Average Mileage Calculation

[Beachbum]

Can anyone tell me the algorithm used to calculate average mileage and range (I presume the latter is based on the former) on the C14 display? I assume the average mileage is based on a rolling average of the current mileage, but I would like to know the span that is measured (i.e., average of current mileage over previous 1 mile, average of current mileage over previous 50 miles, or ?) and whether it's weighted (i.e., more emphasis on later miles in the range, etc.). Anyone know?

While we're at it, is there any way to occasionally reset the average mileage calculation so that it forgets history and starts with a clean slate?

Thanks for the help.

[maxtog]

Can anyone tell me the algorithm used to calculate average mileage and range (I presume the latter is based on the former) on the C14 display? I assume the average mileage is based on a rolling average of the current mileage

Your assumption is correct

, but I would like to know the span that is measured (i.e., average of current mileage over previous 1 mile, average of current mileage over previous 50 miles, or ?) and whether it's weighted (i.e., more emphasis on later miles in the range, etc.). Anyone know?

I don't think any of us know that.  It is not documented anywhere that I remember reading or seeing.  Your best estimates will come from odometer reading (trip meter- reset it at each fill-up) divided by fill-to-top gallons at the gas pump.

While we're at it, is there any way to occasionally reset the average mileage calculation so that it forgets history and starts with a clean slate?

I thought it would start over "fresh" each time the bike is started, doesn't it?

[tomp]

To reset the average mileage, bring it up on the display and press the top button until the current average mileage disappears, and there are just lines.  After riding a while , the average will start reading again.  I reset at each fill up, and check it just to see how different riding situations change mileage.  Amazing the difference between sustained 65 mph vs riding the snot out of it makes.  My last average city/hiway avg was 41.6 mpg... tomp

[maxtog]

I thought it would start over "fresh" each time the bike is started, doesn't it?

Answering my own question from the manual, page 27:

"The data is maintained [retained] by back up power if the key knob [ignition] is turned off."

And like Tomp just said...

" Push the upper button for 2 seconds while the average mileage is displayed, and the average mileage
resets to “– –. –”

Plus

"After resetting the average mileage, the numerical value is not displayed [computed] until 5 mL (0.2 US oz.) of fuel has been used and 100 m (328 ft) has been traveled."

[clogan]

FWIW, I used to reset my average at every fill up, and then compare the display average to actual (distance ridden/gallons to fill) mpg at every fuel stop. I found significant discrepancies, and consequently have stopped concerning myself with it. Riding is much more enjoyable now that I simply buy more fuel when the "range" gets low. I've got one of BDF's gizmos that maintains the range function, even below 50 miles, and I prefer it to the flashing OEM "Low Fuel" message.

It's also interesting that the dash reading for "average" mpg on my Ford Focus similarly varies widely from computed actual mpg. Likewise, I have learned to ignore it. Privately, I suspect the internally computed mpg has something to do with fuel pulses thru the injector system, and that perhaps these pulses are affected by the varying ethanol content, or lack thereof, of the current fuel supply.

Or maybe not.

[lather]

Answering my own question from the manual, page 27:

"The data is maintained [retained] by back up power if the key knob [ignition] is turned off."

And like Tomp just said...

" Push the upper button for 2 seconds while the average mileage is displayed, and the average mileage
resets to “– –. –”

Plus

"After resetting the average mileage, the numerical value is not displayed [computed] until 5 mL (0.2 US oz.) of fuel has been used and 100 m (328 ft) has been traveled."

That statement suggests to me that average is computed  as mL of fuel injected per 100 meters traveled. And then converted to miles per gallon or kilometers per liter for display. That would account for the large fluctuations. I think

[B.D.F.]

I do not know what the algorithm looks like but the avg. mileage is a cumulative average of the instantaneous mileage since the last avg. mileage reset. It is not weighted in any way that I can see. And yep, the average mileage coupled with how much fuel is in the tank is what is used for the range calculation.

Mine is w/in about 5% or so of actual mileage. But I am using a Power Commander which skews the data because it changes the amount of fuel injected without the ECU "knowing" that it has been changed so some inaccuracy is to be expected. Back when the was stock (oh those first few days....  ) I found the mileage indicator extremely accurate, which makes perfect sense because the ECU has extremely accurate date on just how much fuel was injected on every single injection cycle of the engine. I am actually surprised when people report that their mileage indicator is NOT accurate, at least on a stock bike.

