- Jul 26, 2008
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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...
Thanks...