inaccurate MPG
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Tuned
Joined: Apr 2011
Posts: 356
Likes: 77
From: Fayetteville, NC
inaccurate MPG
This is great information for those of you who care. I "stole it" off the f-150 forum but I just tried it on my 2022 F-350, and it works. Here's the post.
The LOM is known to be pretty inaccurate for most of us. The good news is that you can fix it quickly and easily in 2 minutes with no tools if you know roughly how far off it normally is...
This was posted on another forum, but I thought it was too helpful not to share. Note, I used it for the 8" display size and it worked perfectly. I modified the procedure to be more clear than what was posted on the other forum. I have not tried the 4.2" display procedure because I don't have that one. I did this and my next fillup was accurate to within 0.1mpg.
FIST!!
Take your hand calculated MPG and divide it by the LOM display MPG....then multiply by 1000. This new number is what you will change the AFE Bias to.
Mine worked out to be 934 because my hand calculation was 18.3mpg and my LOM said 19.6mpg. Example: 18.3/19.6 = .9337xxxx. Multiply by 1000 gave me 934 (I rounded up) as the number to use.
For Lariat and up 8 inch Display:
Engine off.
1. Press and hold OK Button on the left side of the steering wheel and don't release it until the end.
2. Press push start Button only (Not Brake Pedal) to turn to Accessory Mode.
3. Once Message “Accessory Mode” appears.... press the Brake Pedal and turn the Engine on.
4. Engineering Test Mode appears instantly. Release OK button.
5. Scroll to AFE Bias and push OK to change it to the number you calculated. Note, it takes quite a few clicks to get to AFE Bias.
6. Once done, turn off truck and it will update your mpg, including your Trip 1 and Trip 2. You'll see it has changed the next time you start the truck.
Note....quite a few of us have been successful just holding down the OK button, starting the truck, then releasing the OK button once Engineering Mode pops up.
For 4.2 inch Display:
Engine off.
Press and hold OK Button on the left side of the steering Wheel.
Continue holding OK button and start the engine...don't let go of OK button until "Engineering Test Mode" appears.
Go through the menu pressing and releasing OK Button until you reach "AFE Bias 1000" appears.
Press and release Down. Using Left and Right change 1000 to the Number You calculated. Press OK.
To leave Engineering Mode after you are done, just turn the engine off.
The LOM is known to be pretty inaccurate for most of us. The good news is that you can fix it quickly and easily in 2 minutes with no tools if you know roughly how far off it normally is...
This was posted on another forum, but I thought it was too helpful not to share. Note, I used it for the 8" display size and it worked perfectly. I modified the procedure to be more clear than what was posted on the other forum. I have not tried the 4.2" display procedure because I don't have that one. I did this and my next fillup was accurate to within 0.1mpg.
FIST!!
Take your hand calculated MPG and divide it by the LOM display MPG....then multiply by 1000. This new number is what you will change the AFE Bias to.
Mine worked out to be 934 because my hand calculation was 18.3mpg and my LOM said 19.6mpg. Example: 18.3/19.6 = .9337xxxx. Multiply by 1000 gave me 934 (I rounded up) as the number to use.
For Lariat and up 8 inch Display:
Engine off.
1. Press and hold OK Button on the left side of the steering wheel and don't release it until the end.
2. Press push start Button only (Not Brake Pedal) to turn to Accessory Mode.
3. Once Message “Accessory Mode” appears.... press the Brake Pedal and turn the Engine on.
4. Engineering Test Mode appears instantly. Release OK button.
5. Scroll to AFE Bias and push OK to change it to the number you calculated. Note, it takes quite a few clicks to get to AFE Bias.
6. Once done, turn off truck and it will update your mpg, including your Trip 1 and Trip 2. You'll see it has changed the next time you start the truck.
Note....quite a few of us have been successful just holding down the OK button, starting the truck, then releasing the OK button once Engineering Mode pops up.
For 4.2 inch Display:
Engine off.
Press and hold OK Button on the left side of the steering Wheel.
Continue holding OK button and start the engine...don't let go of OK button until "Engineering Test Mode" appears.
Go through the menu pressing and releasing OK Button until you reach "AFE Bias 1000" appears.
Press and release Down. Using Left and Right change 1000 to the Number You calculated. Press OK.
To leave Engineering Mode after you are done, just turn the engine off.
More Turbo
Joined: Dec 2018
Posts: 669
Likes: 179
I set mine to 920 and it seems to be very accurate. There is no need to start the engine. Simply sit in the truck until dash and interior lights go out; press and hold "OK" on left steering wheel followed by holding push button ignition until you see the "ET" light come on in the lower right hand driver information window. Let go of both ok and ignition push button and hit "OK" to acknowledge any yellow screens in the DIC. Once you see the engineering test screen you can push the up arrow on the right hand steering wheel to get to the fuel economy coefficient (AFE 1000).
Lead Driver
Joined: Feb 2022
Posts: 7,958
Likes: 4,039
I did this on my 18 F150, but made it more pessimistic in that the better the MPG the less it shows so that towing MPG is more accurate. It works based on a curve, so unloaded highway MPG, if used to calculate, will show more accurate displays, but towing will be off. If you set to more accurate towing, then highway will be off. Set it so that highway actual is slightly better than displayed, then towing will be much closer to actual by tenths. So if you set it to read 20.5 MPG, truck gets 20.7 actual, then towing will be say 9.8 MPG and actual 9.5 MPG.
That has been one of the handiest mods found so far that didn't need Forscan.
That has been one of the handiest mods found so far that didn't need Forscan.
Lead Driver
Joined: May 2021
Posts: 5,819
Likes: 3,453
From: Uh oh, CA
So, I have kept up with every time I filled up, however, I only recorded the trucks estimated mpg for the last 4 fill ups. When working it out I came up with a pretty wide range:
1. 866
2. 939
3. 958
4. 928
The average of these is 922.75, or 923. I figure some of this may have to do with pretty much every other tank I will also have a regen, so I figure that messes with the mpg too... I haven't done any trips towing to see what it shows. I may just switch that setting when I refill soon so that I can test it out with a fresh tank of fuel. I'll have to record the number though that way if it seems off still I can just go in and change it back to stock.
1. 866
2. 939
3. 958
4. 928
The average of these is 922.75, or 923. I figure some of this may have to do with pretty much every other tank I will also have a regen, so I figure that messes with the mpg too... I haven't done any trips towing to see what it shows. I may just switch that setting when I refill soon so that I can test it out with a fresh tank of fuel. I'll have to record the number though that way if it seems off still I can just go in and change it back to stock.
Logistics Pro
Joined: Apr 2017
Posts: 3,924
Likes: 321
From: Lost in the Ozone....
Over the course of ~30k, mine is off by ~4%. Hand Calculated = 14.95, LOM = 15.6 (Trip 2 values haven't ever been reset). 14.95/15.6 = .958. I haven't updated the AFE Bias but may one day since I have a long term value to apply.
Logistics Pro
Joined: Apr 2000
Posts: 4,334
Likes: 306
From: Mills River
I dialed a 973 bias into our 2019 F-350 several years ago:
https://www.ford-trucks.com/forums/1...l#post18546691
The correction has held up so well that I don’t even think about it anymore.
Safe travels,
Jim / crewzer
https://www.ford-trucks.com/forums/1...l#post18546691
The correction has held up so well that I don’t even think about it anymore.
Safe travels,
Jim / crewzer
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