EcoDiesel, A Maiden Voyage

paulharvey · Jul 23, 2014

On the topic of mileage, why do the on board computers calculate the milage wrong. In the 5.7l hemi, screen says 19.2 mpg or so for last 3 fill up, but real mileage has been 17, 17.04, and 17.8 mpg. Not complaining about mileage, just wondering. Does the computer not count idle fuel use?

fordmantpw · Jul 23, 2014

It's just a matter of error in the calculation. They can't precisely figure out exactly how much fuel is used, so there is just some error in the system. The gauge in my '08 F250 is generally 1+/- MPG above hand-calced. The '11 and newer Ford trucks are almost spot on. Can't vouch for the other makes.

Diamondpilot · Jul 23, 2014

paulharvey said:
On the topic of mileage, why do the on board computers calculate the milage wrong. In the 5.7l hemi, screen says 19.2 mpg or so for last 3 fill up, but real mileage has been 17, 17.04, and 17.8 mpg. Not complaining about mileage, just wondering. Does the computer not count idle fuel use?

Dodge has always been way off for some reason. I currently have 3 Ford's and a Nissan and they are never off by more than 0.1mpg.

I have owned Hondas, GM'S, Toyota, BMW, ect and none of them have ever been off by more than 0.2 mpg.

My 03 Hemi Dodge was always off 3 mpg or so also.

Chris

94BULLITT · Jul 23, 2014

paulharvey said:
On the topic of mileage, why do the on board computers calculate the milage wrong. In the 5.7l hemi, screen says 19.2 mpg or so for last 3 fill up, but real mileage has been 17, 17.04, and 17.8 mpg. Not complaining about mileage, just wondering. Does the computer not count idle fuel use?

Ram uses a lie-o-meter. I think some of the Cummins trucks were way off too.

Diamondpilot said:
Dodge has always been way off for some reason. I currently have 3 Ford's and a Nissan and they are never off by more than 0.1mpg.

I have owned Hondas, GM'S, Toyota, BMW, ect and none of them have ever been off by more than 0.2 mpg.

My 03 Hemi Dodge was always off 3 mpg or so also.

Chris

My Ford is off .01 too. I think it the reason it is off that amount is because it is impossible to get the same amount of gas in everytime and it throws hand calculating off a hair.

fordmantpw · Jul 23, 2014

It's even worse on a diesel because it is IMPOSSIBLE to fill it to the same place every time unless you spend 20 minutes letting it trickle in so that it doesn't foam up.

dodge man · Jul 23, 2014

I've owned a lot of Chrysler and Dodge vehicles and the overhead display was always pretty close. My current truck, an 04 with a Cummins is always off a lot. It probably shows about 21.5 mpg but I get closer to 15 mpg.

fordmantpw · Jul 23, 2014

dodge man said:
I've owned a lot of Chrysler and Dodge vehicles and the overhead display was always pretty close. My current truck, an 04 with a Cummins is always off a lot. It probably shows about 21.5 mpg but I get closer to 15 mpg.

They do that so it doesn't hurt so bad when you have to pump in that black gold known as diesel! :laughing:

I know it feels a lot better filling up my diesel when the gauge reads 21 after a road trip. Then I enter the numbers into fuelly and it comes out to 17 and I come back to reality. :laughing:

Strangely, in my truck, with my normal driving, the gauge is usually off 1 MPG. On longer road trips, it's off more, usually 2-3, and I have seen it off by 4 once. Could have been a particularly foamy fuel at that stop though.

dodge man · Jul 23, 2014

It is hard to fill them up, like you say, the diesel foams. The biggest problem is mine has a Edge chip on it and that is what often messes up the overhead display.

fordmantpw · Jul 23, 2014

dodge man said:
It is hard to fill them up, like you say, the diesel foams. The biggest problem is mine has a Edge chip on it and that is what often messes up the overhead display.

Ahh, yeah, I've heard the chips mess up the MPG meter. Did your chip have any real effect on fuel economy? You hear all the stories about 5-6 more MPG, but I have a hard time believing that and think it's just folks using the gauge and not hand calcs (or rounding 16 up to 20 to make them feel better

).

dodge man · Jul 23, 2014

My truck is a 2004 and I've owned it three years. I bought it with the chip on it. It without a doubt adds power but I doubt it helps with the fuel mileage.