Operating Temperature

[ecarlcl]

What's the proper operating temperature for these motors (3.9)? I haven't been able to find a straight answer searching the forum.

My car has been acting like it has a coil going bad for the last couple of months and I've been trying to encourage it to set a DTC by going down a hilly stretch of highway with the cruise set on 60 so I know which cylinder. Last night had my scanner with me and I set it to record real time data thinking I'd catch something. The temperature never gets higher than 190 (I thought just about everything ran at around 210 these days). It never finishes it's emissions cycle. I got a P0125 (Insufficient Coolant Temperature For Closed Loop) but it didn't turn the check engine light on. I think I definitely have a stuck thermostat which makes sense. The heater couldn't keep up when it got really cold back in January. The car has always been really slow to warm up.

If it's not going into closed loop wouldn't it be raising hell with my air fuel ratio and make it run like crap?

I probably still have a bad coil but it's a step in the right direction.

 

[Black LSE]

My 3.9 runs right at 200 on the highway. Crawling in the city it will reach 220, even in cool weather.

 

[ecarlcl]

Sweet. So I am running cool.

 

[joegr]

What's the proper operating temperature for these motors (3.9)? I haven't been able to find a straight answer searching the forum.

...
If it's not going into closed loop wouldn't it be raising hell with my air fuel ratio and make it run like crap?

I probably still have a bad coil but it's a step in the right direction.

Early FI cars didn't go into closed loop until the engine reached full temperature. Your LS like just about all cars of the last 15 or so years goes into closed loop control seconds after you start the engine. The temperature of the [electrically heated] O2 sensors is important for closed loop control, not so much the engine. (The OBD II code description is not correctly worded, it should say that the temperature is too low to complete all of the emissions monitors, not for closed loop control.)

The service manual says that the thermostat should open between 192 and 219 degrees (it's a 195 degree thermostat).
I don't find any indication of what the actual engine temperature range should be. I suspect that info is in the emissions diagnostic manual, which I don't have.

 

[pektel]

My car also took forever to warm up. Thermostat was stuck open. That's how they are designed to fail.

 

[ecarlcl]

Got a new motorcraft O ring and thermostat on the way. I think I'm gonna service the cooling system while I have it apart. This May will be 2 years of ownership so It's about due.