Incorrect instant fuel and average fuel reading

[Perch85]

Hi everyone,

I have a 2016 MT07. Lately it’s been showing the instant fuel usage at 40l per 100km when normal riding. If I open it up it drops to 7L per 100km. 
with this the average fuel

gauge sits at 0.01L per hundred.

looking at an upgrade soon so it would be good to get to the bottom of it.

Anyone have an idea of what’s going on? 
 

Cheers 

[Triple Jim]

You're saying that when cruising, your fuel display says you're using 40 liters per 100 km  (5.9 mpg) and when you open the throttle is says 7 liters/100 km (33.6 mpg)?

And are you saying that the instantaneous fuel usage follows (is the same as) the average fuel usage?

Edited November 13, 2022 by Triple Jim

[Perch85]

The instantaneous fuel while cruising is high when coasting around town. It drops once the throttle is opened.

the average fuel always read 0.01 now no matter how far I ride, even after a rest 

 

hope that helps? 
just been on a long haul of night shifts so the brain is a bit scrambled 

[Perch85]

The actual amount of fuel being used isn’t as high as the reading for instantaneous 

[klx678]

I'm not overly impressed with the instant fuel use reads.  It jumps around so much and isn't much use.   My HR-V will go from below 20 mpg to 90 mpg (max reading) and everywhere in between when driving normal cruising.  All it takes is a small grade up or down to make radical differences.   I just look at the average mpg - we are around 29 mpg, all kinds of driving included.   I haven't looked at the instant readings on the HR-V maybe twice and for no more than 15 seconds, much less look at the reading with the XSR700.  

 

With the XSR actually I rely on one of the trip meters (whichever one I set to zero) and whatever miles I know I can run on a gallon, plus the "tea cup" for a general guesstimate.  When the "tea cup" flashes I've still got around a gallon left in the tank, but i also plan a gas stop at the next chance.   I've never been too enthusiastic about pushing a bike that has run out of gas, so I'd rather be conservative on how far I'll go when the "tea cup" is empty and flashing.

Edited November 13, 2022 by klx678

[shinyribs]

I don't know for certain, but I believe the instant fuel mileage is calculated in the ECU based of throttle position and rpm. You can calculate how much fuel an injector flows, how long the injector is being told to fire, and how many times per second based on rpm. If you realistically average 50mpg then you can theoretically expect to see everywhere from 0mpg to 100mpg on the instantaneous reading.  The ECU doesn't, however, have a way to accurately measure load on the engine. How many riders of what size, how much luggage, how steep of a grade. So the instant fuel usage display is somewhat useless though it's likely to be showing a fairly accurate number. 

With a throttle lock on a flat highway the instant fuel mileage will settle on to a consistent number, but even the slightest turn of the throttle will throw the number way off.