Is there a way to calibrate the MPG meter in the message center? It seems that the meter is 1.5 MPG better than if you calulate it on calulater. Or better yet, which one is correct?

 

Well, unless your math is wrong or you don't fill up to the same point each time, the manual calculation method is more reliable and repeatable. There is a reason why the stock mpg meter is called the "Lie-O-Meter."

Or you can get a scangauge and be all set. I bought one becasue my cheap old 2004 XLT 6.0L didn't come with any fuel computer. It has to be the most used accessory I have bought for my truck.

 

when you say fill up to the same point , do you mean put the same amount of fuel in each time? Is there a topic that will tell me exactly how to calculate this?

 

I have to reset mine each time I fill up to any sort of accuracy. Also when I fuel up, I can usually go another 4 or 5 bucks of pumping after the first click on the pump. So maybe your not getting a completely full tank. Typically I'm getting 16-19 mpg or 11-13 mpg when hauling my travel trailer. It also has to run about 1/2 hour to an hour before it gets up to those numbers, since it's giving average mileage not actual mileage.

 

Basically gas mileage is miles per gallon(miles driven / gallons used). Most people calculate it per fill up. 40 gallons put in(dual tanks), last fillup at 70250 miles, this fillup was at 70690 miles for 440 miles traveled.(70690-70250=440) 440 miles / 40 gallons = 11mpg.('77 F150 with a 400cid engine)

You do several tanks and get numbers like(in my case) 10.5mpg, 11.1mpg, 10.0mpg, 11.7mpg. You can then average these numbers to get your "normal" gas mileage. (10.5+11.1+10.0+11.7)/4 = 10.825mpg (4 'cause there were 4 numbers)

Filling up at the same point is poorly worded. No offence meant. Filling up TO the same point is perhaps a better way to say it. If you drive 400 miles, half fill the tank, then calculate your mileage you'll get an outstanding number. Then on the next fillup you'll drive 200 miles, and have to completely fill the tank. And you'lll get a horrible number. Your mileage did not really change. The long term average will not change. You just got funny numbers because of the different way you put gas in. Most people, me included, just hate the random ups and downs. So you limit this by filling your truck the same way each time. You can stop the first time the gas pump clicks off, or the second, just as long as you use the same number each time. My '77 is picky about how level the ground is. If the ground slopes away from the pump it fills completely. If the ground slopes toward the pump it leaves a gallon or two of air in the second tank.

Calculating gas mileage on every tank is a good thing. One low number doesn't mean much. But your average starting to fall tells you something is wrong. On old trucks it's time for points, plugs, air filter, etc. On new trucks... an O2 sensor, who knows.

Did I miss anything?

 

No offence taken, but I don't see where you read "at" as opposed to "to."

Maybe the best wording would be; "fill up to the same level" each time you put fuel in the tank. I fill to the same point in the filler neck each time, and 97% of the time it is at the same pump at the same gas station. As derherr65 mentioned, it does make a diffrence which way the ground is sloping when you fill up. So if you fill at many different stations, your accuracy may be less, but your overall average will be unchanged as long as you continue to fill at "randon" pumps.

Anyways, my average over the last 766 gallons is 17.79 mpg, my current tank with 300 miles on it is averaging 18.7 mpg. The 17.79 is hand calculated and the 18.7 is according to my scangauge. The highest tank average I have ever had was 18.6 and the lowest was 16.2 mpg. My variation can mostly be attributed to the weather.

 

I find that the MPG reading is only something to look at anyway. I base my trucks mileage on several things. I consider what I'm getting in distance per tank. Usually 750-800 km per tank. That's going to be different for you south of the border types. The Canadian gallon is base on 4.4 litres instead of 3.7 litres. So my numbers will be much different than US numbers. Also I base this over several tanks not one to two. The type of driving; city vs highway & how much is towing.