MPG Correction Tutorial - AFE Bias Adjustment (via Engineering Test Mode)

[mikeymaverick]

MPG Correction Tutorial
If your Ford Maverick displays an inaccurate MPG, you can correct it by adjusting the AFE bias in Engineering Test Mode. After calculating my truck's MPG at the pump, I discovered the displayed MPG indicated a value approximately 1.2 MPG higher than the actual value (about 4-5%)

Steps
Follow these steps to enter Engineering Test Mode and fine-tune the AFE bias for a more accurate MPG readout.

1. Enter Engineering Test Mode
   • With the truck off, press and hold the right-side OK button on the steering wheel.
   • While holding the OK button, press and release the Start/Stop button (or turn the key to the "on" position). You do not have to start the engine.
   • Continue holding the OK button for 5-7 seconds until you have entered Engineering Test Mode.
2. Adjust the AFE Bias
   • Use the Up/Down buttons to navigate to the AFE Bias option.
   • If you haven't made adjustments yet, the default value will be 1000 (representing 100%).
   • Use the formula or Siri Shortcut below to adjust your AFE bias so your truck displays a more accurate MPG value.
   • Turn the truck off to exit Engineering Test Mode.
3. Bonus Features
   • Engineering Test Mode also provides access to diagnostic trouble codes, RPM, coolant temperature, and other valuable data.

Calculation Formula
Current AFE Bias value X Calculated MPG / Displayed MPG = New AFE Bias Value

Pro Tip
I recommend repeating this process multiple times over a few fill-ups to calculate a more accurate average. When I did the math, I noticed some variance, so taking multiple readings will help you get a more precise result.

Siri Shortcuts
For iPhone users I’ve included a Siri Shortcuts link below that quickly calculates the new AFE bias value, even if the current bias differs from the default value of 1000. This shortcut makes fine-tuning your MPG quicker and easier on the go.

https://www.icloud.com/shortcuts/679729a810094cee9e26bb64b5142c66

Photos
Main Engineering Test Mode Screen

AFE Bias menu.

I have already adjusted mine from 1000 to 950 (100% to 95% readout)

Diagnostic Trouble Code Menu. There are many more menus as well.

Siri Shortcuts app I built.

Hope this helps!

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[riparian]

Outstanding! I love stuff like this. I keep a spread sheet on my phone to calc and record mileage; I've been recording the displayed gas mileage in the notes field, so I should be set to calc the average variance.

 

[inline_five]

I use Fuelly to track mpg. Also set my AFE to 950 as a good best estimate baseline. It's about that when doing the calculations.

Still am getting excellent mpg, I'm at around 36-36.5 highway @ 70 mph sustained and low 40's (average) for around town city driving in normal temperatures. Very pleased.

 

[The Real Maverick]

I use Fuelly to track mpg. Also set my AFE to 950 as a good best estimate baseline. It's about that when doing the calculations.

Still am getting excellent mpg, I'm at around 36-36.5 highway @ 70 mph sustained and low 40's (average) for around town city driving in normal temperatures. Very pleased.

Most people, myself included are happy with the setting at 950 (95%).

No real need to experiment and constantly tweak unless you enjoy that sort of thing.

There is a strong consensus with using 950. They are not (usually) random. Pretty much all the trucks are off by 5%.

I'm sure there's an exception here and there.

 

[SubtlySeismic]

Thank you for sharing this nugget! I don't obsess over my mpg like the hybrid crowd but it's great to know I can calibrate since it's consistently off and a little annoying. I will be giving this a try very soon!

Something I've noticed is that the longer I let it run without resetting, the closer to actual mpg it gets, but I lost interest in tracking after a couple of tanks.

 

[MetalsGeek]

My indicated MPG over many fill-ups averaged 4.4% high so I used an AFE of 958.
Side note: I hold my foot on the brake pedal in addition to the OK button to enter Test Mode.

 

[Mr Maverick]

Amazing , can’t wait to try it!

 

[Phimosis]

Most people, myself included are happy with the setting at 950 (95%).

No real need to experiment and constantly tweak unless you enjoy that sort of thing.

There is a strong consensus with using 950. They are not (usually) random. Pretty much all the trucks are off by 5%.

I'm sure there's an exception here and there.

Pretty much all manufacturers of all models set their software to lie to you about your gas mileage. I’m guessing there is a federal regulation that says the measurement has to be within in 5% margin of error, so they deliberately set it at +5.0%.

 

[cdubbed]

Nice tutorial. 923 is my sweet spot

 

[HeyBales]

FYI - for hybrids you'll likely be chasing a seasonal moving average if you get much hotter or colder temps that drain the HVB more and cause the engine to run more - besides winter with ICE running purely for heat/warmup.

I've observed my summer fine-tuned number 956 is pretty worthless now. I mean still within 5% probably - but my DTE has progressively gotten worse since Aug.
Now I'll cry about my 600 mile tank fillups being gone too.

 

[Ozarkbeard]

Most people, myself included are happy with the setting at 950 (95%).

No real need to experiment and constantly tweak unless you enjoy that sort of thing.

There is a strong consensus with using 950. They are not (usually) random. Pretty much all the trucks are off by 5%.

I'm sure there's an exception here and there.

This is exactly what I did. Fast and easy to do. Originally was 1,000, changed value to 950 (5% lower). Almost spot-on with my at the pump calcs. And no apple product needed.

 

[MCIAD]

I have an Ecoboost Lariat and just could not get into the ETM. My display just scrolled between the Seat belt [OK], Full Accessory Power [OK], and a third I cannot recall while typing this. I tried it with the engine started and not - no dice. I gave up after 1/2 dozen attempts before I really screwed something up.

One of my Forescan to do's is to disable that bloody seat belt warning, just haven't got around to it yet. It just moved up on my priorities list.

 

[Bill Quattlebaum]

This information is spot on. I have adjusted mine several times. Started with 940 and I am now using 952. I like to verify mine about every 1,000 miles. Don't believe the on dash reading unless you have adjusted the AFE bias.

 

[Joe Strummer]

I once did the same to my wife's weighing scales. It did not go down well.

As I am retired, MPG has become a meaningless concept. But I'm guessing this hack does not actually change/improve your MPG, merely tells you what it actually is. But my father would always say "it is what it is".

 

[imboden013]

I once did the same to my wife's weighing scales. It did not go down well.

As I am retired, MPG has become a meaningless concept. But I'm guessing this hack does not actually change/improve your MPG, merely tells you what it actually is. But my father would always say "it is what it is".

I’m not messing with mine either. I’ve sometimes done calculations and sometimes it’s lower and sometimes higher. All sorts of variations that could make it not jive with the truck computer. Also I’ve checked the odometer and it’s off by about 1-2 %. Of course that may not be accurate as the way I’ve checked it is by using mile markers on interstate.

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