1994 1500 5.9

So I replaced my 195* T-Stat with a 180*
My fuel milage is worse also my idle is lower by 200-400 rpm after wram up. Is this normal ? I thought I have been reading Milage gets better
Took a trip to the bay area, drove a steady 70 MPH,
RPM's where 2000 - 2100
I'm down to 11 MPG. HWY :bawl:

 

Put the 195 back in. Disconnect the battery while you are doing so.

Engine should idle around 600 RPM or so when fully warmed.

 

Why did you switch it out in the first place? Is your engine pinging?

 

Engine was running perfect.
I changed because I read so many posts that the 180* was better for the 5.9, that the 180* is what the engine was originally designed to run and that the 195* actually makes them run hotter than they should and the 180* would help fuel milage.

 

It's been suggested here that you should switch to a 180* Tstat if running a tune, like an SCT Tune from Hemifever.

For basic stock use, the 195* should be fine.

 

No Tuner since it is a 94, no tuners available.
Mods are Headers, 3" Cat back, flow masters and 14X3 Air Filter

No Pinging

 

The PCM EXPECTS a 195 degree thermostat. If it doesn't have one, the PCM sees the engine as running "too cool", and it will compensate for that, in an effort to maintain power, and get the temp up where it should be. Put the 195 degree stat back in. That's what it is programmed to want.

 

Thanks
Will do

 

I had a 180* stat fr awhile. Only put it in for my plow and planned on getting an SCT. I took it out cuz I wanted the heat and put a 192* back in. After the 192* I noticed my truck runs a bit better when accelerating. Unless I HAVE to go back for the SCT when I get it, I'm sticking with the 192*.

 

A great thread to learn about the 180 tstat.

(shush it HeyYou)