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1998 DeVille / 173,000 miles
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121 Posts
I don't know about non ethanal vs ethanol gas milage. But my 98's fuel mileage computer is very accurate, with the stock size tires. I think if you change the overall diameter of the tire, the readings might change. If you want to know exactly how different tire size affects your speedometer, go to the tire info section on Discount Tire's website. By knowing that, you can also figure out a change in fuel mileage.
 

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White Diamond '03 DHS (with DTS floor shift)
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87,115 Posts
The gauge is pretty accurate and yes non ethanol fuel will deliver slightly better mileage.
 

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1998 Deville
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369 Posts
Discussion Starter #4
I just read this on another website I found on Google. #36 .I started noticing a drop in gas mileage the first of the year. I keep track of fill ups and mileage for business purposes. I was averaging 20 mpg prior to January. I am now averaging 15 mpg or a 25% loss. I contacted the local gas providers in the area and they confirmed they changed to an E10 formula in January. Prior to calling, not knowing what was going on, I asked about ten friends if they noticed a drop in mpg and they all confirmed they have. None of us knew what was happening. I started doing everything suggested to increase gas mileage - ie. tire pressure, etc without any change. At first I was thinking I was having engine problems of some sort. So now we are paying the same price at the pump but getting less miles for the product, while corn prices rise as well. I asked the provider if they had any suggestions and they suggested changing the fuel filter as the ethanol probably cleaned out the fuel system and gunked up the filter. My problem is that my fuel filter is attached to the fuel pump inside the gas tank, which means if it is gunked up and is causing problems, the E10 has just caused me another expensive headache. I asked if the pumps are marked indicating the blend is E10. I was told there is a small sticker that says it “may” contain up to 10% ethanol. I have yet to notice it. So, what do we do now?

Comment by Darrell in Pennsylvania — Apr 10th 2008 @ 12:16
 

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1990 350 Brougham (The cruiser), 1988 Mark VII LSC (The DD)
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5,545 Posts
The gauge in my '88 is accurate to about .1 mpg when I use midgrade or premium. If I use regular it is off by about .5 mpg.

Some cars do very well with non-ethanol gas and some cars make no difference. We put non-ethanol gas into my Dad's '94 Ford E-150 and got almost 120 more highway miles per tank than we did on ethanol gas. My grandmother's Crown Victoria also does about 100 more miles per tank. However, when we put non-ethanol gas into my Mom's '00 Blazer it made no difference at all.
 

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White Diamond '03 DHS (with DTS floor shift)
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87,115 Posts
Alcohol has about half the BTU's of gasoline thus will produce about 50% less mileage. Do the math on 10% ethanol and you'll be pretty close.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,497 Posts
Instant fuel use hops all over the place and is fun to watch but useless for gas mileage calculations.

Long term average is dead nuts over long periods, and the shorter the time between resets, the less accurate it is: Say you fill up and reset the long term average. You get on the ramp and accelerate to 60 mph and drive for a half hour at 25 mpg. You get off the highway and get stuck in traffic for a half hour, which = 0 mpg. What's your average for the hour ? 12.5 mpg. You'll see the numbers climb up and down quickly over the first couple of tanks, then, as more and more miles accumulate, the long term average evens out.

If you want accurate fuel mileage over a particular tank full, go back to the best method.....miles driven divided by fuel used. (and the fuel used function in the DIC is very accurate also.)
 

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01 frontier , 89 Shelby CSX vnt
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14,607 Posts
I reset avg mileage whenever i change my driving , say a highway run , or if i make a change to the car

i like instant because it can help me trim the car out on the highway ...ie give it a little gas after resumeing the cruise controll so it doesnt slowly accelerate and keep the torque converter unlocked ...ive gotten 28 mpg on a tank of fuel , the computer and my math were within .2...lately i get around 12 becuse i dont go far , to the store and back or taking my grandmother places in town
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
You mean NON-ethanol fuel is still available in some states? Here in Hawaii, only aircraft are allowed to burn it. Ethanol is mandatory here for us little people who drive cars. My Lincoln suffered terribly mileagewise when that law went into effect.
 

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1998 Seville STS / 2013 Chevrolet Impala
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1,889 Posts
^Almost all fuel in IL is at least 10% ethanol.


To the OP: I wouldn't use all E85 in these cars. They'll run on it fine, but ethanol likes to eat all the little rubber pieces (seals and such) in the fuel system. It's better to dilute the E85 with gasoline.
 

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1999 White Diamond ETC
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2,538 Posts
The reason it is so accurate is that each fuel injector is rated to a specific amount of fuel deliver per pulse. The computer is calibrated to the numbers specific to the factory fuel injectors (this is all electronic and computer controlled). So if you change to a different type of fuel injector, then it will be off. Likewise if one of the fuel injectors leaks, it will be off.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
The reason it is so accurate is that each fuel injector is rated to a specific amount of fuel deliver per pulse. The computer is calibrated to the numbers specific to the factory fuel injectors (this is all electronic and computer controlled). So if you change to a different type of fuel injector, then it will be off. Likewise if one of the fuel injectors leaks, it will be off.
so it's not even really based on the actual gasoline consumption? that's not fair. No wonder when I had 2 leaking injectors the car was saying the mpg was okay, but I kept wondering where all the fuel was going. Finally, I did the math and figured it out. That big trail of white smoke that everyone said was coolant due to the blown HG was really misted gasoline due to the leaking FI's.
 

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White Diamond '03 DHS (with DTS floor shift)
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87,115 Posts
Right, the computer counts injector pulses and pulse widths and does the math. It's accurate if everthing is in good order. A leaky FPR will not be calulated for example.

If you had a trail of white "smoke" (unburned fuel vapor), you where very very rich. If you'd have held a match to the pipe, you'd have had a flame thrower. Should have riged a spark plug to the pipe with a toggle switch to turn it on and off. It would have been quit a show at night.
 

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1990 350 Brougham (The cruiser), 1988 Mark VII LSC (The DD)
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5,545 Posts
^Almost all fuel in IL is at least 10% ethanol.
Casey's is the only place I know of in IL that has non-ethanol gas, and it costs 10 cents more per gallon than gas with ethanol added. However, Iowa is a different story. When I went there last year they have no 87 octane. The have 89 with ethanol, 89 w/o ethanol and then 93. The first two were the same price and the premium was 10 cents more per gallon.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
If you had a trail of white "smoke" (unburned fuel vapor), you where very very rich. If you'd have held a match to the pipe, you'd have had a flame thrower. Should have riged a spark plug to the pipe with a toggle switch to turn it on and off. It would have been quit a show at night.
LOL! I might also have broken CHA-CHA's record! :burn:
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The percentage of Ethanol in any grade of gasoline in any state or county is set by that state's emissions laws.

Most vehicles will operate satisfactorily on E-10, and only a tiny percentage have been built to operate on E-85. The required fuel/air ratios for E-85 are very different from E-10 or pure gasoline.

If your state has an Ethanol percentage legally specified for emissions, then all grades of gas must then carry that Ethanol load, but it will never exceed 10% for emissions control. Some states also pump E-85, but that blend is not mandated by the EPA.

To find out what your state and county are required to pump by EPA law, go to www.epa.gov/otaq/rfg/whereyoulive.htm . That's the horse's mouth - anything else is pure speculation.

The above does not prevent any fuel supplier from pumping anything up to E-10 in a non-emissions state. Don't forget that the only reason we're burning Ethanol is the Corn Lobby - and if you live in a corn state, it's a safe bet that you're burning Ethanol, law or not.
 
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