Speedometer Calibration

See photo I have attached with a screen capture of my personal FORScan spreadsheet. I have not applied this change yet, just researched how to do it a while back in prep for whenever I upsize my tires.

Here is the URL within the screen capture (Ford As-Built Tire Calculator v3.0) -->
https://docs.google.com/spreadsheets/d/1mWnuQZlDTUGjKjmJje1QJIR8Z2c7Kf8KBZxKnw_8EqU/edit#gid=0

@wreedsvt I have used the calculator for you to determine you should change as follows (as a starting point of calibration)...

BdyCM as built
726-12-01
Changed Value = xxxx 0A3B xxxx

See attached screen capture below supporting this...

Well, here is what Hypertech actually states on their product page: "This module is perfect for vehicles with computers that don't allow for tire and gear ratio correction"--see attached screenshot below. We are driving a vehicle that does allow for tire and gear ratio correction via FORScan.

It is perfectly fine if you want to get a Hypertech device to correct for tire size change. Keep in mind that the inline calibrator from Hypertech requires you to disassemble your dash to put the thing in (http://www.hypertech-inc.com/ProductManuals/inlinespeedo/730125_VSS_Instlltn_Prcdr.pdf). A lot more invasive and difficult than using FORScan.

By the way, I am more than double the age of the internet, and I think @wreedsvt is as well, so neither of us are new to the internet, we are just suggesting another and lower cost option of correcting for tire size change. Now you can do what you want with this information, and make your own informed decision on the approach you want to take.

The members of this forum are all very supportive to one another in providing knowledge sharing and assistance, and we understand that people will select different options based on what their personal preference is. For example, with disabling Auto Stop-Start (ASS), some guys prefer to take apart their dash and install an inline unit such as https://www.autostopeliminator.com, others disable via FORScan, and others like wreedsvt disconnect the BMS cable under the hood--all three options disable ASS, but in this case the inline solution still retains the on the fly enablement of ASS in case you're in situational driving where it would be beneficial to have it enabled--so the inline option provides more feature capability over the other two options. In the case of Hypertech vs. FORScan, I am not aware of any benefits the Hypertech unit provides over FORScan and comes with the risk of damaging dash components with the disassembly and reassembly of the dash to perform the install.
@yokev -- report back on how your Hypertech install and configure goes so that others can benefit and learn from your experience--thanks!

Yeah I got that value too, I will try tomorrow. I did have to do PCM and TCM relearn to make CEL/wrench go away.

kdjasper said:

@yokev -- report back on how your Hypertech install and configure goes so that others can benefit and learn from your experience--thanks!

Click to expand...

I was initially a little scared about popping my cluster out, but after watching the instruction video it appeared uber easy. Literally took me 10 mins from tools on floor, to the unit in and tools back on floor.
They have you program it on your computer first(and it also updates itself if need be), where contrary to hand-helds, you simply put in your stock tire size, and your new tire size in the next column.
I hooked up my old Garmin Nuvi after I installed it, and surprisingly it shows it being SPOT on.
Again, with at least my experience with hand-helds, the speedo is never spot on. I've taken the measurements off the manufacture's site and used 'em, and I've also used chalk on the ground to get my tires exact measurement, and I've still been off a couple mph at freeway speed.
What makes the accuracy of this thing more silly, is it just uses the generic measurement for your tire size. Obviously every manufacturer's tires measure out differently, but again, my speedo is spot on, from 25mph up to 80mph-which is where I stopped comparing