Hey guys I have a 2006 GT with only the MAC axle backs as MOD's. My gas tank when fully filled gave me 290 miles til empty. Then I added the predator 87 octane performance tune and now my miles til empty is 253 miles!!!!!!! WTF happened. Is this normal or is something wrong my my computer. Why would I lose almost 40 miles on a full tank of gas? I apologize ahead of time for my ignorance.

 

Typical results when adding a tuner. I am so tired of these tuners being advertised as improving MPG there is no performance mod that will give you better mileage except for maybe electric fans. Also it looks like you are also now running a larger than stock tire and that will also contribute to a lose of MPG. Also unless you are filling up with the exact same gallons of gas every time then doing the whole MPG from a tank is not going to give accurate mileage. You could very well have used a gallon or tow more than the last fill-up and that is the result. To determine your true mileage rating and if it has changed you need to add total miles driven and divide by gallons of gas added. To many variable to say per tank/fill up. I would also take a guess and say that since you installed the tune you have been hevaier on the go pedal.

Richard

 

do NOT go by what the computer says is left, go by how many actual miles you turn during the course of the tank. the computer thinks it is using a lot more gas now because of the tune, but if you are easy on it, you will see the same mileage as before the tune.

 

and, over the course of a few tanks, the computer will likely average out what you are really using, and the numbers will be more accurate. Calculate the fill up and mileage the old fashioned way. Fill it up, drive a while, fill it back up again, and divide the # of miles driven by the # of gallons you added.

 

I get an easy 19-21 mpg around town with 91 octane tune. I have verified this several times with the ole calulator. The manual calculation is close to my mileage calculator in the car. I do plenty of 0-70 as fast as I can get there. I have seen better mileage around town with my mods. I haven't been on a road trip to see if if it holds. I don't see a CAI in your mods so if you just did the tune you are running richer. Maybe some will chime in that knows the predator tune and can answer that.

 

Im averaging 19-20 with a S/C.

 

I understand what you guys are telling me but shouldn't the "miles to empty" always be the same when the car is completely filled up? When the car is completely full of gas the miles to empty should be the same, it should not fluctuate from 300, 250 or 200! I understand that driving habits will dictate how fast that miles to empty decreases.

 

the miles to empty takes the computer's current mpg into effect, so if that changes, so will your miles to empty. My miles to empty has gone UP while I've been driving before. Just depends on how you use your computer. The more you reset the mpg, the less accurate your miles to empty will be.

 

Dealing with the same issues myself right now, It appears if you don't jump on it every red light you get pretty much the same. Start opening it up more and you will use more. Running 94 octane and getting good milage but if I jump on it and beat it all the time my milage goes to ****. As long as it goes the same distance I dont mind paying more for a gallon, but if I gotta pay more for a gallon plus have it not go as far[&:] I get upset....

 

There is a thread on here about a TSB regarding the tank not filling all the way on some models. That could be your problem. Are you sure you are getting the tank all the way full?