Indicated vrs Actual Milage_update
#11
Re: Indicated vrs Actual Milage_update
Originally Posted by AKM
I drive 80MPH or more on the freeway for 17 miles and pull a 35degree grade at about 60MPH for over a mile and a half as my regular 5 day commute.
Where are you driving to be climbing a 35 degree grade that is a mile and a half long? Are you sure it is that steep? Is this a public road?
#12
Re: Indicated vrs Actual Milage_update
Originally Posted by WVGasGuy
[I]My bet is the most cause is variable filling level.[I]
95% of my fills are at the same station. I always fill on flat, level surface. I slow the pump as it gets close to full and let it kick off. I give it two squeezes that kick off (that usually adds avout 2/10ths of a gallon. I don't "overfill" but I try to fill it to the same level as possible by using a consistant fill procedure.
Also my actual gallons used compared to my theoritical gallons used is over 5 gallons and that would be a consistant 0.2 gallons error per refil. I don't think I could be off that much consistantly each time. Occosionally yes, but not consistantly, and if so it should average out.
95% of my fills are at the same station. I always fill on flat, level surface. I slow the pump as it gets close to full and let it kick off. I give it two squeezes that kick off (that usually adds avout 2/10ths of a gallon. I don't "overfill" but I try to fill it to the same level as possible by using a consistant fill procedure.
Also my actual gallons used compared to my theoritical gallons used is over 5 gallons and that would be a consistant 0.2 gallons error per refil. I don't think I could be off that much consistantly each time. Occosionally yes, but not consistantly, and if so it should average out.
#13
Re: Indicated vrs Actual Milage_update
Originally Posted by spiff72
Where are you driving to be climbing a 35 degree grade that is a mile and a half long? Are you sure it is that steep? Is this a public road?
It's a nice four lane public road and one of the few places left where you can still drive fast and fairly safe (going upward anyways).
Parts of California have very hilly (and beautiful) areas.
#15
Re: Indicated vrs Actual Milage_update
Originally Posted by ken1784
Anyway, the computer number is very stable, but it has some steady error about 2% on Prius case.
Ken@Japan
Ken@Japan
Another thing that could affect the actual vs MFD lifetime: I replaced the Goodyear Integrities (855 Revs/mile) with Goodyear TripleTreds (863 revs/mile) after about 4 months. I THINK that would affect the MFD calculation toward a very slightly higher MPG value since it 'thinks' I went slightly farther than I really did. When you are getting 500 miles on a tank, those extra 7 revs/mile do add up. Of course, that should also affect the odometer so maybe the 'actual' calc is equally affected? So maybe it really just explains why I get a little more gas in when I fill compared to the number of gallons I have presumably used based on the # of miles and the MFD average.
#16
Re: Indicated vrs Actual Milage_update
I've been filling up at different stations. When the pump stops, I stop pumping. I have found that with the exception of my first fill-up the Camry's reading has been 0.8 to 1.0 mpg higher than my calculated average.
When you manually measure your mileage you're working with large numbers (500 - 650 miles & 13 - 16 gallons). An error of a few ounces, which would be a high error for a gas pump, would not make a large difference in your calculated mpg. When sensors in the car are measuring your gas usage they're working with extremely small amounts of fuel. The sensors have to convert the fuel usage into digital readings. Errors due to rounding in the least significant bits (LSBs), although small, could probably cumulatively add up to a larger error.
The only flaw to this logic is that rounding errors should offset; some should be low and some should be high. Theoretically it should round to zero. However, most people seem to be reporting higher mpg on the Camry display than calculated. That I can't explain.
Originally Posted by WVGasGuy
The computer is calculating dynamicly
Yeah, I don't get the point (Toyota's). If they have an accurate measurement and the miles are saved electronically why can't the average be accurate? I don't want it assuming anything I just want it to tell me how I've done so far.
Yeah, I don't get the point (Toyota's). If they have an accurate measurement and the miles are saved electronically why can't the average be accurate? I don't want it assuming anything I just want it to tell me how I've done so far.
The only flaw to this logic is that rounding errors should offset; some should be low and some should be high. Theoretically it should round to zero. However, most people seem to be reporting higher mpg on the Camry display than calculated. That I can't explain.
#18
Guest
Posts: n/a
Re: Indicated vrs Actual Milage_update
What do think about re-calibrating the tires in the NAV system.... Will that help - maybe it was really never calibrated in the first place...
Is that possible? I wonder why they put 60 series tires on these in the first place. I wonder if the speedo was not calibrated for 215 / 65 series tires which would make it about right.
(I guess if we put 85 series truck tires on these we could increase our warranty coverage by a 1000 miles or so)
Is that possible? I wonder why they put 60 series tires on these in the first place. I wonder if the speedo was not calibrated for 215 / 65 series tires which would make it about right.
(I guess if we put 85 series truck tires on these we could increase our warranty coverage by a 1000 miles or so)
#19
Re: Indicated vrs Actual Milage_update
Originally Posted by RCFlyer
What do think about re-calibrating the tires in the NAV system.... Will that help - maybe it was really never calibrated in the first place...
The mileage or odometer value does not change.
Ken@Japan
Thread
Topic Starter
Forum
Replies
Last Post