Calibrated MPG display

[crgator]

Went into Engineering Mode a couple of weeks ago, and calibrated the MPG display. I filled up yesterday, and, after months of calculated mpg being about 2.5 mpg, it came in at a difference of about 1 mpg. When I adjusted, I already had about 150 miles on the tank of gas, so I'll see how far off it is on my next fill-up. I'll decide then if I want to make any further adjustments. I've never had a vehicle that the calculated mileage comes within 1.5 to 2 miles of what the dash shows, and I guess it really doesn't matter a lot. It's just that when it's reading 42 mpg, I like to know that's what it is. I might add, it was a pretty easy job.

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[K5Blazer]

Good info.

I manually calculated my mpg for about the first 15 fill ups and compared it to the mpg display number.
My computer estimate was within 1-2 mpg, sometimes higher, sometimes lower, to my manual figures. Often is was almost dead on.

The mpg display was so close most of the time I quit ciphering manually.

I have had a couple cars that had pretty accurate readings. It surprises me when I read how many people don’t seem to have particularly dependable dash readout figures.

 

[realshelby]

I am "experimenting" with adjusting the calibration on my Hybrid now. First fill up after calibration I was actually getting better real world mileage than display showed. Made an adjustment and will see what the second tank does. Not after perfection. But would like to see if I can get it under 1 mpg on most fill ups when comparing. Then I won't have to do the manual check just to satisfy my curiosity every time...

 

[GPSMan]

A few of us find setting the offset to 950/1000 is an accurate setting.

5% adjustment down.

 

[crgator]

A few of us find setting the offset to 950/1000 is an accurate setting.

5% adjustment down.

I don't recall where I set mine, but I think it was 965, and I figured I'd have to go down a bit more. I'll see after this tank. I'll keep the 950 in mind.

 

[MaveRichard]

950 is the number, at least for my truck and a few others.

…unless you are using remote start in a manner that is causing the ICE to run (cold weather, low HVB charge). Because the trip computer is not “awake” during a remote start cycle, it does not accurately factor this fuel used into MPG calculations. I can watch the accuracy go down even from 1 or 2 remote start sessions in a full tank.

I have around 5 tankfuls within .1 mpg accuracy since adjusting this

 

[Terry52]

Went into Engineering Mode a couple of weeks ago, and calibrated the MPG display. I filled up yesterday, and, after months of calculated mpg being about 2.5 mpg, it came in at a difference of about 1 mpg. When I adjusted, I already had about 150 miles on the tank of gas, so I'll see how far off it is on my next fill-up. I'll decide then if I want to make any further adjustments. I've never had a vehicle that the calculated mileage comes within 1.5 to 2 miles of what the dash shows, and I guess it really doesn't matter a lot. It's just that when it's reading 42 mpg, I like to know that's what it is. I might add, it was a pretty easy job.

When you say you went to Engineering Mode, what do you mean?

 

[MaveRichard]

When you say you went to Engineering Mode, what do you mean?

Start with the truck off and door closed. Hold down “OK” on the steering wheel for ~10 seconds while you turn key to “RUN” without actually starting the truck. Let off of the OK button when you see “ET” in green on the dash. This stands for “Engineering Test” mode.

You can scroll through options until you see something like “AFE Bias”. This is the value that we are changing.

If you have a Lariat it is similar - you just press the start button without your foot on the brake.

Hopefully I am explaining this in a way that makes sense…

 

[Terry52]

Went into Engineering Mode a couple of weeks ago, and calibrated the MPG display. I filled up yesterday, and, after months of calculated mpg being about 2.5 mpg, it came in at a difference of about 1 mpg. When I adjusted, I already had about 150 miles on the tank of gas, so I'll see how far off it is on my next fill-up. I'll decide then if I want to make any further adjustments. I've never had a vehicle that the calculated mileage comes within 1.5 to 2 miles of what the dash shows, and I guess it really doesn't matter a lot. It's just that when it's reading 42 mpg, I like to know that's what it is. I might add, it was a pretty easy job.

Thanks very much for your explanation, very clear. I will need to do this because I generally read about 2 mpg more than the actual mileage. That is based filling up and counting against total mileage. Appreciate your comments

 

[crgator]

Thanks very much for your explanation, very clear. I will need to do this because I generally read about 2 mpg more than the actual mileage. That is based filling up and counting against total mileage. Appreciate your comments

Actually, MaveRichard beat me to the explanation, so you owe him the thanks. Try setting it somewhere around 950. I've read that number before. I set mine to 965 (I think) and will revisit after this tank of gas if needed.

 

[Timothyd]

Good info.

I manually calculated my mpg for about the first 15 fill ups and compared it to the mpg display number.
My computer estimate was within 1-2 mpg, sometimes higher, sometimes lower, to my manual figures. Often is was almost dead on.

The mpg display was so close most of the time I quit ciphering manually.

I have had a couple cars that had pretty accurate readings. It surprises me when I read how many people don’t seem to have particularly dependable dash readout figures.

Same for me.

 

[TheSEARCH]

I am only on third tank but its been pretty close to right for me. Maybe its because I have a big kayak on the roof its more accurate?

 

[Eagle11]

I just changed mine to 950, I saw a lot of interesting things in ET mode, is there a thread that explains what is in there?

 

[GPSMan]

I just changed mine to 950, I saw a lot of interesting things in ET mode, is there a thread that explains what is in there?

Except for the fuel economy calculation, the rest is informational only. Nothing else is user "adjustable".

 

[Bill Quattlebaum]

My mpg has been over by about two mpg for the first 3,000 miles. When I checked it today it was off by 3mpg. I need to adjust this, but can't get to the right screen. I can get to the eng. test screen, but not to the adjustment screen. Not sure what I am doing wrong. Thanks for any help. Seems the arrow keys aren't working for me.

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