Mileage- computer vs calculated differences
Senior User
Joined: Jun 2005
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OK, I had one other thought. My truck was built in late 2002. This was prior to ethanol addition to gasoline (if my memory serves me), prior was MTBE. Ethanol is a lower energy value to gasoline compared to MTBE. Could this throw off the computer since it was based opn a different fuel blend with more energy content per gallon?
Postmaster
Joined: Oct 2006
Posts: 4,171
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From: SE Texas
OK, I had one other thought. My truck was built in late 2002. This was prior to ethanol addition to gasoline (if my memory serves me), prior was MTBE. Ethanol is a lower energy value to gasoline compared to MTBE. Could this throw off the computer since it was based opn a different fuel blend with more energy content per gallon?
JL
Postmaster
Joined: Oct 2006
Posts: 4,171
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From: SE Texas
does that mean the sct tuner man can make an adjustment to the tune to correct the readout? i am putting a used engine in this in a few weeks. once it's in, i am gonna run up to the tuner and have him make sure everything in the tune is still all set.
edit: i assume if i got something like a scangauge ii, it would be just as inaccurate as it gets it's info from the obdii port?
edit: i assume if i got something like a scangauge ii, it would be just as inaccurate as it gets it's info from the obdii port?
JL
Elder User
Joined: Jun 2006
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From: Lunenburg, MA
what parameters would i ask him to look for? i've seen the tuning screen....there are like a million changes that can be made.
Logistics Pro
Joined: Jan 2001
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From: Central NYS
Now if your injectors are slowly becoming plugged up and not spraying fuel at their rated amount the PCM will increase the injector on time (and up the long-term-fuel-trim) to keep the HO2S happy. In that case the read out would show less mpg than you are actually getting.
And when you manually calculate your fuel mileage to check the accuracy of the overhead readout, take a look at the location of the fuel take fill pipe. It is way at the end of the tank, and IIRC, it does not enter the tank at the highest point. It is almost impossible to fill the tank twice in a row to the exact same level to determine how much fuel you used. Your lucky to get within a gallon or two.
Junior User
Joined: Oct 2007
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I think that the Miles to Empty screen is based on previous driving habits, not current. There will be times when I'm driving all highway (long road trips) and the Miles to Empty will read ~385 at full when I start off. When it reaches 50 miles and I go to refuel, it'll take only about 20 gallons to fill up the 28 gallon tank (so no way I only had 50 miles left), and then the new full reading will say 450 miles to empty. I'll then drive a highway / city mix on that tank, get down to 50 miles, and it'll take 25 gallons to fill up the 28 gallon tank.
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Freshman User
Joined: Apr 2010
Posts: 32
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From: Space Coast, FL
Well, I had been resetting the tripmeter every time i filed up and still got the high reading, so I tried disconnecting the negative battery terminal and reconnected about 30 minutes later. now I'm getting readings of 16.4 mpg which is about what I calculated (miles/gallons on fill-up).
I did not notice any change in performance.
I did not notice any change in performance.
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wagoncrazy
6.0L Power Stroke Diesel
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Sep 10, 2008 06:11 PM
