Speedo off by 1 MPH

[SmoothJ]

So while on bluecruise on my local highway, I noticed my speedo is off by 1 MPH. I noticed this while I was on Google Maps and its little MPH indicator while in active navigation.

This was also tested on my wife’s Equinox EV and it seems to be right on target.

How can I fix it or is due to me having nearly 37K on the ODO and need a new set of tires?

Sponsored

 

[chriserx]

I noticed it on my comma, and I've had it installed since 1k miles, it's just how they shipped it.

 

[RLXXI]

Ford spec use to be +- 7mph was considered normal unless it had a calibrated speedo like a police interceptor would have.

 

[molsonmatt]

Ford spec use to be +- 7mph was considered normal unless it had a calibrated speedo like a police interceptor would have.

Yes I had a ‘17 lariat with an analog speedo that read about 4mph slower. The display also had an optional digital speed display which I always had on as it was right on the money. I asked ford about this and they said there was nothing that can be done about the analog speedometer as it was within spec.

 

[RLXXI]

Yes I had a ‘17 lariat with an analog speedo that read about 4mph slower. The display also had an optional digital speed display which I always had on as it was right on the money. I asked ford about this and they said there was nothing that can be done about the analog speedometer as it was within spec.

Looks analog, but it is actually digital as a digital readout is. They just use a needle instead of an led/lcd for the display.

 

[molsonmatt]

Looks analog, but it is actually digital as a digital readout is. They just use a needle instead of an led/lcd for the display.

Yes i understand that. Just pointing out that there was a discrepancy with how it was displaying the speed and Fords response to it. There was even a difference between the two displays in the same cluster. You’d think they could dial it in and display more accurately but no dice.

 

[RLXXI]

Yes i understand that. Just pointing out that there was a discrepancy with how it was displaying the speed and Fords response to it. There was even a difference between the two displays in the same cluster. You’d think they could dial it in and display more accurately but no dice.

You only get the super accurate speedo with a police calibration. Doesn't seem fair I know.

 

[mr.Magoo]

This must be grounds for a class action !!!???
I mean, if its high they're making you a safety hazard and if it's low they're knowingly making you break the law, not to mention the loss of resale value when my truck with 300,000 miles on it actually only have 295,500 miles.

 

[Firn]

So while on bluecruise on my local highway, I noticed my speedo is off by 1 MPH. I noticed this while I was on Google Maps and its little MPH indicator while in active navigation.

This was also tested on my wife’s Equinox EV and it seems to be right on target.

How can I fix it or is due to me having nearly 37K on the ODO and need a new set of tires?

The new tires will likely fix it.

 

[pirate4x4lance]

My truck is 1 mph off as well.

 

[Madams5440]

So while on bluecruise on my local highway, I noticed my speedo is off by 1 MPH. I noticed this while I was on Google Maps and its little MPH indicator while in active navigation.

This was also tested on my wife’s Equinox EV and it seems to be right on target.

How can I fix it or is due to me having nearly 37K on the ODO and need a new set of tires?

Of all the problems I've seen, this is at the bottom of the list...

 

[tls]

This can be adjusted with Forscan. The calculated values from the common formula for rolling circumference seem to result in a displayed speed that is off by about 1MPH at 60MPH and by trial and error I have concluded that a roughly 60mm correction to the stored value fixes this even though the math doesn't quite line up that way. I would guess internally there is some rounding or other normalization of the value and it's necessary to bump it up or down past some increment.

If you decide to go this route, which will require a moderately expensive cable and a Forscan license, reach out by DM and I can walk you through the steps - you can find them all with Google but it can get a little confusing as Forscan *and* the vehicle are now a bit different from when most of the instructions you will find were written.

 

[Rayden]

I knew that motorcycles typically read +5mph and in fact, there's a thing called a speedohealer to fix that. I can't believe it's an acceptable situation with up to +/- 7mph!

 

[davehu]

So while on bluecruise on my local highway, I noticed my speedo is off by 1 MPH. I noticed this while I was on Google Maps and its little MPH indicator while in active navigation.

This was also tested on my wife’s Equinox EV and it seems to be right on target.

How can I fix it or is due to me having nearly 37K on the ODO and need a new set of tires?

OMG, 1 mph off! how can you sleep at night?

 

[chriserx]

If I'm not mistaken the Comma option that shows the 'actual' speed uses the wheel speed sensor. If accurate that would mean that the truck does know the actual speed but just displays 1 over with intent. Since you are commanding an upper bound, perhaps this is to give the software a buffer. ¯\_(ツ)_/¯

Sponsored