Anyone else's overhead computer way off?

[Po' Riggity]

Ive noticed, from hand calculating my last couple tanks of gas, my overhead computer is reading way low in average economy. . anyone else have this problem? My last tank, hand calculated, was 18. 7 mpg, and the over head said 14. 1. Confused, I am.

Scott

 

[JPereira]

I am new to the Dodge. I have around 1700 miles and the overhead has shown from 15. 9-16. 2 and hand calculations have been 16. 3. I am very happy with the accuracy.



Do you reset yours on every fill up?



I have not reset mine yet and am not sure if that is why iit is getting better.



1st tank overhead 15. 9 and hand calc 16. 3

2nd tank overhaed 16. 2 and hand calc 16. 3



We will see what the 2rd tank has to say.

 

[b737jets]

Yeap... ... ... ... .



Mine is apprx 2. 5 mpg off and I allways reset mine after each tank full... ... ... .



another thing I have notice is why does my trip computer show that my range on a tank never shows better than 470 to 500 mi's even though I'm able to tank a full load in excess of 650mi's... . ??



My 02 HO trip computer was right on the money what gives I'm gonna need to speak to the 5 star guys. I guess the 02 would alway be about . 5 off on mpg but right on the money as far as range goes full load diesel would show anywhere from 635 to 655 mi's



Oh well ... ...

 

[roperteacher]

Mine ran about 2MPG off the first 7,000 miles, now it seems to be right on. . and my mileage has been steadily increasing!!!! Just shot up when I turned 8,000...

 

[Po' Riggity]

Ive noticed that about my computer. . it shows 432 miles after every fill up, but I know I can get more. . it now reads that I will only get 222 more miles out of the tank. . and Ive only traveled 170 miles on this tank so far, and still have 3/4 of a tank. . Im guessing something is up with my computer. . Its off by a bit. . and its gonna bother me... But oh well.

Scott

 

[MarkH]

If i remember correctly according to the owners manual the drive to empty actullay leaves about a 8% "reserve" in the tank so you can still make it to a station even though your DTE # says "empty".

 

[HOCummins04]

Mine has been off as much as 4MPG. Hand calculated fillup was 19. 7 and overhead was something like 15. 8 or 15. 9. It is never right, at least for now. Having had significant reliability problems with my 01. 5, this issue kind of pales in comparison. When DC sent the new owner survey, I made note of it. Some guys the computer is pretty accurate, others like mine are off in the tall grass.



My 2000 Caravan has actual current economy in addition to AVG economy. Really helps you see what the vehicle does under full acceleration, climbing hills, etc. Wish this truck had that too. But, if it is going to be off as much as my AVG is, not much point to it.



Has anyone ever verified the accuracy of the temp? Makes ya wonder.

 

[TCrawley]

I thought I was the only one with a huge difference from what the overhead says to what I hand calculate. My overhead says 16. 6mpg and i hand cal. 20. 8mpg. I am not worried about it as the numbers are better than the overhead.

 

[KHogan]

My 3rd gen reads lower than actual, but it's only about 0. 25 to 0. 5MPG off (fuel guage also operates very linearly, so the remaining DTE is pessimisstic, but fairly accurate). My 2nd gen read 2-3MPG HIGHER than actual (fuel guage was useless... the more it moved towards empty, the faster it moved! DTE feature was useless).

 

[Ftuttle]

Overhead computer - DTE

I've noticed the same w/ my computer calculating 508 miles until empty - no matter what mileage I've gotten previously (pulling, empty, city, highway... ) - My mileage calculations have been almost dead-on.



Reading the manual, it states that there is meant to be a 10% difference in "Empty" and actual - given a 35 gal tank ('03 HO manual trans 2500 crewcab shortbed), this would be 31. 5 gal used. Given 18 mpg (typical - most time now w/ 19K I've been getting 18. 5-19 riding empty combo hwy/cuty) the calculator should read 567. I've NEVER seen it above 508.



My fuel gauge light turns on with 26 gallons used (9 gallons remaining). Always.



I know that Dodge is probably doing us all a "favor" by trying to ensure that we don't run our diesel engines dry, but come on!



-frank t

marysville, oh

 

[Nine Ball]

my 3500 reads 507 miles available when I fill up the tank (35 gal)

 

[Iguide]

Computer

Yea mine is way off also. As much as 2-3+ gallons less with hand calc. that the overhead. Haven't checked it since winter though. To bad that darn thing said I was getting 26 to 27mpg.

 

[Jengle]

Mine started out in the . 2 difference one way or the other. Now with 18k on the truck, it is consistently 2-3 mpg lower than hand figuring shows. DTE seems pretty consistent though. Right about 600 each time I fill up. And I get about the same amount in the tank when it shows under 10 to go. Haven't had the nuts to run it to empty yet. This thing about being Found On Road Dead with my new Dodge kinda gets in the way.

 

[Po' Riggity]

Well, Im glad Im not the only one getting innacurate readings from my overhead. . Im not too worried about it now. . I will be letting DC know if I get my new owners survey soon.

Scott

 

[John - K5AWO]

My experience with the overhead computer is with a '90 Plymouth Voyager. It had both AVG and Instantaneous readouts.



I found that the Instantaneous to be very accurate. The average though depends on how you have been using your right foot over about the last 75 miles. It does an averaging computation based upon the most recent 75 miles. Not the average over a full tank of gas.



Resetting the computer to zero with each tank destroys the history that it is averaging on. It has to start from zero again. I finally quit the zero out function unless I was just starting a long trip.



My experience has been that if left alone, it will be very close over the long haul.



Measuring from "tank to tank" is pretty much a futile exercise. The history base is too short and the "completely full" level is not really known for sure.



You never really know if the tank level is exactly the same. The truck has to be in exactly the same position, the air bubble problem, etc... Also, unless you use the same nozzle everytime, you will get different readings. Add to that, the fuel expansion with temperature. MPG is not an exact science and never will be for all the above reasons. Best you can do is average out over 5-10 tanks or keep a continuous record.



My 2 cents worth... :-laf

 

[Po' Riggity]

Ive now started a continuous record on paper, which records the date, price per gallon, number of gallons put in, price of total gallons, and miles per gallon.

Scott

 

[HOCummins04]

For years, I have kept a log of each fillup. Odometer, Trip (if equipped), Date, Place, Fillup Y or N (to know if I can calculate accurately mileage), gallons, cost, MPG.



I usually don't calculate MPG every time, though I keep a solar powered cheapo calculator in the vehicle for doing so when I wish to. Knowing MPG helps sometimes spot performance problems before breaking down.



In the same book, I keep notes of everything I do in terms of maintenance - what I did, date, mileage since last



This serves as documentation should anyone ever wish to dispute my maintenance. I am seeing dealerships ask if regular maintenance has been done on the vehicle when you go to trade it in.

 

[Po' Riggity]

yup. . being this is my first new vehicle ever, maintenance is going to be recorded, as well as mileage and fuel consumption, now that Im just over 1000 miles, I figure its a good time to start. . And I plan on keeping the truck forever

Scott

 

[DPearson]

Mine is off by about . 2 mpg. Still don't trust electronics so I hand calculate about every 3 tanks.

 

[Iguide]

computer

John - K5AWO



That is might damn interesting. It explains a lot.