Overhead fuel mileage correction

[Jack in Alaska]

Does anyone know if the overhead mileage can be calibrated or adjusted to give correct data. What I get now is worthless.

An estimate at best. Oo.

My 2005 300C is pretty accurate.

 

[Diesel Nut]

As far as I know its not adjustable, unless maybe there is a flash. How far off are you? I don't even look at mine anymore except to get a rough estimate. At 17mpg the overhead says 24. Chips will do that.

 

[DPKetchum]

Mines always withen . 5 of correct.

 

[AJain]

When mine says 22 I'm actually getting about 19.



The difference between "indicated" and "reality" is actually more than before I got the TSB flash upgrade about a year ago. But now it indicates too high rather than too low.



aJ

 

[hearingyourlies]

As was said by Ajain, there is a TSB to flash the computer for accuracy. However, it probably does more harm than good.

 

[klenger]

Have you done any perrormance mods? If so, ...

 

[JWilmer]

I added 285 tires and that helped... its darn close now... BJ

 

[Byershome]

Mine always reads about 2 mpg lower than what I am getting.

 

[RustyJC]

As klenger said, any mods and all bets are off. I recently saw 24 MPG pulling my 5th wheel. :-laf :-laf



Rusty

 

[Dieselnerd]

As long as I reset mine at each refueling it reads almost exactly the same as hand calc. My engine and tires are stock.

 

[DPKetchum]

Yep. I reset mine ever fill up. Sometimes more often if conditions change just to see where it averages out at. But mine is dang close per tank.

 

[brods]

Jack in Alaska, did you ever have the 18-037-04 reflash? Supposedly "Improves accuracy of the fuel economy calculation in the overhead console display" among other things.



It's for engine serial #'s 57130285 to 57246361.



My overhead is usually 2 mpg optimistic (stock truck but no reflash yet).

 

[BNH4221]

Mine is always about 2 mpg optimistic. Reads 21-22 and I avg about 19-20. My wife doesn't understand how my big truck gets better mileage than her little minivan :-laf





steve