I guess because it is mentioned a few times here I need to revisit a thing or two about Speedometer calibration

ALL...every single one... of the manufactures that has a speedometer, ABS, and transmission computer controlled and getting the speed signal from a remote sensor outside of the transmission has some way to adjust and calibrate because they all can have various "Factory" tire sizes

We found with the 99-04 versions that the range of adjustment/calibration was limited to 29 inch diameter (high rev per mile number) up to about 35 inch diameter (Lower revs per mile) IIRC the lower limit was 601 rev per mile

It seems the 05 and up have an even tighter range of 31-35 inches

Some programmers can change the value in the PCM to "calibrate" the speedo for tire changes but most are limited to what the Ford tech can do. Some are sophisticated enough to exceed the factory range, most can not.

TrueSpeed makes a device that intercepts the factory tone ring signal (pulses) and converts them to the correct pulse train for the tire diameter you have no matter how large or small. In fact it will store two different tire sizes so you can run "winter" or "summer" tires of a different diameter

There are no programming codes or processes that a Ford tech can do to FRY a PCM...

That said, there are times when programming a PCM, (just like updating (flashing) your computer you are reading this on ROM BIOS)--- that if you do not complete the action, halt it mid cycle, disconnect the umbilical, or loose power then the PCM requires a Hard flash and the Ford tech does not have the equipment to do that.

 

"FRY" may have been the wrong verb to use. Maybe I should have said f**ked my computer.
They (Ford dealer) could not calibrate my speedo at all. They tried to put in a different "factory" tire size that was closest to the tires I had and after their failed attempt, my truck sat for over 2 weeks waiting for the new computer. It may have been that I had an incompitent tech, but this guy is supposed to be their "computer" guy.

I bought an Xcal2 and had it calibrated via SCT's software. Even that posed it's problems and after several calls to SCT we got it right, but had to change how the speedo gets its signal. It no longer reads from a speed sensor, and it is now reading some calculation directly from the PCM.

I could tell so many stories, and give so many examples of poor workmanship, and poor knowledge from trained techs you'd think I was making it up, but I'll save those for another thread, some other time.

 

DD of the D

I knew what you meant...just wanted to say what I know so the newbies don't get all parinoid...there are solutions

Sounds like you and I could swap horror stories on incompetent technicians

 

Which ones are sophisticated enough to exceed the factory range?

 

You realise this is a 2 1/2 year old thread you just dug up ?
BTW it sounds like 5Startuning is THE MAN to go to if you want a V10 tuner!

 

I realize it is an old thread, that goes to show how much searching I did. Also the question I asked about which tuner is sophisticated enough to adjust tire size to 37's still has not been answered. I have been searching, calling, emailing, even the big companys don't give a convincing answer (they say things like "it should work". BTW I got the X3 from Mike and the 87 tune is awsome. However I have adjusted the tire size (revs/mile) from 560-660 (I currently have the stock conti's (628)), and there was no change in speedo (used GPS) or odometer (I got the same mileage on the odometer on my drive to work, to and from an exact spot). And I didn't notice any change in the transmission performance with the change in revs/mile (thats hard to measure). Just to be clear I did these tests by only changing the revs/mile in the X3, I had the stock contis on the whole time. So I wonder what the revs/mile in the programer does? And I haven't heard which programers can change all this. And is it ok to use a truspeed/speedwizard with the X3 (do I still change the revs/mile in the the X3 or leave it stock and the truspeed handle it? I know this is a confusing topic, probably why we find it hard to get a straight answer.

 

I have a 2001 F250 V10 with a 5 Star SCT X-3 tuner, and it will not adjust the tire size. I use the TrueSpeed and adjust it with a GPS. It works great.

The Merlin Speed Adjuster is another option.

Superlift TruSpeed ratio converter

Truckblog - How-To Install A Speed Wizard