Odometer OVER-measuring mileage--help! | FerrariChat
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Odometer OVER-measuring mileage--help!

Discussion in 'Technical Q&A' started by 348SStb, Oct 27, 2004.

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  1. 348SStb

    348SStb F1 Rookie
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    #1 348SStb, Oct 27, 2004
    For every 10 real miles I drive, my odometer says that I've gone about 11 miles. That is, the odometer is over-measuring the actual distance that thecar has traveled.

    I noticed when I bought the car that the odometer was measuring some "short" miles!

    I tested my odometer against other cars and confirmed that it was a little inaccurate. I wrote some numbers down that showed that the inaccuracy of the odometer varies with vehicle speed.

    Is there any way to fix the odometer? I AM LOSING MILEAGE! The car says it's traveled 16,140 miles, but I suppose it's over a thousand less than that. I've been told ya just can't do anything about it. I'm losing money here folks!

    Oh yea, and my speedometer is exactly 6 M.P.H. fast. That is, if it says I'm going 60, I'm really going 54 miles per hour.
     
  2. Oengus

    Oengus F1 World Champ
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    #2 Oengus, Oct 27, 2004
    I like the thought of going 71 in a 65 and not really doing it!!
     
  3. coolblue

    coolblue Karting

    May 6, 2004
    217
    #3 coolblue, Oct 27, 2004
    Does this mean that when you are standing still you are moving at six miles an hour? This is freaking me out.............
     
  4. TOM B

    TOM B Formula 3

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    #4 TOM B, Oct 27, 2004
    Dave,
    Just a hunch, but do you have the stock size tires for the car or have they been changed. This can make a difference in odometer and speedometer accuracy.
     
  5. ethans_dad

    ethans_dad Formula Junior

    Mar 24, 2002
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    Stephen R Chong
    #5 ethans_dad, Oct 27, 2004
    Actually, at rest, your speedo probably pegs at 10MPH. This is typical of most Ferraris. Have you checked the sender unit? As far as the calibration of your odometer, your best solution is to have it reset by a gauge specialist like Palo Alto Speedos. They can check and recalibrate it. My odo is out also, but I'm keeping and driving my car so I don't worry about it. If resale is a big concern, I'd definitly have it fixed and then adjusted with DMV so you don't get a red flag on your VIN.

    Pretty typical stuff for Ferraris unfortunately...
     
  6. 348SStb

    348SStb F1 Rookie
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    #6 348SStb, Oct 27, 2004
    Running factory wheels and factory specified tires...

    I've heard of that company in Palo Alto... the process seems pretty complicated though... How can I get this stuff fixed without sending the damned car over to them? I'm in NY, they're in CA!

    Haven't noticed that my speedometer reads above zero at rest...
     
  7. don_xvi

    don_xvi F1 Rookie

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    #7 don_xvi, Oct 28, 2004
    I assume that you mean the number of MPH it's off by varies with speed, and it's a constant 10%?

    Can you or someone clarify how the 348 drives the speedo? Is it still mechanical or electronical? ;) It's gotta come down to 1 of two problems: input our output! I'm going to guess that a car of that vintage would have a conventional speedo cable. So you have to think about everything from the tires (which you've stated are stock) back up the driveline to the speedo sender unit first. Were there any alternative rear end ratios available on a 348? Not sure exactly where the 348 picks up the speed at. Does it use a little set of gears to drive the cable like good ol' 'Murrican cars do? They could be incorrect. Then finally, it's true, the odo drive in the speedo COULD be wrong, but this isn't exactly something that's "out of adjustment" it would have to be misbuilt (or re-built).
    If it's electronically driven, you probably still have to worry about the rear gear ratio, the number of teeth on whatever ring it's picking up the signal on, and then Lord only knows what could be wrong in the speedo head at that point!
     
  8. TOM B

    TOM B Formula 3

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    #8 TOM B, Oct 28, 2004

    If it's determined that the speedometer and odometer are at fault, i'd call Palo Alto and see if they have a fix for this problem. If so, you'll have to send them both gauges.Turnaround on my tachometer was only 1 day.
     
