I've noticed throughout the 6.7 forum, and I'm sure it is used in all forums,
that folks tend to use the overhead info for their MPG calculating. I've found
that my overhead is so far off on the mpg that I look at it and wonder why
Dodge even put the mpg feature in there. Folks that go by it as gospel are kidding themselves. Or maybe they got lucky and got one that really is accurate.
I do wish the info was accurate,, I'd be getting several MPG better and I wouldn't have to hand calculate.

If anyone can tell me how to tweak, adjust, reflash, etc, etc, to get the overhead to read accurate, please tell me cause it would be an excellent feature then. Until then Dodge ought to be ashamed of themselves for adding the feature. I love being wrong and being corrected if it'll help me so
shoot me and get my straight on this if I'm looking at it all wrong.

jerry

 

I agree with You on the mpg reading on the overhead console, mine has been off by 10 mpg before.

_____________________
2007 dodge 4wd
4 door
cm skirted bed
6-speed auto- love it

 

>> agree with You on the mpg reading on the overhead console, mine has
>> been off by 10 mpg before.

Yep mine always reads better mpg than I really get,,, never ever worse.

j

 

Same here!!!!!

 

Mine is 1.5 to 2.0 less than overhead shows

 

Mine too, 1-2 MPG less..... BUt it stays consistent with how far off it is.. LOLOL If I subtract 2 MPG it matches my Hand calc...

 

It's Dodge trying to scam us 24/7...
I think that it is calculated by the throttle position and % of load the engine has.... Not 100% sure, but I think I read that somewhere.

 

Wouldn't it be nice if someone would figure out how to
calibrate them to be accurate to like +/- 0.5 mpg.
If they are all off one way or the other a consistant
amount seems to me some electrisacal geek ought to be able to
figure it out.

I have 59,000 miles on my 07 and while non-towing and towing different
weight trailers in many different type terrains and speeds, I never even thought about mine being off X amount consistantly in all scenarios. I just assumed the display readings was all over the map with no rhyme or reason.

jerry

 

Question from the new guy... Where does the display get the fuel consumed for the calculation? I assumed it would be from the ECM which just knows how much it "asked" for. Or is there an actual flow sensor somewhere instead of what the ECM could put together from what it needed for its combustion fueling calculation. Am I even close?

 

Kurt wrote:
> Or is there an actual flow sensor somewhere instead of
> what the ECM could put together from what it needed
> for its combustion fueling calculation. Am I even close?

I don't have a clue but like any curious person I've thought
many times how the thing works as I drive along.

I would think that if it had a "flow sensor" the mpg reading would
be almost immediate with the changing of the speed thus doing
55mph and then floorboarding the throttle that would cause instant rise
in mpg or vice versa.

I've niavely thought that there might be a correlation between the dash
odometer and the gradual fall of the fuel gauge which would probably
be quite a lag in the overhead reading. But I imagine it's more
sophisticated or complex than that.

Offtopic:
I have found out several times when running low on fuel, while running on
my main factory 52 gal. tank (chassis cab), that when the
"low fuel chime/light" sounds off, the miles left on the tank usually reads
75 on that feature of the overhead.
From the looks of the fuel needle near the red line I don't think it would
go 75 miles and I certainly don't want to find out the hard way. Several
times I've had to pull over on the shoulder of a busy freeway get out
and open my aux tank inline valve located at the tank on the bed.

jerry

 

I reset mine EVERY time I fill up.
To date, the worst it's been in error is +1.2 mpg. Typically, it closer to +0.5 mpg
Read somewhere on internet, that if you reset it EVERY time you fill, the reading is much more accurate. Seems to work for me for past 6K miles

 

^ Right! Also if you hook up a trailer you have to reset it (before you tow it).

 

Mine runs about 10% high

 

Must be a coincidence ? someone surley has a truck that shows less than they are actually getting.

 

Yes me....Here's what I think happened....I'm from Canada and we are stuck with the metric system which is so many liters per 100km. I'm 54 and the metric system doesn't mean anything for the people that old. If you telling me we received 124 millimiters of rain yesteday, I don't have a clue.
Now, I don't think D/C bothered to adjust the mpg for me, since with the old system, our gallon, ( imperial ) was bigger than the US gallon. No matter what, I have to make the conversion from metric to US to find out how many MPG my truck is doing. I have a calculator and a conversion table in my truck.