Fooled by the MPG-ometer - Page 3 -
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post #31 of 39 Old 12-28-2013, 07:02 AM
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I'm not sure why everybody's is off. When I went to 35s I recalibrated my speedo to be accurate at 70mph. (Oddly that required setting Superchips to 33.75" tires, running 35X12.50 MTRS @ 30psi). Anyways my neck of the woods is flat as a pancake, and while I am not the Stig or a Grandma behind the wheel, my dash reads dead nuts compared to old school measuring.

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post #32 of 39 Old 12-30-2013, 11:49 AM Thread Starter
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I filled up a while ago, and the mpg-o-meter was almost right on. Maybe I got a bad batch of gas earlier.
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post #33 of 39 Old 12-30-2013, 03:02 PM
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Or you forgot you left it idling because it's colder than normal outside... If I can have pretty consistent highway mileage readings on trips using all sorts of gas in outdoor temperatures from around +90 to -40 (not counting humidex or windchill factors) it's doing a darn good job. Besides, as long as my distance to empty always underestimates range on me provided I keep similar driving pattern as last 100 miles or so, I am happy happy happy.
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post #34 of 39 Old 12-31-2013, 11:03 PM
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My 2014 is dead on with my trip to kc.

Thank you Jesus
2014 Wrangler Sport 1.5" spacers in front .75 rear, 1" BL 255/80/17 BFG KM2
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post #35 of 39 Old 01-01-2014, 06:09 PM
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Originally Posted by SubAtomicGenius View Post
Could be temperature changes, cold weather, blended fuel, etc. Accuracy is also highly dependent on the driver's driving habits.
nope, they just aren't accurate. had 4 jeeps with them in them 2 x liberties and 2 x wranglers the only time they come close is if you drive 50-60 all the time. I compute mileage the old fashioned way, paper and pencil.
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post #36 of 39 Old 01-19-2014, 05:33 PM
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Originally Posted by Dead-On View Post
I fully understand that but the calculations are affected by when I press the reset button. I have to be on relatively flat ground and accelerating at an average speed for it to be relatively correct. If I decide to hit the reset button and let off the gas for just 5 seconds to hit it the average will read high even if my trip is hundreds of miles. It seems to be worse if I hit the accelerator. If I am accelerating when I hit it (even for a few seconds) the average will read about 2-3 MPG lower than the actual usage even if I'm driving hundreds of miles. There's something up with the initial calculation process when you hit the reset button on my JKU .
I'm going to take a stab at this.

You're hitting the "reset" button. That'll reset your MPG to " -- " meaning nothing. It neither represents 0 nor does it represent infinity. So when you hit reset while barley pressing the gas pedal going downhill it'll show a high number. From the moment you hit reset to the moment you look at it, the number that shows is the Jeeps calculated average MPG for that time frame. You are probably achieving 40-60 MPG while going downhill. The same principle applies while accelerating uphill. You are actually achieving around 2-6 MPG.

If you let go of the gas pedal the MPG the computer plugs into the equation is --. So the computer is calculating -- for the distance you have your foot off the gas pedal. In theory you are achieving infinite miles per gallon while you are coasting in gear.

The calculation is a bit different while you coast in neutral. But I don't have specific figures of how much gas the engine uses to keep itself idling.
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post #37 of 39 Old 01-19-2014, 07:10 PM
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mine does the complete opposite. my 2013 with 33s says i get less than what im actually getting. told me i was gettin 16 but when i actually figured it up it was 17.3mpg
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post #38 of 39 Old 01-20-2014, 02:21 PM
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Hand calculated this morning @20.1 mpg. Lie-o-meter told me 20.3.
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post #39 of 39 Old 01-20-2014, 03:32 PM
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You must be stock with the 225 tires lol
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