A little backround.Total stock 08 6.7 6 speed auto pulling 14,000 fifth wheel.Was averaging 10 to 10.5 at 62 mph traveling in the west( combo mountains/flatland).While in Oregon Dealer did flash on overhead? and transmission.Didn't like way trans was acting and you all helped me and told me to have relearn process done.That fixed shift pattern problem.Now traveling mid west heading east( mostly flat) and can get no better than 9.This is all hand calc.Did they mess something up or is there maybe another problem?(deletes are out of question for now).Coming back across Colorado mountains didn't seem to have as much power as when I went to Oregon.Truck only has 17,000 miles on it.

 

You can pull the plug on the EGR valve. I improved fuel mileage by over 2 mpg . Towing a 11m lb 5th wheel I get 11.5 - 12 mpg.

 

What do you mean by unplugging EGR valve.Is this an electrical plug? What about cel's by doing that.

 

There is a brown electrical connector on the EGR motor on top the intake. Just unplug it. You will get a CEL and it will be passive and not derrate your truck. You will see better MPG. You can plug it back in if you want or need to and reset the code with a cheap scanner tool or it may even fix itself (the CEL) after a certain amount of restarts after plugging it back in... Nothing detrimental here. Worth the MGP increase.

 

Is there anyway to fool by bypassing or shorting things

 

Your loss in mpg could also be unrelated to anything other then a dirty fuel filter. Even if it was changed recently, you may have picked up some fuel on your trip that may not have been real clean. Been there and done that a few times.

Deletes netted me a solid 40% improvement on my mpg on my 07.5 6.7.
Newer trucks may not see as good of an improvement because of their current factory programming which would give them better mpg then earlier trucks.

Many variables can effect mileage. Grades, crosswinds, tire pressure, 5 mph difference on the go pedal, leaking intercooler clamps under load etc etc.

I enjoy eeking out the best mpg I can get by addressing all of the above and quite often I get a positive result. Even the air filter on these becomes very retrictive very easily.

Scotty

 

Thanks for the answers,been without internet so could not reply until now.