160 thermostat...bad gas mileage?????

[BobCarter]

I recently about a month ago installed a 160 thermostat in my 5.0 and as of the last two weeks seem to be getting really bad gas mileage. I haven't tested it, but like...maybe as low as 10-11? could this be from the therm? I've put 180 degree thermo's in my mustang and other cars before with nothing but positive advantages. is 160 too cold? thanks

 

[expo5.0]

i've gotten some ok mileage numbers with a 160 in my 5.0. granted not all the time, but if i try i can get int he upper teens on the highway consistently and around 14 in town. i did the stat witha bunch of other mods though, so it is very possible that on its own it could hurt mileage.

 

[Robert]

Very likely the thermostat. Your computer will run in open loop mode until the temperature gets to the temperature that was preset by Ford. That is about 190F. When you are in open loop, you are running a lot richer than it does once it switches to closed loop. It runs richer by dumping extra gas into the cylinders which reduces mileage and increases emissions. I am not certain, but I believe it helps the engine warm up quicker that way. When you get an aftermarket chip that requires a lower temperature thermostat, it lowers the temperature that the engine switches to closed loop thereby getting increased performance. Without a chip that makes use of your thermostat, your mileage will suffer.

Ideally you should get a chip that opens at the bottom threshold for going into closed loop. If by chance Ford sets it at 180F, then that would be the thermostat to try. I do not know what temperature that would be but I do know that mine maintains 192F with the factory thermostat.

 

[james t]

all of this is true. the cold thermostat is an old mustang tuner trick. it makes the computer run richer because the computer thinks the engine hasnt warmed up yet. this extra fuel helps when youve gone with a highflow intake, exhaust, bigger cam, etc. the stat is a necessity when you go with a chip/programmer to curb detonation. but, if your relatively stock, go with a 180. if youre runnin rich on the stock motor, youre gonna get worse milage.