The speedometer reads higher then waze gps app?

Discussion in 'Mustang S550 General Forums' started by jrsimon27, Feb 2, 2020.

  1. jrsimon27

    jrsimon27 Well-Known Member

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    Hi friends using the waze app i see that the speed shown in the app reads like 3mph lower then the speedometer in the dash is this normal?
    Thanks.
     
  2. michaelchatten

    michaelchatten Well-Known Member

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    Mine reads about 5 mph higher in Waze than the speedometer.
     
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  3. Cory S

    Cory S Well-Known Member

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    Not uncommon. Most all speedometers are set to read 2-4mph higher than actual speed at 60-80mph. It gets exponentially worse after that.
     
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  4. samd1351

    samd1351 Well-Known Member

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    I'd trust the factory speedometer over the waze app. The gps in your phone, which is what waze is using to calculate your mph, is not as accurate as the actual speedometer. Cell phone gps has an accuracy of, at best 30 meters. Trust the car.
     
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  5. Cory S

    Cory S Well-Known Member

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    The car is wrong.... All of them are. GPS accuracy in 30m is 90’. A car is traveling 88’ per SECOND at 60mph. The GPS sub net refresh rate is .50-1 second.
     
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  6. Troutwrangler

    Troutwrangler Well-Known Member

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    Hasn't happened in the Mustang yet, but the State Police verify one of my speedometers about every 2-3 years...
    Their radar always reads higher than what I think it should...
     
  7. Briebee72

    Briebee72 Well-Known Member

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    Question? Have you changed your tire at all from factory size? If you bought used have you checked that they are still factory size? Should be a sticker in driver door jam. That size is what your speedometer is set to. if you have change tire or wheel size in anyway then your speedo will be off. And it becomes more inaccurate the faster you go. If you have factory tire size on then gps on apps get your speed by an average I have set my cruise before at 60 and watched my gps app go from 58 to 63 back and forth.

    I changed my tire size and so did my buddy, both our speedos were off. We did use a dedicated gps speed app and saw how far off they were for comparison. They went in with forscan changed the values for our new wheels and tires and bingo checked against gps speed again and was dead on now.

    But at the end of the day we rely to much on tech. Gonna take what a third party map app says your speed is through a satellite over and average or the actual on the ground speedometer that was calibrated at the factory? Now if you are not running oem tire sizes well that is most likely the culprit.

    if you check sticker and you are running a different size go to this calculator and put in oem size and what you have now and it will tell you what speed you are off. https://tiresize.com/speedometer-calibration/
     
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  8. Cory S

    Cory S Well-Known Member

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    A speedometer must never read less than the actual speed or show more than 110% of actual speed + 6.25mph. So, if your true speed is 40mph, your speedometer can legally read up to 50.25mph, but never less than 40mph. In other words, if it reads 50mph, you won’t be doing more than 50mph but it’s possible you might actually only be travelling at 40mph.

    Car manufacturers will normally calibrate their speedometers to read ‘high’ by a certain amount in order to adhere to this law and ensure they never show less than true speed.
     
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  9. OP
    OP
    jrsimon27

    jrsimon27 Well-Known Member

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    Car tires are stock.
    Thanks
     
  10. SAL-E

    SAL-E Well-Known Member

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    My Garmin GPS says I am doing 74 when the speedo says 75. The exact same thing is true with the wife's Ford Edge. That's close enough for me.
     
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  11. Bullitt 2159

    Bullitt 2159 Member

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    You need to update your Sync 3 to the current Build version.
     
  12. Ecoboosted

    Ecoboosted Well-Known Member

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    I haven’t done this yet. What’s the process?
     
  13. Briebee72

    Briebee72 Well-Known Member

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    I may be wrong here but sync doesn't have anything to do with your speedometer. It the microsoft file system and data management software for the head unit.
     
  14. GT Pony

    GT Pony Well-Known Member

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    I checked my GT with a Garmin when the car and tires were new, and speedo was also only 1 MPH faster than the Garmin all the way to 100 mph. Checked it at 25, 50, 75 and 100. The Mustang is the most accurate speedo I've seen compared to other vehicles I've had.
     
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  15. Bullitt 2159

    Bullitt 2159 Member

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    #15 Bullitt 2159, Feb 3, 2020
    Last edited: Feb 3, 2020
    https://owner.ford.com/user/dashboard.html

    I think the Build 19205 shown below was before I updated mine. The update will contain a higher number and it will fix the Waze speed issue. I did it on my '18 Taurus and my '16 Mustang.
    upload_2020-2-3_8-10-24.png
     
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