Speedometer on new 07

[uhpilot]

My speedometer on my my 07 250 doesn't read right.

My truck has a factory lift kit with 35x13.50r20 tires.

When I drove it home the first day I was on the interstate and blowing by folks at only 65-70mph. I knew that wasn't right. I had to take the truck back to the dealer a couple days later and while I was there I had them reset the computer for the tire size. They said it should've have been done but since they were doing the reflash on the computer he updated it for the tires.

Well it seemed a little closer than before but not right. So I got out my gps and checked it against that;

At 30mph on the speedometer the gps read 32-33
At 50 the gps read 55-56.
At 70 the gps read 78-79.

I know this system is all electronic so could it be a bad speed sensor or something.

It wouldn't bother me as bad if it were a constant difference but it varies more as you increase speed and I drive in a lot of small towns where 4-5 miles over the limit might get you stopped.


Ricky

[uhpilot]

Droppped it off at the dealer to have them check it. I told them to check the sensors since it was an inconsistant difference.

I'll keep you posted.

Ricky

[mgardner28]

I've noticed the same with my 06 F250 no lift. What did they tell you?

a factory lift. That was something that was put on by the dealer. It will be off more the faster you go. You can buy a little control box from super lift that will correct that. Also you can reprogram your pcm for diff tire sizes.

[lilredpowerstroke]

It is constant. Its just off by about 10%

[D'Mann]

Look at it this way, since it's reading low you aren't putting as many miles on the odometer as you are actually driving. That's better than it reading high and putting more miles on it that you are really driving.

[TexasKingRanch]

Originally Posted by uhpilot

My speedometer on my my 07 250 doesn't read right.

My truck has a factory lift kit with 35x13.50r20 tires.

Dealers don't normally recalibrate speedometers after they lift a truck, guess you found that out.
Now if they calibrated the computer for 35" tires it may still read wrong, because some 35" tires are actually taller than that due to the type of tread. You're going to have to measure the height of the tire and then have them correct it based on that. But it sounds like they got it pretty close, and just need make one more adjustment.

[RedneckBMXer24]

no bad sensor, or anything, its way too consistant, chances are if something was messed up in the computer the speedo wouldnt work at all, or would be reading very weird. that is a speedo that isnt calibrated right.