not mention what your mileage is.

 

Its maybe 13, havent really calculated but putting 10 dollars doesnt last but maybe 25 miles. It smells horribly rich also. I just put a new O2 Sensor on it about 2 weeks ago and put some new plugs on. I also recently pulled the A/C relay on it so that the compressor isnt constantly running. Would the fan clutch affect anything?

 

Ok guys, i've replaced the Coolant temp sensor and put a new thermostat on and its still running cool. I can let it idle and fully warm up and the coolant is only lukewarm.....wtf?

 

ha, your complaining about running cold, I cant get mine to stop running hot!

 

Something is wrong here. If it were actually running too cool you'd be getting a CEL and it would set a code 17 for "Engine running too cool".

Extracting Fault Codes:
Without ever starting the engine Turn the ignition switch ON, OFF, ON, OFF, ON and observe the CHECK ENGINE LIGHT. The CHECK ENGINE LIGHT should begin to flash a series of codes. The flashes will be separated by short and long pauses. The long pauses separate the "ones" and "tens" positions, and each code from the next. Example: 55 is 5 flashes then a pause, then 5 flashes. A code 55 will be displayed at the end of the test.
On a digital odometer it will be displayed in numerals where the miles are displayed.

Diagnostic Trouble Codes -

11 IGN reference signal. crank sensors
12 Battery input to PCM disconnected during last 50 key starts.
13 Fault in the map sensor pneumatic circuit.
14 Fault in the map sensor electrical circuit.
15 Fault in the vehicle speed sensor circuit.
17 Engine running too cool.
21 Problem in the oxygen feedback circuit.
22 Fault in the coolant temperature sensor circuit.
23 Air temperature sensor.
24 Intake air temp. sensor voltage high.
25 Fault in the IAC motor drive circuit.
27 Fault in injector driver interface circuit.
33 Fault in air conditioning cutout relay circuit.
34 S/C solenoid circuits.
35 Fault in fan relay circuit.
41 Fault in the charging system or no field current.
42 Fault in the ASD relay driver circuit.
44 Battery Temp Voltage.
46 Battery voltage is too high.
47 Battery voltage is too low.
51 Lean condition is indicated.
52 Rich condition is indicated.
53 Internal problem in module.
54 No cam position signal.
55 Completion of fault code display.
62 Unsuccessful attempt to update EMR mileage.
63 Unsuccessful attempt to write to an EEPROM location by the controller. __________________

 

No CEL. Checked the codes the other day, got 12, 33, and 55. 33 because i took the A/C relay out. Aside from that nothing. I'm still stumped.