How to use FORScan to adjust tire size

[pagan696]

Thank you to all who have been contributing to this thread, it has been very helpful.

I have a 2020 f150 xlt stx 2.7v6 EcoBoost 4x4 and recently upgraded tires from the factory 275/55-20 dynapro2 to 275/60-20 cooper at3 4s. My stock bdycm was 099E and I switched it to the 09F2 value recommended by the spreadsheet. My speedo is perfect with the change however, the shift points still seem a bit off. It's nowhere near as bad as before the forscan change. That had me thinking, "What have I done to my truck?!". I only changed the single value in 726-12-01 and it kept. No error messages or warning wrenches either.

Is there something else I need to adjust to get my shift points to feel more fluid? It feels a little "herky-jerky" compared to previous tires and programming.

Is there a better value to enter into forscan than the one I chose?

Do I need to do the unhook battery for x-amount of time and let it relearn my driving style with the new tires? I drive a little more conservatively and the ride just seems a little off from what I think it should be.

I appreciate any feedback.

[Guido80ss]

Good morning guys I ask you for help, I have a 2018 European transit mk8 AWD, I follow your procedure, I change the diameter of the tires, I update everything but the errors don't come out, I always have the van at 100 km/h speedometer and 95 gps i am very disappointed what can i do can you help me thanks

[Riddlemethis1]

Really should state for which vehicles this works on as I don't have the same start menus. Only way I can change is via the BCMii main there I just stroll to change tyres ..

[dontpannic]

Hello everyone. Sorry to post without introducing myself!!

I have a MK3 Focus in the UK (very late 2012 build, 2013 registration) and currently the speedometer is over-reading - it's not by much, but it's enough that if I'm using the cruise control or speed limiter, then I'm below the speed I actually want to do. As an example, setting the cruise control at 52mph is, according to the GPS, 49-50mph.
It's not a lot, but then if I want to set the speed limiter to 50mph (as it only adjusts in 5mph increments), I'm doing too slowly and end up holding up traffic.

It's been a long day, according to the tire size calculator, my current circumference is 2019mm (215/55/R16). Am I looking to adjust this up or down to compensate? Is this a figure you can just 'play around with' or are there set values that the computer will accept?

Cheers,
Nick

[jester26592]

you have to x0,967 to get the correct data in mm after calculation... like mine 205/45R17 = 1935x0,967=1871 and this is for ford Fiesta MK8 from 2020
I enter 1870 and then its worked

This worked perfectly, Thank you!!

[makamer]

I know this has been asked many times but I have not seen a definitive answer.

I increased the size of my wheels and now my speedometer is off. I tried setting the size in Forscan but then received an error about the BCM not being able to read the data. I would need to do this again to get the exact error. I had to revert back to the original tire size to get the error to clear.

Is there a way to do what I need to get my truck calibrated properly?

[ddwrt3400]

The option
"TCM Module Initialization/relearn vehicle data does not show for me?

Any solutions?

[Ecmbuster]

Answered through this double post.
https://forscan.org/forum/viewtopic.php ... 781#p89781

[jseay]

I'm trying to update the axle ratio and tire size on my 1999 2WD Expedition so I can correct my speedometer. I cannot figure out how to do this with my Forscan for Windows Extended License.

I have searched the Forscan Forum, FTE, and the ExpeditionForum.com and have not found anything close to my vehicle.

I can view PIDs to display the axle and tiresize from the PCM but under Configuration and Programing it only gives me 2 GEM options, no PCM.

Is this impossible with my vehicle and Forscan or am I missing something?

[Ecmbuster]

The PCM adaptions / programming features need to be investigated but quite certain that model is too old and may not have the adaptations / abilities / changes within the engine management system.
If it is possible, the PCM would need to be programmed with those chages (providing the changes are supported).

The Hypertech Speedometer Calibrator reprograms the BCM (Body Control Module), not the PCM (Powertrain Control Module). The Hypertech device is used to maintain speedometer accuracy.
ie:
https://www.amazon.ca/Hypertech-752501- ... B006RQ44O4

Cannot support an axle ratio change modification..pdf

(14.22 KiB) Downloaded 558 times

Post your results and tests with images.