  9. 348SStb

    348SStb F1 Rookie
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    #9 348SStb, Oct 28, 2004
    The speedometer is electronic, but the odometer is mechanical.

    The speedometer ALWAYS measures exactly 6 miles per hour fast; the erroneous speed measurement does not vary with changing speed.
     
  10. Merdav

    Merdav Formula Junior

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    #10 Merdav, Oct 28, 2004
    In the future, when cars can go the speed of light, will the headlights work....?
     
  11. 348SStb

    348SStb F1 Rookie
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    #11 348SStb, Oct 28, 2004
    hahahahaha lol :D
     
  12. vpi_astro

    vpi_astro Rookie

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    #12 vpi_astro, Oct 28, 2004
    My 2002 Maserati Spyder Cambiocorsa also displays an indicated speed on the speedometer of 6 mph greater than the speed I measure with a handheld GPS receiver. I checked it against two different brands of GPS receiver with the same result. My dealer checked and confirmed this as well but suggested no fix. I've not checked odometer accuracy but assume its driven from the same sensor?
     
  13. fmomen

    fmomen Karting

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    #13 fmomen, Oct 29, 2004
    i have a used 348(2.7) speedometer with me which is fine. The reason I changed mine was because the car is in a KMph country and therefore!!. Should you need to change yours, let me know. The reading on mine is approx. 12k
     
  14. TOM B

    TOM B Formula 3

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    #14 TOM B, Oct 29, 2004

    Good question. But the one that should be answered first is......at the speed of sound..will you haer the radio? :)
     
  15. Ricambi America

    Ricambi America F1 World Champ
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    #15 Ricambi America, Oct 29, 2004
    Yes, you will hear the sound. Fighter pilots get radio transmissions, don't they?


    "baby einstein"
    -d
     
  16. coolblue

    coolblue Karting

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    #16 coolblue, Oct 29, 2004
     
  17. Ricambi America

    Ricambi America F1 World Champ
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    #17 Ricambi America, Oct 29, 2004
    I meant within the cockpit, they hear sound. :) How did we get on this topic???
     
  18. TOM B

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    #18 TOM B, Oct 29, 2004

    Michael355 started it. Blame him. :)
     
  19. Lloyd

    Lloyd F1 Rookie

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    #19 Lloyd, Oct 29, 2004
    What do you expect from Vague-lia guages? :)
     
  20. ferrarifixer

    ferrarifixer F1 Veteran
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    #20 ferrarifixer, Oct 30, 2004
    Ok, to be serious for a moment, your speedo is fed by an electronic sender that gets pulses from a drive within the gearbox.

    The odometer is fed from within the speedo head, so is the same error as the speed reading.

    Check your tyre size and pressure. If you are not using the correct rolling circumference, or even if your pressures are very low, your speed and mileage can vary by surprising amounts.

    As a side note...the mileage on 288 and F40 is NEVER to be assumed correct without history to back it up...the sender unit jumps out at you when you open the back or look underneath and seems to always be very clean...like it gets fiddled with a lot....
     
  21. 348SStb

    348SStb F1 Rookie
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    #21 348SStb, Oct 30, 2004
    Thanks Phil.

    As I said, my tire sizes are absolutely correct. The pressures are also correct.

    I actually heard that the speedometer is electric and that the odometer is mechanical--that they're two separate entities...
     
  22. TOM B

    TOM B Formula 3

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    #22 TOM B, Oct 30, 2004


    Dave,
    I don't know the 348 specifically, but my 3.2 Mondial's odometer is electric. Frankly, I don't see how (or why) a cable would be run all the way from the dashboard to the engine compartment. So I doubt it's mechanical.
    Interesting side note.....my odometer takes its signal from the trip odometer. My trip odometer would get stuck at times and at those times, the main odometer wouldn't register miles. I disassembled and used some WD-40. Everything is fine now.
     

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