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Ultragauge fuel economy

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Old Dec 7, 2018 | 10:59 PM
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Default Ultragauge fuel economy

Since there have been a couple threads on Ultragauges so I figured I’d add mine.

I’ve got mine set up for 25.5 gallons but the fuel economy used to be around 1 mpg off but now it is WAY high and 2-4 mpg off when I fill the tank. Obviously the fuel left in the tank is off too.

I tried some time back to calibrate, but that didn’t work. Any ideas?
 
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Old Dec 8, 2018 | 09:57 AM
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I've got the tank at 24.6 gal. I just use the MPG on the ultra gauge as a measuring stick,
usually 1 MPG off on the low side. If you want accuracy you gotta do the actual math.
 
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Old Dec 8, 2018 | 10:45 AM
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Oh yeah, definitely know manual calculations are best. I just like to monkey with stuff and figure it out.

So I finally read the manual a bit more in detail and I might get it a bit closer. I changed the setting to force the fuel measurement to be from the MAF as opposed to Auto or MAP.

Everything I’ve read says the tank is 25.5 gallons. Are you just kind of making it up to try to account for inaccuracies in the fuel measurement?

This really is just a science experiment for fun. I get the temp, and that’s all that really matters.
 
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Old Dec 8, 2018 | 12:15 PM
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Are you running stock sized tires or oversized tires? This will factor into your calculation.
 
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Old Dec 8, 2018 | 01:18 PM
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265/60/18. The speedo is spot on despite those being a scoshe larger than stock, so I don’t think that should be causing any issues per se.
 
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Old Dec 8, 2018 | 01:23 PM
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I have stock tires and my odometer is off like 5mph at highway speed.

Kind of annoying.
 
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Old Dec 9, 2018 | 08:05 AM
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Originally Posted by longtallsally
Oh yeah, definitely know manual calculations are best. I just like to monkey with stuff and figure it out.

So I finally read the manual a bit more in detail and I might get it a bit closer. I changed the setting to force the fuel measurement to be from the MAF as opposed to Auto or MAP.

Everything I’ve read says the tank is 25.5 gallons. Are you just kind of making it up to try to account for inaccuracies in the fuel measurement?

This really is just a science experiment for fun. I get the temp, and that’s all that really matters.
Everything on Google says 24.6
MPG: 13 city / 17 highway
Engine: 4.0 L V8
Towing capacity: 7,700 lbs
Curb weight: 4,576 lbs
Fuel tank capacity: 24.6 gal
Payload: 1,487 lbs
 
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Old Dec 9, 2018 | 11:05 AM
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Since you like science experiments... Just because your UG matches your speedometer doesn't mean they are accurate. Thanks to modern technology you can use an app or a GPS device to determine your actual speed.

Go out on a long lonely stretch of highway and see if all three are the same. Chances are they won't be. While you are at it, use the stopwatch to determine if all three are accurate. One mile at 60mph should take one minute exactly.

Personally my UG is 5mph off the speedo and the speedo is off of reality if you can trust an MPH app to be accurate. Once you conclude that your MPH is or is not accurate then you can know whether your odometer is accurate. The two are inherently related. If the odometer is not accurate then you are introducing a false number into your MPG calculation. Usually that number is not in your favor. Thus the only true way to know your mpg is by filling your tank and marking a waypoint in a known accurate map application, then driving say 100 miles to a new gas station and filling up. Note if the odometer miles is different than the map app distance... Then do the math the old fashioned way with the most accurate data.
 
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Old Dec 9, 2018 | 11:19 AM
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Originally Posted by Rosslato
Everything on Google says 24.6
MPG: 13 city / 17 highway
Engine: 4.0 L V8
Towing capacity: 7,700 lbs
Curb weight: 4,576 lbs
Fuel tank capacity: 24.6 gal
Payload: 1,487 lbs
Dunno, I trust the RAVE a good bit more that guggle.

 
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Old Dec 9, 2018 | 11:27 AM
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Originally Posted by Dave03S
Since you like science experiments... Just because your UG matches your speedometer doesn't mean they are accurate. Thanks to modern technology you can use an app or a GPS device to determine your actual speed.

Go out on a long lonely stretch of highway and see if all three are the same. Chances are they won't be. While you are at it, use the stopwatch to determine if all three are accurate. One mile at 60mph should take one minute exactly.

Personally my UG is 5mph off the speedo and the speedo is off of reality if you can trust an MPH app to be accurate. Once you conclude that your MPH is or is not accurate then you can know whether your odometer is accurate. The two are inherently related. If the odometer is not accurate then you are introducing a false number into your MPG calculation. Usually that number is not in your favor. Thus the only true way to know your mpg is by filling your tank and marking a waypoint in a known accurate map application, then driving say 100 miles to a new gas station and filling up. Note if the odometer miles is different than the map app distance... Then do the math the old fashioned way with the most accurate data.
Ooh, some good experiments here. I know the speedo (in the vehicle) is accurate per GPS and radar (driving by those radar things to make sure you are going the accurate speed in neighborhoods and on the freeway). Having a healthy career in telematics has me not trusting GPS, but it is another data point. I’ll have to check the trip distance as well- easily done for the morning commute.

Anyway, I agree that I should verify the speed in the UG to the vehicle speedo. I’ll have to see if there is a way to correct the speedo in the UG to mirror that of what is displayed as that is a good example.

Good input and thanks- I hadn’t thought of some of those variables.
 
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