Just read my codes and code 17 was flashed at me. The code states:

Engine is cold too long:

Engine temperature too high or too low while traveling. Check coolant level, radiator cap, temperature sensor, and thermostat.

The engine light did not illuminate, but the code was recorded. I recently put in a 180 Thermostat when I did the plenum fix and now my truck runs right around 170-180 degrees.

Should this code be something to worry about? Should I put the thermostat back to factory?

 

Some trucks throw that code with the 180 thermostat. Personally, I'd reset the codes and see if it comes back again later. If it comes back again, then I'd replace it with a stock thermostat (195) and see if that makes it go away.

 

i'd leave it be for the summertime, but replace it with a 195 in the fall, before you need heat in the winter.

 

Thanks for the quick replies guys. My question now is running the truck at a lower temp wont effect anything such as the computer changing from CL to OL or vise versa.

 

I ask this because I am currently getting a terrible MPG. Averaging about 9 MPG highway.

 

if your new 180 t-stat is working right, and your engine temp is getting close to 180, then i doubt its affecting mpg very much, nor preventing closed loop.

if you new t-stat is not working right, and your temp is staying around 150-160, then you may be staying in open loop, and that would affect mpg.

a bad front 02 sensor can hammer your mpg.

 

Thanks for the reply. I will watch the temp next time I drive it. If the front o2 is bad, wouldn't a CEL come on? If not, is there any way to test it?

 

test it? not really. you can hook up an expensive scanner tool, or Air-Fuel meter, and read what the 02 is telling the pcm. but if the 02 is lying and misreading the exhaust as lean, and telling the pcm to dump in more fuel, then only your nose or a tail pipe emissions checker can detect the error. The 94/95 is OBD-1, with only one 02 sensor, so it has no double check. 96+ is OBD-2, with two o2 sensors, so its equipped to throw a code.

 

your tstat is probably stuck open; thats what would trigger that code. has nothing to do with what tstat you are running; the problem is its taking to long for the engine to reach its desired running temperature; and yea it'd affect gas mileage.

for the simplicity and cost, i'd just put another tstat in. even another 180 degree.

 

Geez, you guys and the 180º thermostat

Here's an idea -- let 20lbs of air out of your tires and replace it with helium. The helium will cause the truck to lift, hence less drag by gravity on the truck, thereby *increasing* your mileage!