Colder thermostat vs Gas mileage?

[chanley talon]

I seemed to be running very cold water temps. I was wondering if i install a factory thermostat if this will help my fuel mileage or not?


Thanks for any information.

 

[knochgoon24]

Are you going off the stock gauge? Are you sure the coolant sensor isn't broken. These cars don't run too cool too often.

 

[kthackst]

If your t-stat is stuck open you will get low coolant temps. Our cars run the most efficient when the temp is around 200 degs. Fixing your thermostat should help your fuel mileage a bit.

 

[RipperXX]

I duno If I agree with the wording of the above statement. Depending on your goals...if your after fuel mileage then yea I agree.. But from a performance aspect I like 175-180* So long as your over 175* (at least in a 1g) your fine. But to cold and the ECU wont think the cars ever fully warmed up and wont cycle from open and closed loop operation correctly. Resulting in yes poor fuel mileage and other small issues.

If your cars a 2g, which it looks like it is. I think the ECU looks for a little hotter coolant temp than the 1g does. Which CAN be adjusted with a flash/Link etc. though

If you REALLY want to know, get something you can log with, and or a real temp gauge. You will know if the factory sensor is bad with a logger though cause the readings will be crazy. From my experience you will get a reading like -20*

 

[red92tsi]

I duno If I agree with the wording of the above statement. Depending on your goals...if your after fuel mileage then yea I agree.. But from a performance aspect I like 175-180* So long as your over 175* (at least in a 1g) your fine. But to cold and the ECU wont think the cars ever fully warmed up and wont cycle from open and closed loop operation correctly. Resulting in yes poor fuel mileage and other small issues.

If your cars a 2g, which it looks like it is. I think the ECU looks for a little hotter coolant temp than the 1g does. Which CAN be adjusted with a flash/Link etc. though

If you REALLY want to know, get something you can log with, and or a real temp gauge. You will know if the factory sensor is bad with a logger though cause the readings will be crazy. From my experience you will get a reading like -20*

Im pretty sure a 1g needs a temp of 189 to update your fuel trims.

 

[kthackst]

Every 2g I have been logging in the coolant temp sensor reads 200-215ish. I know the tstats are suppose to be 180 or (170 for a lower temp one) but I have never seen one run consistently run any cooler than 200 for the 180 degree thermostat.

 

[PieEyedPiper]

Nor should it. 180* is the cracking temperature. Fully open is like 193 or something , thus the 200 degree temps.

 

[97gst_spyder]

Mine gets the best mileage at ~200* (around 400-430 miles per tank). But it knocks alot. But after duct work and some other items, I'm at 178-186* now. Lost about 40 miles a tank but no knock at all.

 

[chanley talon]

Well I have not changed the thermostat yet. The car is 1g the photo is small.
I think it has a 160 in it or it is stuck like someone mentioned. I only got like 24 miles per gallon last tank and that was not boosting at all but I do drive on the most hilly windy road to work known to mankind. I think I need to install a hotter thermostat maybe reinstall the EGR valve. Will see I will change it all out and give you my update.

 

[eclipse_16g]

so the 170 degree thermastat that i just ordered is bad thing?

 

[Boostinsideways]

No you should be okay with a 170 degree thermostat. It will crack at 170, but probably wont be fully open until 185+ 1g cars usually run around 180 so you should be good.

 

[Colt4G63 also]

Yeah I run a 170 in my car, but I like to run it cool for track use. The downside is that it will use a little more fuel, the trims don't update unless you hit 186, and with mine I get some idle surge when rolling with the clutch depressed.

When it's really hot out and I use the A/C, it warms up to 200ish anyways, so that saves me fuel during interstate travel. Generally with the A/C off on cool days, it runs a little too cool (175-185), but I like it at 185 at the track.

 

[chanley talon]

Well i got the t-stat out and it was a 180? So i proceeded to press on the top and i could open it with my fingers. So the spring was sprung! Replaced it today so i will see if i makes an improvement tommorrow.

 

[Talon IV]

Dang i wish i could get 24mpg in my talon. But generally speaking you will get your best fuel mileage in a 4 cylinder between 195-215*F, when the ECU switches to closed loop after seeing everything is warmed up and your coolant temp is up and O2 is switching. And generally speaking the colder t-stat may not be hot enough to really get that ECU into closed loop fueling, so in turn you will less mpg's. But this is speaking for a daily driver...