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Discussion Starter #1
Sup everyone,

I tried to do a search but couldn't really find the answer to my question. Anyways, my issue is with the mpg calculator in the trip computer. First of all, let me say this is my first vehicle that has this feature. I'm aware that it most likely isn't perfectly accurate, but mine shows me really wonky readings. After a reset of the MPG, it will read fairly accurately for the first month or so. Then, its almost as if every time I shut the car off, and back on again, I gain 2mpg out of nowhere. At one point it was reading up to 45mpg which is obviously not true. I drive 100 miles a day, but its mostly on back country farm roads averaging around 50mph. I drive the car pretty easy most of the time on my commute. I just reset my MPG again the other day, and after the next tank of gas, was only showing about 26.5mpg, but by my calculations, I actually got 28.9mpg on that tank. It just boggles my mind how completely and utterly wrong this thing is. SO, am I the only one that has this issue, or is this fairly common? Its really not a huge deal because I know how to calculate mpg the old fashioned way, but if theres a fix for it, or a way to prevent it from happening, I'm all ears.

Anyone?
 

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Every one is the same...
 

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I have 6k+ since the last reset on my trip meter... reading 29.8MPG. I did a manual one a week ago and I got 29.6 I would say it is pretty darn accurate.

I do a manual one once in a while because some time I don't see the number change between tanks, even if I go drive it hard. then one day it will go from 29 to 27 mpg... drive for "normal" work week and it will go back to 29mpg... i could likely get better because it is all cruising highways but I mess it up by wanting to drive and have fun LOL

I have a 2015 with 30k miles.
 

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Discussion Starter #5
I have 6k+ since the last reset on my trip meter... reading 29.8MPG. I did a manual one a week ago and I got 29.6 I would say it is pretty darn accurate.

I do a manual one once in a while because some time I don't see the number change between tanks, even if I go drive it hard. then one day it will go from 29 to 27 mpg... drive for "normal" work week and it will go back to 29mpg... i could likely get better because it is all cruising highways but I mess it up by wanting to drive and have fun LOL


I have a 2015 with 30k miles.
ok so yours actually works how its supposed to. I wonder why mine acts so weird? I have a 2016 with 8k miles.
 

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ok so yours actually works how its supposed to. I wonder why mine acts so weird? I have a 2016 with 8k miles.
well yes but like I said it isn't instant but maybe it wasn't engineered to be. would have to call up Ford on your lunch break and ask one of the engineers how it "cycles". maybe it does running avg at start up? or only after fill up?

when i do it manually I do it at fill ups, so logically that would make most sense. but doesn't seem to be tried and true.

oh well i rarely look at it.
 

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Discussion Starter #7
well yes but like I said it isn't instant but maybe it wasn't engineered to be. would have to call up Ford on your lunch break and ask one of the engineers how it "cycles". maybe it does running avg at start up? or only after fill up?

when i do it manually I do it at fill ups, so logically that would make most sense. but doesn't seem to be tried and true.

oh well i rarely look at it.
I understand its not instant mpg. thats a different reading. My issue is that its telling me I'm getting 45mpg and I know I'm nowhere near getting that. It hits a point where it magically goes up 2mpg every time I start the car until I reset it. Then it seems fairly normal for a few weeks, and the cycle just keeps going.
 

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I've never done mine manual but it doesn't bother me, tank is getting empty fill it and drive again until going empty, refill and repeat.
 

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I have tracked both, yeah one of those, for 4 years and it averages out to the same

Edit - the average over 4 years is the same value but it is rarely the exact same number. I reset at every fill up
 

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Can someone do a test for me? In the new Mustang, if you go into engineering mode you can adjust the MPG by editing the AFE value in that menu. To get to it, you hold the OK button on the steering wheel while you turn on the car. You cycle through the test screens with up and down and can edit some parameters with left, right and OK. If you have an AFE screen, you can edit it to be more accurate. I don't have an ST anymore to try with but if you have this screen, report back and I will tell you how to edit it. I know you can get into engineering mode on the Focus with the same method, just not sure you have all the same screens as I do.
 

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Discussion Starter #12
Can someone do a test for me? In the new Mustang, if you go into engineering mode you can adjust the MPG by editing the AFE value in that menu. To get to it, you hold the OK button on the steering wheel while you turn on the car. You cycle through the test screens with up and down and can edit some parameters with left, right and OK. If you have an AFE screen, you can edit it to be more accurate. I don't have an ST anymore to try with but if you have this screen, report back and I will tell you how to edit it. I know you can get into engineering mode on the Focus with the same method, just not sure you have all the same screens as I do.
ill try next time im in the car, thanks.
 

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ill try next time im in the car, thanks.
I should also mention so you don't freak out trying to get out of engineering mode, when you are done just turn the car off and the next start will go back to normal mode.
 

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I don't pay a lot of attention to my fuel economy because most of my driving is city miles and I have fun when I drive, so I'd just be disappointed anyway. Out of sight, out of mind.
 

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I have a 15 F250, my 16 ST, the wife's Expedition and I reset the fuel mpg every single fillup and manually check mpg every fillup on all of them. On all 3 vehicles and every other Ford (10 Fusion, 12 Focus, 08 F150......) that I've had that I can think of have all been 1 mpg off +/- at each fillup. It's sort of a guide...
 

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My 2012 SE was usually pessimistic by about 2 mpg, the ST is optimistic about the same. I reset at every fill up. FWIW, the SE averaged around 35 lifetime (cut short by a Camry at 204k miles) and the ST is averaging around 29 at 13k. Never had the numbers way off, probably the biggest delta in either car was less than 4 mpg.
 
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