How To Adjust Your Indicated Average Fuel Economy

[Vlad Soare]

I would agree if the calculation were correct to begin with, and it were getting less and less accurate as time went by and the various components got older and worn out. Or if the calculation were correct for most cars save for the odd exception here and there. But if it's incorrect for all cars, right from the factory, then it must be something else.
Between a real 13 mpg and a displayed 15 mpg there's a 13% deviation. I can't believe that all the fuel injectors in all the Mustangs come from the factory with a 13% deviation from spec. That's impossible. The manufacturing tolerances must be measured in hundredths of a percent (or maybe tenths, if we want to be a little clement). 13% would be disastrous.

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[2015Pumpkin]

As a side note, I just completed my first real highway "road-trip" after three years of ownership. 2100 km in the mountains in Western Canada. Best tank was 8.0 L/100km and worst tank was 8.8 L/100km (29.4 - 26.7 MPG US) I was very impressed. I don't normally get this good fuel economy, as I am usually doing some city driving etc. Speeds were moderate and my right foot was only occasionally heavy. I had recalibrated my economy indicator a couple of years ago. My indicated vs measured on this trip showed an error of between 0 and 2% which is fine by me.

After driving for a couple of tanks like this, my Distance to empty read 725 km! (450 miles) Who knew you could drive a 5.0 this far? Nice considering the relatively small gas tank.

That IS AWESOME!! Hope I can come close to that!!

 

[stangs-R-me]

I adjusted my 2016 following this procedure and finally got around to doing it on my current 2021 101A Ecoboost with standard cluster & Sync 3 w/ 8" touchscreen.

There is no LEFT "OK" button, as the radio controls are now on the left side (LH OK button is now MUTE), but holding down the RIGHT side OK button when hitting the START button got me in the ETM as I had hoped.

Guessing the 200A, 301A, & 400A should be the same.

Had 50 fill-ups to calculate the correction factor which was 95% or 950 ... coincidentally, this was exactly what I needed to correct the 2016 too.

Doug

 

[Buldawg76]

I know this is an older thread but one thing I have not seen mentioned in it yet is just how accurate your odometer is in terms of actual distance driven after reading all 7 pages. Unless you have verified your speedo/odometer is reading the actual speed/distance you are traveling then all calculations made and adjusted AFE numbers will be inaccurate as well.

I worked for Harley in research and development as a durability mechanic for 11 years and I know for a fact that federal regulations by the DOT allow for 8% variance in the accuracy of the speedo/odometer reading which means your recorded speed/mileage could be off by +/- 4% either side of the speed/mileage being shown on your dash.

I have verified my speedo/odometer is dead on at 60 mph with a GPS speed app on my phone and within 0.1 mph at 70 mph.

Unless you have verified your cars speedo/odometer us accurate all your adjustments are also skewed.

BD

 

[Zathras]

Anyone know if customized AFE Bias settings need to be re-done if you lose battery power for a while?

 

[Cav427]

Had a friend who scoffed at a 2019 GT 6 speed getting 36 mpg city, adjusted the AFE bias to 2000. Thank you, I won $100 in the bet.

 

[HoosierDaddy]

Had a friend who scoffed at a 2019 GT 6 speed getting 36 mpg city, adjusted the AFE bias to 2000. Thank you, I won $100 in the bet.

Good one. I won a bet in the early 90s that i could achieve 1G acceleration on the street. Had a G-Analyst (what Mike Vallentine built and sold until his non-compete period ended and he could launch the Valetine One). Just turned the gyroscope box 180 degrees to generate the "proof" trace and laid on the brakes.

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