[Watchmaker]

I posted this in a much longer post but wanted to get to the heart of the matter. My odometer seems to be off by a large percentage.

I used an Iphone gps app (Speedmeter) and reset both to zero at the same time. When the truck said I had traveled 25 miles (on a straight highway) the gps said I had travelled 33.9 miles.

This seems to makes sense as the truck says 19 mpg but with the new calculation I get 25.76 mpg which would be much more inline with expectations.

For those who are getting less than expected mpg have you checked the accuracy of your odometer?

Sorry if I'm bugging you guys and girls but I find this very strange and wanted your input.

Thank you.

 

[jmperlik]

@Watchmaker - from you other post, I take it you swapped in larger tires?
=> If so, you can calibrate your odometer via FORScan described in #4 of Speedometer Calibration
=> If you don't know about FORScan, read up here on: START HERE: New FORScan user education

 

[Watchmaker]

I didn't think moderately larger tires would have that big an effect. I'll look into FORscan. Thank you.

 

[jmperlik]

@Watchmaker - I agree that a variation of > 35% sounds pretty high, but seems consistent w/your verification technique.

• I'd try running you old tires size vs new tire size thru that online calculator to see if it comes up with the same ratio
• @kdjasper (former moderator) was the expert on this topic but he hasn't been active on the forums since March 2020
• Good news is that you can dial in the correct ratio w/FORScan, as @kdjasper helped @wreedsvt within that thread

 

[wreedsvt]

That seems to be off a little much. If you have Facebook, there are F150 groups and you may be able to find a guy in your area that will come help you program it. I help people all the time around me here in Houston that do not have or know much about Forscan.