Diablosport Predator

I own a 98 Mustang GT with minimal mods and have a Predator tuner, I run Exxon 91 octane fuel. The Predator tool comes with tunes for 93 octane (written for a minimum 91 octane) and 87 octane. When I run the 93 octane tune (even adjusting the spark retard) it runs terrible, flat, no acceleration, and terrible gas mileage. But, when I run the 87 tune (adjusting the spark retard upward) it runs much better with better gas mileage. I live in Utah so I don't know if altitude is an issue, but anyone have any idea why this may be the case? Seems illogical to me unless there is a mechanical issue, or perhaps quality of gas??

Thanks...

ToplessStang said:

Do you have the latest frimware installed in your Diablo? After quite a few years of waiting there is finally an update.

Try that or you can post your question here

Diablo Sport - ModularFords.com

The Diablo guys answer pretty quick.

Click to expand...

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I am on the most current version, performance on the old version was actually better. I'm inclined to think its a mechanical problem, but I don't know what, my mechanic can't find anything and says the car feels fine to him on test drive. But...I know it's just not quite right. I've posted the question one the Diablo website, first go round all they said was that it sounded like "bad gas" (I know the feeling!!!), but I've run three tanks of Exxon through it with no change.