Brian

Can anyone tell me the algorithm used to calculate average mileage and range (I presume the latter is based on the former) on the C14 display? I assume the average mileage is based on a rolling average of the current mileage, but I would like to know the span that is measured (i.e., average of current mileage over previous 1 mile, average of current mileage over previous 50 miles, or ?) and whether it's weighted (i.e., more emphasis on later miles in the range, etc.). Anyone know?

While we're at it, is there any way to occasionally reset the average mileage calculation so that it forgets history and starts with a clean slate?

Thanks for the help.

[Rhino]

Really? Seems like it looks at the instant mileage updating every few seconds or so. I can slow down and within a few seconds see my range go up. Twist the grip and the range goes down.

I do not know what the algorithm looks like but the avg. mileage is a cumulative average of the instantaneous mileage since the last avg. mileage reset. It is not weighted in any way that I can see. And yep, the average mileage coupled with how much fuel is in the tank is what is used for the range calculation.

Mine is w/in about 5% or so of actual mileage. But I am using a Power Commander which skews the data because it changes the amount of fuel injected without the ECU "knowing" that it has been changed so some inaccuracy is to be expected. Back when the was stock (oh those first few days....  ) I found the mileage indicator extremely accurate, which makes perfect sense because the ECU has extremely accurate date on just how much fuel was injected on every single injection cycle of the engine. I am actually surprised when people report that their mileage indicator is NOT accurate, at least on a stock bike.

Brian

[B.D.F.]

Instantaneous mileage does update every few seconds. So does average mileage but the change in avg. mileage could be large or small with a large change in instantaneous mileage. It depends on how far into the average miles used to calculate the bike is; near the beginning, instantaneous mileage will have a large effect on avg. mileage. Near the end of the trip, it will have a very small effect on avg. mileage.

The range indicator always uses instantaneous mileage by the way.

The way averages are calculated is very simple: just as an example, suppose the avg. is calculated every 10 miles....

@ 10 miles, the average is 40 MPG
@ 20 miles, the MPG of the last 10 miles is added to the first 10 miles and the sum divided by two.
@30 miles, the MPG of the last 10 miles is added to the first 20 miles and the sum divided by three.

..... and so forth

@240 miles, the last 10 miles is added to the previous 230 miles, and the sum divided by 24. So a big change in fuel economy (mileage) near the end of the tank has very little impact to the average.

It will get even worse if the average mileage reading is not zeroed out at each fill- up and is allowed to run for more than a tank of fuel. For example, if you had an average MPG reading over 1,000 miles and suddenly doubled you mileage for the next 10 miles, it won't make much difference in the average reading. But having an average for 10 miles and then doubling the mileage for the next 10 miles will change the average reading by 50%, which is a huge amount.

Brian

Really? Seems like it looks at the instant mileage updating every few seconds or so. I can slow down and within a few seconds see my range go up. Twist the grip and the range goes down.

[phildobaggins]

Racing around or even harshly commuting (tm) I barely get 27mpg but my connie will display a proud 37-40mpg average somehow.

[maxtog]

This is giving me a headache now!

Let's just ride

[clogan]

This is giving me a headache now!

Let's just ride :)

That works for me!    :thumbs:

[B.D.F.]

When did you last reset the avg. mileage readout?

Brian

Racing around or even harshly commuting (tm) I barely get 27mpg but my connie will display a proud 37-40mpg average somehow.

[tomp]

+1 on that.  The longer you leave the average mpg setting untouched the more unreliable it becomes.  If one rides the snot out of the 14, all the time the average should match your mileage calculations at 27-30 mpg. 

Had several bikes with the "avg mpg" read out, and if reset at each fill up, they have all been  rather accurate.  My last fill up avg on my 14 was 41.6 mpg, and my fill up to mileage calculations had me at 41/42 mpg.  Pretty close to the computer.

[Rhino]

Just did a ~1600 mile trip and reset the average mileage at the beginning. This was mostly easy cruising except some 80+ speeds crossing west Texas and I averaged 45.7 for the whole trip. Just doing quick calculations at each gas stop seems to confirm it to be right on the money. BTW: I had it in economy mode most of the time.