Overhead computer or lack of

[roadbyte]

I just purchased a 2003 DRW 6 Speed SLT stock tires. The question I have is why is the over head computer so far off, the dealer states it has the newest update to the computer.



Took a road test to test the overhead computer, the outbound trip the computer stated that the MPG was 17 MPG after fill-up and I did the math the old fashion way there was 1. 73MPG difference in others word the overhead was overstating the MPG by 1. 73MPG. I set the cruise on 70MPG for this test.



On the inbound trip I set the cruise on 75MPG. Again I filled up and did the math. The system stated 15. 8 MPG after the math was done the true MPG 12. 798MPG or 3 MPG less than what the computer stated.



Based on my findings so far is there a fix to this problem for the 03 model.



Thank you ahead of time



Roadbyte

 

[rbattelle]

The overheads are notoriously inaccurate for fuel mileage estimation. It's best to just accept it and always track your mileage using hand calculations.



-Ryan

 

[klenger]

I've found that once the overhead establishes a MPG reading after being reset, that it doesn't want to adjust very quickly to different driving conditions. Example, if I drive 100 miles empty and then 100 miles towing, the computed milage will be higher than if I tow for 100 miles and then drive empty for 100 miles. When all driving is under the same conditions, mine seems to be within 1 MPG in most cases. I reset mine everytime I fill up.

 

[Spooled-up]

Roadbyte,

Even when you hand calculate, if you don't fill up so you can see fuel in the filler neck, you could be off by quite a bit. There is a significant air space in the rear of the tank that you can fill up by slowly trickling fuel into the neck. If you let the pump click off the first time and check it that way, there can be different amounts of fuel in the tank due to incline at the pump, etc. The only way to truly check mileage in my opinion is to fill so you can see fuel in the neck so you know the tank is filled to the top the same way every time.

I've seen some people claim their truck gets 20+ miles per gallon, which may be true, but you have to ask how they checked it. If it was checked on level ground for 30 miles on the overhead, that's entirely different than checking it consistently over an entire tank of fuel with different driving conditions.

I check mine after every fillup and the overhead is usually around 1mpg less than what I'm actually getting.

 

[Peachman]

I generally get about 1 mpg better that the computer says... Been that way since new and I'm at about 15K miles. I drive 85% highway at 63 mph and get between 17 - 18 mpg...



JT

 

[HENCHR]

My computer is pretty much right on target when I compare it to hand calculation. Of course I wish it was wrong and I was actually getting better mileage since it reads 14. 3 to 14. 5 mpg. My driving conditions never change though, mostly highway at about 60-65 miles an hour and little in town.