I know highway mode is normally not set in the factory bin. Has anyone used this setting? If so what did you think? How was the gas mileage and basic overall drive?

 

i haven't made too many other changes to my chip, mostly just minor things like correct the speed reading the ECM sees, lowered the fan temps, dropped the idle speed, some small changes to VE & timing in a few places, & some changes to the TCC.

when i turned highway mode on in my car i picked up around 2 miles a gallon on the highway with it.
with out my laptop running i never know if it is in highway mode or not.

 

I did a lot of work and experimenting with HM. But, before you do ANYTHING, you must get your eprom tuned properly for your engine. Without a proper tune, HM is not all that effective and may even decrease gas mileage.

With a proper tune and LOTS of experimenting, I was getting 30 US MPGs with my (then) basically stock L98. Before that, I was lucky to get 24 US MPGs (on a level highway).

 

Ok thanks. I haven't changed much either. I do have the car running pretty decent, except for a little roughness at idle. My car runs nice at cruise so I was wondering what would happen if I turned on highway mode, how it would act.

 

I have never had much luck with it on my own cars :-( Doesnt stop me from trying :-) Actually utilized it on a 250 mile trip this weekend, havent refilled her yet to do mileage calcs.

Glenn wrote a routine to make the factory setup work much nicer. Its also located in the stickies up top for easy viewing satisfaction

I also have a routine that was made with great assistance from a friend :-)

It may or may not help you, but getting everything tuned and in good working mechanical/elecrtrical order is a prerequisite for running lean.

later
Jeremy