Modifying tire diameter, is this correct?

[TheSEARCH]

2023 XLT Hybrid FWD
Trying to confirm how to adjust my speedometer as its off with new tires plus snow tires i use . Both the snows and new tires Continental Tour 54 show 60 mph on Mav BUT is REALY 58 mph. Drives me nuts.

So I ordered the USB connector for my windows laptop A Vgate vLinker FS OBD2 USB Adapter for FORScan HS/MS-CAN Auto Switch.
BUT want to confirm I am doing it correctly , Have forscan all setup ready to go registered 2 month version trial.

So from what I found on this forum plus youtube.

I open with MODULE Tab then to BdyCM (MAKE BACKUP FIRST.) then play it, then do search for tire . Find tire circumference. Adjust to lower
number in my case. Geminis AI says from 2220 to 2162 which says that should correct the 2 mph error.

WRITE it then leave module and then is same Module Tab go to
to IPC Module Reset..... and play that.

Now to WRENCH Tab Find...... tPCM Module Initialization..... Now Play that then to TCM Module Initiation and play that.

Now DTC Tab and clear codes.

Done I THINK

NOTE .... I see some say Run or Play Others say Reboot as the terms seem to mean the same thing

First time using forscan so if not right keep as simple as possible to say what i am doing wrong or missing. Thanks for any help

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[Quest]

You would also need to do the AWD module if its 4x4

 

[TheSEARCH]

You would also need to do the AWD module if its 4x4

FWD so no . BUT since no just front wheel drive do I have it correct?

 

[Quest]

Yes, you can confirm you got it right by driving at 100kph (60mph) and compare with GPS on your phone.
The faster you go at a steady speed the more accurate the phone will be
Steady is the key here
In your case that's a pretty small adjustment, I doubt you will even notice a difference.
If you want to fine tune go 200 at a time up or down

PS: Using Metric is easier, the difference is the percentage your off at 100kph & make sure the phone has a good view of the sky
PSS:That is unless you want to drive at 100mph, that works too except for the speeding ticket

 

[Master Blaster]

Why don't you just go into engineering mode on the dash and change the AFE setting to match your actual tires? No Forscan or anything else needed.

 

[Cancunbadlands]

Why don't you just go into engineering mode on the dash and change the AFE setting to match your actual tires? No Forscan or anything else needed.

Interested
How to?

 

[TheSEARCH]

Why don't you just go into engineering mode on the dash and change the AFE setting to match your actual tires? No Forscan or anything else needed.

AFE means average fuel economy. It doesn't effect MPH of speedo according to Gemini AI.
Googling it seems to say same thing. I wish it was that easy

UNLESS Gemini AI is wrong plus google results.

 

[Quest]

Why don't you just go into engineering mode on the dash and change the AFE setting to match your actual tires? No Forscan or anything else needed.

Don't think that will change actual speed display

 

[deputylynch]

2023 XLT Hybrid FWD
Trying to confirm how to adjust my speedometer as its off with new tires plus snow tires i use . Both the snows and new tires Continental Tour 54 show 60 mph on Mav BUT is REALY 58 mph. Drives me nuts.

So I ordered the USB connector for my windows laptop A Vgate vLinker FS OBD2 USB Adapter for FORScan HS/MS-CAN Auto Switch.
BUT want to confirm I am doing it correctly , Have forscan all setup ready to go registered 2 month version trial.

So from what I found on this forum plus youtube.

I open with MODULE Tab then to BdyCM (MAKE BACKUP FIRST.) then play it, then do search for tire . Find tire circumference. Adjust to lower
number in my case. Geminis AI says from 2220 to 2162 which says that should correct the 2 mph error.

WRITE it then leave module and then is same Module Tab go to
to IPC Module Reset..... and play that.

Now to WRENCH Tab Find...... tPCM Module Initialization..... Now Play that then to TCM Module Initiation and play that.

Now DTC Tab and clear codes.

Done I THINK

NOTE .... I see some say Run or Play Others say Reboot as the terms seem to mean the same thing

First time using forscan so if not right keep as simple as possible to say what i am doing wrong or missing. Thanks for any help

Did you actually see a setting for just TCM using forscan because I can't find it on my 24 lariat hybrid?

I found PCM but not TCM.

 

[Chops]

Don't think that will change actual speed display

OP could perform an experiment.

1) Compare current speedometer reading to GPS & note the discrepancy.

2) Fiddle with the AFE in Engineering Mode and perform step 1 again

3) Is the discrepancy the same in both step 1 and step 2?

Not sure how the AFE algorithm changes the mpg reading. Thinks you’re traveling a bit further (or less further) on a gallon of gas than what the previous setting calculated?

Does it consider engine run time? If so, it can calculate the accurate mph to match the accurate mpg. Why not show that more accurate mph on the speedo?

Anyway, why don’t cars use their GPS systems to run their speedometer & odometer? Because it is illegal - not accurate enough for gov safety refs.

 

[Cherokee]

Man, you guys need to go for a ride and Fagetaboutit.

I did my gps against my stock tried Mav
I was one mph off.

Mox nix" (often spelled mox-nix or mox nix) is a slang phrase, largely adopted by U.S. soldiers in post-WWII Germany, meaning "it doesn't matter" or "it's not important". It is derived from the German phrase es macht nichts, which translates to "it does nothing" or "it doesn't matter".

 

[deputylynch]

Man, you guys need to go for a ride and Fagetaboutit.

I did my gps against my stock tried Mav
I was one mph off.

Mox nix" (often spelled mox-nix or mox nix) is a slang phrase, largely adopted by U.S. soldiers in post-WWII Germany, meaning "it doesn't matter" or "it's not important". It is derived from the German phrase es macht nichts, which translates to "it does nothing" or "it doesn't matter".

Well it does matter when my odometer is off, reading more than it should, accumulating thousands of miles over the life of the truck.

 

[Chops]

Man, you guys need to go for a ride and Fagetaboutit.

I did my gps against my stock tried Mav
I was one mph off.

Mox nix" (often spelled mox-nix or mox nix) is a slang phrase, largely adopted by U.S. soldiers in post-WWII Germany, meaning "it doesn't matter" or "it's not important". It is derived from the German phrase es macht nichts, which translates to "it does nothing" or "it doesn't matter".

Please fiddle with your AFE settings to see if your Speedo changes vs GPS. I know - “what part of max nix don’t you understand!”

 

[TheSEARCH]

Did you actually see a setting for just TCM using forscan because I can't find it on my 24 lariat hybrid?

I found PCM but not TCM.

I just did it yesterday. Yes NO TCM as that is for transmission which the hybrid used e-cvt and running the PCM under Wrench tab takes care of that.

 

[HeyBales]

AFE just applies a correction % to the value that is calculated from the values that are read - doesn't change the base values.
Screens on each side of the setting screen show you the values used.

950 / 1000 - 95%. Just a correction %.

If you really want your DTE or displayed mpg to be right on - that's your solution.
But it won't correct your inflated driven miles reading, or speedometer.

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