Well i decided i would try out my 89 perf tune yesterday. my low fuel light was on, so i went ahead and filled her up with Shell 89, with a little bit of 87 still in there...Hope this wasnt a stupid move....:o

Anyway, i am doing great so far on mileage, got about 75 miles just below the full mark. (needle usually stay above the F for about 50 miles). It is ok to drive conservative even though you have a Perf tune in, right?? Or does this hurt your mileage, being the truck is kind of tuned to be run a little hard?? I would think so, but correct me if im wrong.....

 

The general rule if you want to switch octane and tunes is to do what you did and wait for gas light to come on then fill and switch. It is okay to drive it conservatively with performance tune. I don't know for sure but don't think there is a huge difference between mileage tune and performance tune.

Kevin

 

yea, the only thing i can think of is timing being different, and maybe the spark curve...i was running my 87 mileage tune, but so far i seem to be getting better mileage with the 89 perf...who knows...

 

Let us know what the difference is. It will be interesting to know what kind of mileage difference there is with different octanes and tunes.

Kevin

 

i know i get better running my 93 tune, its just a can edge for now... hopefuly bill get my tunes done here pretty soon.. i expect my milage to go up even more with the costom tune.

 

A certain tune does not NEED to be driven a certain way.

 

well i did a quick check on the first quarter of a tank w/ 89 perf., and i got 20.3, 79% being hwy @ 65-70 cruise. Not what i was expecting, but still fairly good. But since then driving 85-90% city...OMG!! i will probably cry when i average out the tank....

i will post back though....i might consider springing for a 89 mileage tune, just for the 300 mile trip home....

 

20mpg! when i had my short cab, short bed, 97 4.6l auto i was lucky to see 18-19 on the highway

 

No kidding. I would of loved to get that kind of mileage in my truck.