91 octane tune

[Dawiz]

2004 Ford F150 FX4 5.4L
DP# U7151

I'm running the 91 octane tune on 89. The truck seems to be doing just fine. Should I make any adjustments or leave as is. The 91 tune is the mid grade tune on the U7151 and in my area 89 is the mid grade fuel. So I'm not sure what to do really. Thank you.........

[mikel]

Honestly, I would use the 87 tune to be safe, and then just use 87 octane fuel to save a few bucks.

The 91 tune is not so much a mid-grade tune as it is the high octane tune for those who do not have access to 93 octane.

Thanks

[Dawiz]

Right now I've got a full tank of 89. Any problems with switching down to the 87 now or should I just put the stock tune back in until I run dry.

[christina]

You can go ahead and switch to the 87 tune now.