If the air fuel ratio is running rich does that make the exaust hotter?
What is the exaust temp on most truck at 65 with no or little wind. Of course 2wd, 4wd and numerous other factors. What I hope to find out is if my truck is hotter than most at 65 then maybe that explains something about mpg.
What sensors would make the ecm think it was to cool and needed to add fuel to keep the temp right? Maybe a IAT sensor?

 

If you are talking about a diesel there is no real rich and lean. It's always rich at the actual point of ignition, at the injector tip, and too lean to burn out away from that point, near the cylinder wall. In other words there is always an excess of air in the chamber unless the engine is at full power and smoking black. The fuel is not pre-mixed with air to a ratio.

More power and later timing make the exhaust hotter, especially at lower RPM.

I don't remember for sure but I think mine runs at about 600* (pre turbo) on the road at about 65.

John

 

if you are trying to get better fuel milage, the lower you can get egt's at crusing speed the higher the mpg's, this held true for 14 mechanical changes and even worked on program c

 

So if my egts are around 700 then what can be done to change it?

 

700 doesn't sound out of line. Where is your EGT probe mounted? The closer it is to the head, the hotter your readings.

Nick