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Thread: Speedo giving incorrect reading

  1. #1
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    Default Speedo giving incorrect reading

    G'day Crew,
    Has anyone else had dramas with the speedo onthier MPS 3 reading out?
    I have estimated that mine is out by over 10%, and it took me quite a few months to actually realise this - I just thought everyone was speeding around me!!
    I have since read an article with regards to this problem, so I contacted Mazda to see what they would do about it. Apparently being out by 10-15% is accepatable by thier standards!!!
    I plan on discussing it with my local service centre when she goes back in to have the wheel alignment done (again), and see what they say there.
    Anyone have any information or help on this one, I imagine it would have to be something to do with electronics and such...?
    Will keep you posted on this one.
    Cheers,
    Dean

  2. #2

    Default

    I believe 10% is the generally accepted limit most manufacturers go by. Don't forget that a few millimeters in the size of your tyres (difference between new and worn) will make a few km difference at high speeds.

  3. #3
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    Default

    Tyres will effect it to - i'm running 225/40 rather than 215/45.

    Speedo say 66ks, GPS says 60Ks....made me look like a liberty driver (grandpa)!

  4. #4
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    Yeah it's annoying - but I put up with it. I'm used to it now - so when I look at my speedo and it says 70km/h, I see 60km/h

  5. #5
    dOttY Guest

    Default

    Hmm interesting. I am expecting a nice lil pic of my car cruising down the highway, very soon. If my speedo is out, thanks to the manufacturers, surely I can use that as an excuse NOT to pay my fine?? *acts more innocent than usual!* Can't I just mark it "Refer to Mazda Australia"? Lol...

  6. #6
    Nevermind Guest

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    Its usually the other way around Dotty
    You think your doing 100km/h, where your actually doing 90km/h

    so if you do get caught, you can write a thankyou letter to mazda for getting a lesser fine then you thought you would have

  7. #7
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    I find the error is at about 7% fitted with 225/45 so it would be about 8% with the stock 215/45.

    If it is actually over 10% then Mazda have to do something about it because the vehicle is no longer roadworthy with that high a speedo error. I believe 10% is RTA limit.

    15% might be verbally OK according to some mazda nobody on the phone, but is definately not OK by RTA authorities, and if they've suggested 15% is OK, they are just palming you off rather than addressing your concern.

    I've considered asking them to recalibrate mine, but never followed up on it...I doubt your speedo error is over 10%. I would bet on it being around 8%.

  8. #8
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    Default

    The MPS3 Speedo is out by ~10% when on 215/45 R18 tyres. Putting 225/45 R18 tyres on will take that back down to ~8%, but it's roughly the same on every car. I think the problem itself is in the instrument cluster, as my ScanGuage II gives the correct speed readout. Makes you wonder how many km your car has really done though... 10% out puts my car at 70,000 not 77,000km.

  9. #9
    Nevermind Guest

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    Mines not too far off comparing it to the GPS. much less then 5% difference.

  10. #10
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    Quote Originally Posted by Jeev View Post
    The MPS3 Speedo is out by ~10% when on 215/45 R18 tyres. Putting 225/45 R18 tyres on will take that back down to ~8%, but it's roughly the same on every car. I think the problem itself is in the instrument cluster, as my ScanGuage II gives the correct speed readout. Makes you wonder how many km your car has really done though... 10% out puts my car at 70,000 not 77,000km.
    last time I did a speedo check with the stock tyres on and the odometer was accurate to within 5m over 5Km, so the odometer is probably right...but having said that the very first time I did a speedo check the odo was out around 300-400m over 5Km. I think they changed something with the infamous first flash.

  11. #11
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    Quote Originally Posted by Nevermind View Post
    Mines not too far off comparing it to the GPS. much less then 5% difference.
    Wow. That's......unexpected

  12. #12
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    when the speedo says 100 my gps says 90 which one do i belive......
    Last edited by plop; 08-12-2008 at 09:40 PM.

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    Quote Originally Posted by mpsplop View Post
    when the speedo says 100 my gps says 90 which one do i belive......
    The gps

  14. #14

    Default

    Quote Originally Posted by mpsplop View Post
    when the speedo says 100 my gps says 90 which one do i belive......

    Happy Motoring
    duglet

  15. #15
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    Quote Originally Posted by Nexus View Post
    The gps
    SO I CAN TELL THE COPS "BUT THE GPS SAID I WAS ONLY DOING 110" WHEN THEY TRY TO PING ME FOR 125

  16. #16
    Nevermind Guest

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    except your only doing 110

  17. #17
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    Default

    Would love to test it against a radar for peace of mined

  18. #18
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    Quote Originally Posted by mpsplop View Post
    SO I CAN TELL THE COPS "BUT THE GPS SAID I WAS ONLY DOING 110" WHEN THEY TRY TO PING ME FOR 125
    dO THAT AND they could CONFISCATE THE gps AND inspect the logs.
    Last edited by Nexus; 08-12-2008 at 10:54 PM.

  19. #19

    Default

    Well, I can only speak for my CX7.....

    The dashhawk reads 4kmh slower than the Speedo.

    When I sit in flowing traffic ( it does that in MELBOURNE..!!! ) I constantly see this 4kmh difference.

  20. #20
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    Quote Originally Posted by Nexus View Post
    dO THAT AND they could CONFISCATE THE gps AND inspect the logs.
    Wouldn't want them to do that to me! My GPS proudly displays a top speed of 217km/h

    (on a private road ofcourse)
    2014 Mk7 Golf R | DSG | Reflex Silver | Leather | Drive Assist | Bi-Xenon Headlights
    1981 Lincoln Town Car | Auto | 80s Cream | 90s brown interior | 5.0L V8 | Currently no working headlights



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