Setting arbitrary tire sizes for speedometer calibration

Testing new functions
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CombatDork
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Vehicle: 2013 F150 FX4 3.5L EB - 2003 Explorer XLS 4.0L

Re: Setting arbitrary tire sizes for speedometer calibration

Post by CombatDork » Fri Dec 22, 2017 8:19 pm

Assuming you already know the Tire Size field, then ensure you're calculating the tire size correctly.

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Weekend
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by Weekend » Wed Dec 27, 2017 7:53 am

CombatDork wrote:Assuming you already know the Tire Size field, then ensure you're calculating the tire size correctly.
I'm test with predefined sizes in Forscan, also i'm calculate needed size - all time after steps described here, i'm has error - incorrect params in BCM.
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jjakre
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by jjakre » Fri Jan 19, 2018 7:30 pm

is there a new spreadsheet to do this now or will i still have to do the math? i got a 2017 F150 that i have changed the tires from 275/55/20 to 285/60/20 and my mileage and speedometer is out. anyone have a fix for this?

Sally
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by Sally » Thu Feb 15, 2018 11:50 am

i have done speedo correction with HP Tuners on a 2017 Ford F150 Raptor cause we put 35x12.5x22
after that i got wrench light with DTC U0422:00-2F in PCM and P160A:00-AF in TCM

The only way to fix the wrench light is re programming BCM with IDS and do Powertrain ->Service Functions -> relearn vehicle data with IDS.

dose anybody know a solution to succsesfull adjust speedometer?

thanks

M.

Dordogne
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by Dordogne » Sat Mar 31, 2018 9:16 pm

Sally wrote:i have done speedo correction with HP Tuners on a 2017 Ford F150 Raptor cause we put 35x12.5x22
after that i got wrench light with DTC U0422:00-2F in PCM and P160A:00-AF in TCM

The only way to fix the wrench light is re programming BCM with IDS and do Powertrain ->Service Functions -> relearn vehicle data with IDS.

dose anybody know a solution to succsesfull adjust speedometer?

thanks

M.
To all of you experiencing the P160A DTC, FORScan is now able to perform a "Module initialization/Relearn vehicle data" on the PCM. This seems to do the same thing that IDS can do:

Image

You need to set your desired tire size,restart, perform the "Module initialization/Relearn vehicle data", restart, clear P160A DTC and you should be good to go.

Apparently, some vehicles also need a TCM relearn performed.
SteveInWV wrote:I have a 2013 F150 and cannot get this to do anything with my truck. I just had 295/60 R20 Nitto Ridge Grapplers installed on my OEM 20" rims. I've tried changing the pre-canned settings, and a customer setting using the calculator, and no matter what I do, my speedometer is 3 MPH slow.
Any thoughts?
If it can be done with a tuner, which I have read can be done, I have to believe that it can be done with Forscan.
AFAIK, this can only be done on 2015+ F150s that use what I call the "current generation" of as-built and modules. Nobody's been able to get it to work on a 2014 and older model year F150.

sleepy
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by sleepy » Wed Apr 25, 2018 7:57 pm

Is there a coded database of codes?

Dordogne
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by Dordogne » Wed Apr 25, 2018 8:02 pm

sleepy wrote:Is there a coded database of codes?
No need, just use the calculator. The precision you can set it is literally to the nearest millimeter of tire circumference.

seijirou
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by seijirou » Mon May 07, 2018 8:25 pm

I just poked at this for the first time last night in my 05 excursion and found the same thing, only canned tire size options but also had an "other" option and I couldn't imagine up any use for that.

When I edited the HEX directly I received a warning about a failed checksum and continuing anyway resulted in the module saying that the value was an error and it also spit out a DTC saying the ABS module was broken so I didn't even bother trying to test drive it, I just set it back to the canned tire size.

Anyway, I haven't tried it yet but one of the things you may be able to do is adjust the tone ring value. Mine is 120 which my assumption would be 120 pulses per revolution. You can't physically change the ring but you can change the expected pulses which changes the calculation. If you change the config to 108 (assumed pulses per revolution) that is going to make your ABS module think you're going faster by 10%, if you change the config to 132 the ABS module will think you're going slower by 10%.

Again assuming my assumption is correct, using this you can get the % change of your old tires to the new ones, and then adjust the tone ring config to create the same but opposite change. Bigger tires slow down your drivetrain, so if they slowed it down by 10%, you need to compensate by lying about the tone ring size by 10% and set it to 108 (120 - 120 * 0.10 = 108). If you end up with a decimal you'll just need to round it off to the nearest whole.

Not tested, this is all just bench theory after looking at this on my own truck last night.

banewby17
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by banewby17 » Mon May 14, 2018 3:12 am

Has anyone gotten this to work on a 2014 F150? I am having no luck, but I'm sure that I'm executing the guide as intended.

f-wolf
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Re: Setting arbitrary tire sizes for speedometer calibration

Post by f-wolf » Mon May 14, 2018 6:31 am


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