on board computer

[dmr]

This may seem strange, but I was sitting at a light and started thinking about my on board computer and the information that shows how far I could go on the remaining fuel. It struck me odd that it showed I had 86 more miles, despite sitting motionless. Theoretically, if I did not move, I would run out of gas on that spot. Just how does this computer figure mileage remaining? It doesn't seem to use the speedometer, and if it uses engine rpm does it also include the selected gear? Just wondering.

[TomfromMD]

IIRC, the recorded fuel mileage (since last reset) and fuel remaining are used to compute miles to empty. The current speed (or lack of it) is essentially irrelevant, except that sitting at the light long enough will lower the computed fuel mileage.

[Grey_Matter]

I think it is done with magic. Kind of like checking the oil level on my 1150 GSA.

[The_Veg]

DMR, dude, you're thinking too much about it.

[dmr]

Yeah, I know. I'm going to experiment at the next refuel. It was a really long light.

[HFD190]

If it makes you feel better, I was riding with a guy last fall that ran out of gas while he was waiting at a red light...

[dmr]

Can't say I've ever heard or done that. (Did he look at how far the computer said he could go?)

[mjuskiw]

Geez I kinda have the same head. I keep it quiet with an Ipod
A little background music and the beasts stay at bay and I just enjoy the ride.

Getting the most miles from a tank is like figuring out how many licks to the center of a Tootsie pop. I wasnt blessed with the patience for either. When my low fuel pops on I usually downshift, "56 miles ? -I can burn this in 20" . Someday ill have a few relaxing miles pushing the bike to figure it all out.

If I understand the earlier post its actually looking at my average fuel consumption since it was reset. So it is seeing the morning I was late for work and the Sunday when I was in no hurry at all.

My question at this point is what is a reset. If I disconnect the battery and have to reset the clock is it starting over or is this something that would happen at service ect. Just how much does the computer remember ?

MJJ

[pbbeck]

I believe the computer calculates distance to empty using the average of several periodic measurements including fuel consumed, distance traveled, and remaining fuel.

I think the fuel gauge also shows the average fuel level over several measurements, which explains why it takes a while to register full after refueling.

[dmr]

ok, round two...
Filled the tank last night, waited until the fuel level went to full, and reset both the average speed indicator and average mpg. Both stayed at ----, which is what I would expect. But the distance to travel read 225 miles. (12RT) I sat there for a minute or so, but nothing changed. I rode 50 yards to a light. The average mpg went down to 15, the average speed went to 7, but the remaining miles remained at 225.

Once I got moving, the remaining miles consistently increased until I got home. I think it ended around 250 or so. The trip odo was at 218 when I refueled.

Enough. I think I will get an IPOD.

[TomfromMD]

It seems like the OBC is using the last MPG calculation (before you reset it) & multiplying by the tank capacity to get the miles to empty figure, at least this is how it acts on both my BMW car & bike. After a fill, I generally get a read out of aroung 350 miles, with the mpg reading 50, but that assumes a 7 gallon tank. By nursing the last few drops in & filling it 1/2 way up the neck, I can get in 5 gallons with the reserve light (1.1 gal.) having just come on. So as MCN said in their test, the tank apparently holds only a bit over 6 gals.

It's also entertaining to watch the miles til empty plummet as you near reserve. I've had it go from 80 to 50 in about 5 miles (the BMW cars are the same).