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Downloaded the latest ForScan 2.3.2.8 beta for Windows and renewed my license key (free) to see what was available. To my surprise there are many more NEW parameters within the BdyCM that are configurable.

If someone wants to test, you may now finally be able to correct the speedometer with larger tires. My exact size wasn't listed but maybe a savey member can find one (or a combination) that works.

Many settings for Tire Circumference
76 settings for Tire Dimension
69 settings for Final Drive Ratio
 

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I downloaded that last week, but did not go in far enough to find any new parameters, will have to check.
Also, when the 2015 is connected it sometimes brings up different settings than the 2018.
 

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I've never had any luck with asking for volunteers .... ;-]

I spent some time looking into it because it was a challenge. That may be enough to get someone to try it and if they do it and can document it they'll get bragging rights for their accomplishment. On both the '15 and '19 it's with larger tires I found the average MPG to being very close to matching my spread sheet calculations. The spread sheet logs the vans miles between tanks and uses a fixed percent to estimate to come up with a calculated miles per tank. It uses the same percent mark up for the van's odometer to get a calculated miles on the van. The percent markup was come up with by using a GPS to track actual miles traveled verses what was on the trip meter and odometer. If you do that with the stock tires you'll find the van's odometer is off by one or two percent anyway. I think +/- 2% is the industry standard.

For me the bottom line is I can live with the odometer and speedometer being off as long as it can be tracked for maintenance intervals. What I like about the way it is with the larger tires is the average MPG is close to being accurate. That works for me because that's not something I can estimate in my head while driving down road.

There is also no way to know how the vans multitude of modules linked by the CAN bus uses tire size in whatever form it's in, where it (or they) are stored. Another possible issue is the "Ignition Counter" getting reset" when doing the PCM Module initialization / relearn vehicle data procedure. As far as what I've read online, you do have to do the relearn procedure for any changes in the tire size to get picked up and put to use.



Edited to add .... sportcoupe Can you post a screen print of the new settings for Tire Circumference?
 

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You tried changing tire circumference, tire dimension and final drive ratio?
I looked at circumference and tire dimension and my size was not listed in either table so I stopped there. No changes were implemented. I'm a bit too lazy to get out the calculator and try to do the math using the largest circumference listed and pick a final drive ratio that might come close.

From comparing the speedo to the GPS I can see that the speedo reads 5 mph slower at 65 mph than actual speed as indicated by the GPS. Actually used two GPS sources at one point to confirm.
 

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I'd guess those clever folks over at FORscan . Org have gotten their hands on a 2020. I don't think FOMOCO has plans to let their service techs start re-calibrating transits odometers. But I could be wrong .... ;-]

The axle ratio is already stored in The AS BUILT (.AB) file as a hex value in address 726-04-01. It looked like the two transit tire sizes (235/65R16 & 195/75R16) were stored as a two digit decimal value in address 726-06-01. I could possibly see FOMOCO sticking with that address and format, and using increasing values for different circumference values.

195/75R16 -} Circumference in mm: 2195
235/65R16 -} Circumference in mm: 2235

You can open the file FORscan stores (.ABT) after you save or back up a module with Notepad or the like. You can save the module before and after making a change and compare the two files. I still don't think you'll get the odometer to reflect the change without running PCM Module initialization / relearn vehicle data procedure.

See ....
 

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  • Get the FORScan update loaded and the compare plugin for Notepad ++
  • Get everything hooked up in the van and trickle charger on van batteries
  • Plug OBDLink LX Bluetooth into ODBII extension on the console
  • Remember how to get the bluetooth adapter to communicate with FORscan
  • Disable Webroot
  • Start up FORscan and turn on ignition key
  • Save all the modules
  • See what sportcoupe was pointing out
  • Quit while I still haven't bricked anything yet
  • Compare 2019 bdycm asbuilt ori.abt to 2015 bdycm
  • Compare 2019 central config main.cct to copy of same for baseline


















When I get more comfortable with the setup I'll change the tire dimension, save it, save the module, change it back and save the module again. Then I'll compare them in Notepad ++ and see if it actually changed. FORscan , Org says somewhere that not all the options really change something.

Just out of curiosity .... ;-]
 

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Like the decor
That's the magnetic flux interior. About 95% is held up with magnets. Bed sheets and reflectix up top - black stretch mesh over the windows (acts like a two way mirror).

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I changed the file extensions on two Ford "AS BUILT" (.AB) files I had downloaded to .XML so I could view them in a browser. I found the 39 value for DWD 195/75R16 tires in the AS BUILT file for the DWD. The 46 value for the 235/65R16 tires was in the SWD AS BUILT file in the same location. I over laid the lines to show the alignment ....





That seems to validate that they use the values in the screen prints sportcoupe posted in the transit instead of the hex value of the tire circumference that the F150 uses.

If FORscan can write the other values that can be selected to the module and if the relearn procedure can correctly update the PCM ....
 
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