Gas gauge
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Joined: Nov 2009
Posts: 92
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From: Chesapeake VA
Gas gauge
I live in VA & i noticed that whenever I get gas in NY or NJ the gas gauge reads 450-500 miles till empty. But when I get gas in VA the gauge reads 340-345 miles till empty. Anyone know why this is?
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Joined: Sep 2000
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From: Far NW 'burbs of Chicago
St. Jude Donor '13
Probably related to the MPG you were getting before the fillup.
AFAIK,
The car doesn't know anything about the quality of the gas you just purchased (unless you get into knock retard) and it doesn't know anything about the roads you will be traveling in the future. So it just extrapolates from what you have been doing in the recent past.
AFAIK,
The car doesn't know anything about the quality of the gas you just purchased (unless you get into knock retard) and it doesn't know anything about the roads you will be traveling in the future. So it just extrapolates from what you have been doing in the recent past.
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Advanced
Joined: Nov 2009
Posts: 92
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From: Chesapeake VA
That can't be the case bc like I said. Whenever I get gas in VA the gauge reads 340miles till empty. But like I said in NY,NJ it always reads 400 plus. It has to be a logical explanation for this.
Team Owner
Joined: Sep 2000
Posts: 25,001
Likes: 2,701
From: Far NW 'burbs of Chicago
St. Jude Donor '13
The Range calculation algorithm is a mystery, at least to me. It seems to use your recent mpg but with something of a blending. For example, if we get stuck in traffic and sit there with the engine running, the range won't change immediately. But after a few minutes the range will start to decrease.
Also, if we have been in town before buying gas, our range will show a fairly low number after we fill up. But when we then get out on the highway and start getting better mpg, the range will actually start to increase after a few minutes as the car recognizes the better mpg we are getting, even though it has burned some of the fuel on board.
My guess is still that your car is seeing something in your recent mpg before buying gas, that causes it to predict a higher or lower range. Going from 18.9 mpg to 22.9 mpg will give the range variation you describe, and that much mpg difference happens easily.
I have NOT found that re-setting the average mpg in the DIC has any effect on the predicted range, that seems to be a separate calculation.
Hopefully, someone will come along that has the mathamatical answer.
Also, if we have been in town before buying gas, our range will show a fairly low number after we fill up. But when we then get out on the highway and start getting better mpg, the range will actually start to increase after a few minutes as the car recognizes the better mpg we are getting, even though it has burned some of the fuel on board.
My guess is still that your car is seeing something in your recent mpg before buying gas, that causes it to predict a higher or lower range. Going from 18.9 mpg to 22.9 mpg will give the range variation you describe, and that much mpg difference happens easily.
I have NOT found that re-setting the average mpg in the DIC has any effect on the predicted range, that seems to be a separate calculation.
Hopefully, someone will come along that has the mathamatical answer.
Last edited by Gearhead Jim; Apr 18, 2013 at 07:41 PM.
