[Volasko]

Has anyone with an AA tune noticed a difference between what your computer estimates as your average fuel economy vs actual fuel economy calculated by hand? Last fill up I calculated my fuel economy (km's vs. gas used since last fill up, in mpg) and compared it to what my computer estimated since I reset it last fill up. What I had calculated was 3-4 mpg less than what my computer said. Is this common or have to do with the AA tune and the throttle remap?

[fdriller9]

Originally Posted by Volasko

Has anyone with an AA tune noticed a difference between what your computer estimates as your average fuel economy vs actual fuel economy calculated by hand? Last fill up I calculated my fuel economy (km's vs. gas used since last fill up, in mpg) and compared it to what my computer estimated since I reset it last fill up. What I had calculated was 3-4 mpg less than what my computer said. Is this common or have to do with the AA tune and the throttle remap?

From the looks of what you typed your comparing km with miles. You're probably not but it looks that way.

The mpg in our cars is an average of multiple fill ups. It is an average off all the gas that has been run through your car from the last reset. Ie disconnecting the battery.

[Volasko]

I am a mechanical engineer, I can ensure the math is correct. I also reset the fuel consumption average at time of my fill up.

[e90pilot]

The MPG calculation is not an actual measure of gas mileage. I'm not sure why since the car has a fuel counter and odometer. It uses a combination of engine load, throttle position, etc to give you an estimate. It's possible that changing the fuel mapping would decrease the accuracy of the mpg calculation since the tune uses a higher fuel/air mixture.

[CombatNinja]

My computer has always been inaccurate, off by 1.5-3 mpg before and after the tune.

[bimmerque]

If before the AA tune you drove like Mrs. Daisy, and still after the AA tune you’re still driving like Mrs. Daisy, then you should get a small increase in your fuel economy. But, if you drive like a bat out of hell, like I do, then your fuel economy sucks Orangutan balls!! So it pretty much depends on which side of the balls you’re sucking! It’s a no win stuation…

[Francis M.]

I've also done Manual calculations vs what the computer suggested average.

My calculations have always been within 1MPG of what the comp states....
I'm guessing the variance is due to me filling up more than the last time.. Extra clicks on the top off maybe?
I thought the newer cars based the calculation on speed vs fuel flowing out of the injectors?

[ZZZZ]

a side effect of an aa tune is a heavier right foot which in turn causes higher fuel consumption. the miles left to empty is not resettable like the average fuel consumption and takes into account the driving style in a longer period of time.

keep in mind that in Toronto we have switched over to winter fuels around 3-4 weeks ago which are notorious for higher fuel consumption, it will take a while for the computer to adjust to the new settings and fuel.

[Volasko]

I just added 40 L and did another calculation. My calculated average was 26.5 MPG vs. 28 MPG my computer was showing. I reset the average fuel consumption the last time I filled up so it is a little bit closer.

[monkey_wrench]

Originally Posted by Volasko

I am a mechanical engineer, I can ensure the math is correct. I also reset the fuel consumption average at time of my fill up.

Mmmmm mechanical engineers don't make miscalculations...