Setting arbitrary tire sizes for speedometer calibration

Testing new functions
rcrayj
Posts: 1
Joined: Sun Oct 13, 2019 8:24 pm
Vehicle: 2013 F150 SCREW 3.7

Re: Setting arbitrary tire sizes for speedometer calibration

Post by rcrayj »

I have a 2013 F150 and I adjusted line 726-45-01 to correct my speedometer.
I used the spreadsheet to calculate my tire size difference and used the code it spit out. I am within 1 MPH of GPS speed.
RobSMITH3
Posts: 8
Joined: Tue Jul 07, 2020 11:31 pm
Vehicle: 2016 Ford Mondeo Ecoboost 2.0 240

Re: Setting arbitrary tire sizes for speedometer calibration

Post by RobSMITH3 »

Can anyone tell me which line corrects a Mondeo (UK) / Taurus (US) speedo.
I am trying to change 726-12-01 in BCMii but its having no affect.
Changed 235/50/17 for 245/55/17 and the speedo's 10% out under-reading.
Had a speeding ticket before I realised. 44 in a 40. £100 Boo Hoo !
Inserted it via IPC tyre size and also directly into BCMii line edit.
Dial speed remains the same againt GPS.
Am I doing it wrong or am I on wrong value.
Changed 07EB to 089B and was hoping to tweak, but no affect.
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

In the latest Forscan you can change rev per mile and I was able to zero mine in to almost perfect with a setting of 2174 for my 235-50R-18 size tires. I had tried the other way of adjusting BCM 726-12-01 but that didn;t work for me. When I entered the 2174 it adjust the middle 4 figures in 726-12-01 on it's own. I had been wrestling with that for about two years until this ability to change the revs per mile came along. Determine your size of tires and enter the calculated numbers. If still off you can add or subtract to your Revs per incrementally until you zero in
RobSMITH3
Posts: 8
Joined: Tue Jul 07, 2020 11:31 pm
Vehicle: 2016 Ford Mondeo Ecoboost 2.0 240

Re: Setting arbitrary tire sizes for speedometer calibration

Post by RobSMITH3 »

Thanks for the post, Where can you make that change.
I've found Wheel circumference in IPC, this alters 726-12-01but has no effect.
also written directly in BCMii to change 726-12-01 value, still no effect.
What module do you insert Revs per Mile Please.
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

I found the tire circumference in mm in BCM - Not the BCM Asbuilt.. This BCM has lines for various things you can turn off and on and enter values. Just click on the the line and enter you tire circumference in mm. If you are the US it may be in some other format - Inches or whatever - I'm not sure. Mine is 2174 and the line in BCM Asbuilt 726=12-01 (middle numbers) changed to 087E. This is in the new Forscan for my 2015 Lincoln MKC. Other vehicle may or may not have this ability. Mine was near the bottom of that page.
RobSMITH3
Posts: 8
Joined: Tue Jul 07, 2020 11:31 pm
Vehicle: 2016 Ford Mondeo Ecoboost 2.0 240

Re: Setting arbitrary tire sizes for speedometer calibration

Post by RobSMITH3 »

Thanks, already tried that.
It altered the 726 line, but had no affect on speedo.
Still playing
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

Did you do a relearn?
RobSMITH3
Posts: 8
Joined: Tue Jul 07, 2020 11:31 pm
Vehicle: 2016 Ford Mondeo Ecoboost 2.0 240

Re: Setting arbitrary tire sizes for speedometer calibration

Post by RobSMITH3 »

Sorry to seem stupid ( but I must be)
How do you do a "relearn"
RobSMITH3
Posts: 8
Joined: Tue Jul 07, 2020 11:31 pm
Vehicle: 2016 Ford Mondeo Ecoboost 2.0 240

Re: Setting arbitrary tire sizes for speedometer calibration

Post by RobSMITH3 »

I did remove battery for an hour so the PCM would clear, it had no effect.
RobSMITH3
Posts: 8
Joined: Tue Jul 07, 2020 11:31 pm
Vehicle: 2016 Ford Mondeo Ecoboost 2.0 240

Re: Setting arbitrary tire sizes for speedometer calibration

Post by RobSMITH3 »

Just found the reset functions. In the spanner section.
Is that what you meant.
Reset Transmission values and the PCM module.
Took it for a spin, no effect.
Have a DTC from PCM and ABS due to my tire size increase.
245x55x17. I make that 2169mm circumference.0879 Hex.
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