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Discussion Starter #1
This thread got me thinking about the trip computer on my ST3.

Since I got the bike, I'd just assumed that it's wild inaccuracy was due to poor design, but I never really asked anyone else about theirs. I did a quick search here and didn't come up with much, so now I ask... does yours work as expected?

My trip computer is inaccurate in every respect.

  • It's grossly non-linear
  • It consistently tells me that I average 55-59MPG, when measured MPG is 40-44. It once reported average MPG of 165 over about a hundred mile stretch.
  • It has insane estimates for estimated distance and estimate fuel remaining; it's not uncommon to see it report 300+ miles estimated to empty. This despite the fact that the bike could never go 300 miles on a tank ever.
I can't even remember all the silliness it's told me. But the thing I'm wondering is is it the same for everyone else?
 

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Retired Pipe Polisher C2H6O+
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I would have to say mine isn't exactly perfect. It usually shows about 2-3mpg less that what I actually get. It seems it got a bit worse when I switched to the DP EUC. But I'd say yours has severe dain bramage :)
 

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Life is too short to worry !
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The problem with the electronic trips is that they are measuring the con-sumption at a specific moment n time and if you are gently cruising on a light throttle it will base its calculation for mpg on that figure and then use it to calculate an estimated remaing range which not allow for the change in throttle usage so its not really giving you an average but a stap-shot in time (my old car fuel computer would regularly give 125+ mpg but the average would be vastly different in reality)
Also dont forget the difference in European/USA gallons - not sure if the trips are designed to read differently ?)
My analogue speedo is 10% optimistic but the trip is only about 2% out , nevr been clear how that happens but just get used to it.
 

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I can't even remember all the silliness it's told me. But the thing I'm wondering is is it the same for everyone else?
The only thing I believe is the odometer function. The clock doesn't even keep accurate time, it looses five minutes a week.
 

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My trip computer results are as bad as yours are. In fact, even the odometer is off. During a cross-country trip last year when I had the GPS on the whole time, I discovered that the bike's odo was reading around 10% fewer miles than on the GPS. What is funny is that makes my hand-calculated mpg better (when using the miles from the GPS) than using the miles from the odo, but not nearly as good as the mpg calculated by the trip computer. While I thought the trip computer would be a nice feature because I take the Duc cross-country every year, it's turned out to be totally useless.
 

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Discussion Starter #6
hmm... seems like a mixed bag, but I'm not alone here. Thanks for the info.

I haven't watched the odo very closely, but I think it's pretty close to accurate. I ride to work quite a bit, and I have some notion that the odo pretty well matches the what google maps claims is the distance.

My clock isn't very accurate either. Didn't even think about that til you mentioned it motersikelist. :)
 

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Discussion Starter #7
The problem with the electronic trips is that they are measuring the con-sumption at a specific moment n time and if you are gently cruising on a light throttle it will base its calculation for mpg on that figure and then use it to calculate an estimated remaing range which not allow for the change in throttle usage so its not really giving you an average but a stap-shot in time (my old car fuel computer would regularly give 125+ mpg but the average would be vastly different in reality)
Yeah, I do understand that. I haven't had one this wildly inaccurate before. Also, my last couple of cars have been spot-on in this regard. So I suppose I'm spoiled a bit. Also, the engineers could design a little common sense logic into the trip computer. Like maybe setting a max bound of 99.0 MPG, or a max tank range of 300mi, and not show that if the tank is only half full. :)


Also dont forget the difference in European/USA gallons - not sure if the trips are designed to read differently ?)
You mean imperial gallons? Hmm... I never really thought of that, and never read the book close enough. Is the system spec'd on imperial gallons? That would explain the discrepancy between what I read and what I measure.

Assuming my math is rightSay for example:
180mi / 4 US gallons (pumped) = 45 MPG equates to:
180mi / 3.33 Imp gallons = 54 MPG

The only glitch in this thinking is that if the spec's are imperial gallons, it would mean that the 5.5gal tank is about 6.5 US gallons, and that doesn't sound quite right.

Or are you saying that the tripmeter might compute in imperial gallons and the tank might be spec'd (or more likely converted from liters) in US gallons? That'd be kinda funny. Wouldn't explain some of the comical readouts I get for MPG and range, but still, that's pretty close to comedy gold. :D
 

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Discussion Starter #8
Yeah, I do understand that. I haven't had one this wildly inaccurate before.
In fairness to the Duc, I should mention that a BMW R1200RT I rode sputtered nicely to a stop with nothing but vapors in the tank while the trip computer showed a full tank and an estimated 390 miles range to go.
 

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"Or are you saying that the tripmeter might compute in imperial gallons and the tank might be spec'd (or more likely converted from liters) in US gallons? That'd be kinda funny. Wouldn't explain some of the comical readouts I get for MPG and range, but still, that's pretty close to comedy gold."

Sometimes life just gets too complicated LOL !
 

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me 3

Glad I found this thread. The data on my computer is pretty useless, and I was wondering if it was an issue with my bike, or a problem shared by others. Shared by others is good, because it means either 1) others have figured out how to fix it, or 2) we're all screwed, but at least we're in good company. Sounds like the latter is true in this case :)

I've been trying to do a little science and figure out what part of the data (if any) is useful. So far, my GPS and the odometer seem to be close enough to trust the odometer. The fuel data is all way off. I have a couple theories. If I come up with anything I can 'prove', I'll report back.

Regarding inaccuracy, as long as your gauge is always innacurate in the same way, you can at least use it to gauge things, at least relative to past performance. If your bike gets 250 miles on a fill, it doesn't matter much if you are 10% over or 10% under reality, as long as the amount of error doesn't change. You can get the same 250 every time, and use 247 as the mark to back off from WFO and start looking for a service station :D
 

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When you switch on the ignition the display tells you if it is set to EU (Europe - Liters), US (United States Gallons) or UK (United Kingdom - Imperial Gallons). The owners manual tells you how to change this.

Just a thought. Perhaps you are set wrong.

David
 
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