383ss

iTrader: (14)

I had my tune perfect with 91 octane gas, as far as VE, ltft and STFT's go. I was going to do PE and KR and I put in some 89 octane 10% ethenol fuel and now my LTFT's are off by about an average of +8

anyone else experienced this? it was off enough to cause a 101 SES light.

if I have to I'll just retune it with 89 octane 10% ethenol, but I wish I didn't have to.

Bombguy99z28

In theory, fuel blend shouldn't matter so much for the VE, as VE is a representation of air.

Not sure how that works out in the reality of our cars and blended fuel. Crappy california gas is all I've ever really ran in the car, and I've never seen that big of a difference between blends, even the v-power and other crap they put in them.

HumpinSS

iTrader: (1)

why did you go to 89 gas to tune for power?

383ss

iTrader: (14)

cause 89 10%ethonol is 20 cents a gallon cheaper than 91 and I usually run that. therefore, I thought I should tune to 89.

backpurge

The specific gravities of different fuels effect the air/fuel ratio quite a bit. You can be running 13:1 afr wot with pump gas and 15:1 afr wot with some race gases on the same tune. Be careful.

383ss

iTrader: (14)

that was kinda my thought... ethanol is just basically alcohol, so that is 10% alcohol blend. I don't think its necessarily going to cause a problem, my LTFT's are just way off. maybe I need to find a happy median. Im guessing that is how the factory tune is ???

soundengineer

iTrader: (16)

it also depends on your mixing technique

pump and pour..you might not get a good mixture...leading to inconsistent fueling
mix outside the tank and you can measure better and really truely mix them instead of hoping they mix well in the tank

383ss

iTrader: (14)

its from the pump, no mixing involved. Caseys is the only station in KC that sell it.