6.7 speedo correction help please

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12-03-2019
gerry_foster

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6.7 speedo correction help please

Hello all!

I've read though may posts on this topic and tried what i thought to be the correct route.

2012 f-450

stock tire size 245/75 17, new tire size 255/70 22.5

stock file has 655 rev per mile.

dash reads 60 MPH, GPS reads 68 MPH.

changed rev per mile from 655 to 578, set use VID to Disable.

uploaded tune (write calibration to ECM, write entire to TCM).

Speedo has not changed at all, still the same 8mph offset. Please let me know what i might be missing?

files attached, stock and modified.

Thanks in advance, Gerry
12-04-2019
gerry_foster

Anyone? :cool:

Quote:

Originally Posted by gerry_foster

Hello all!

I've read though may posts on this topic and tried what i thought to be the correct route.

2012 f-450

stock tire size 245/75 17, new tire size 255/70 22.5

stock file has 655 rev per mile.

dash reads 60 MPH, GPS reads 68 MPH.

changed rev per mile from 655 to 578, set use VID to Disable.

uploaded tune (write calibration to ECM, write entire to TCM).

Speedo has not changed at all, still the same 8mph offset. Please let me know what i might be missing?

files attached, stock and modified.

Thanks in advance, Gerry
12-04-2019
gerry_foster

Hello Gerry,

Our Ford engineer has reviewed this. In this particular vehicle, this functionality will not work. In this vehicle the Speedometer is controlled through the BCM which we do not support.

Chad Stowell
HP Tuners LLC

FYI, if you are trying to do this on a 12 powerstroke.

Looks like the only option is an inline hypertech module....

Quote:

Originally Posted by gerry_foster

Anyone? :cool:
12-04-2019
JaegerWrenching

You can use Forscan in the later trucks to correct this issue. But there was only so much room for correction before it'd throw a code. I think someone did solve this problem but not 100% sure.
12-06-2019
Higgs Boson

yes, forscan works
11-02-2022
Tiffo60

I would love to know how FORScan works because I can’t do anything that doesn’t trip the wrench light on my 15 f250 and it doesn’t matter how many pcm relearns I do. I’ve read threads all over saying you have to use FORScan but not one post showing that it actually worked.