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Flakey Nav Distance

Discussion in 'Gen 2 Prius Audio and Electronics' started by dhancock, Jul 31, 2007.

  1. dhancock

    dhancock 2 Prius Family

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    Has anyone observed this problem?

    Recently we drove from the Atlanta area to Maryland (we are there right now) and while under way (on Interstates) we noticed that the distance to our destination was somewhat erratic. Meaning - that while on the same Interstate (I-85 North) the distance to our destination would, at times INCREASE! The distance to our next turn and estimated arrival time would also change accordingly. The change was on the order of 40-50 miles.

    We did not like any of the route choices that the system had given us (it wanted us to go I-95, real bad news going through Richmond and DC in late afternoon) so we forced an intermediate point on I-81 in Virginia. Other than the screwy distance readings, the Nav system worked fine.

    Is this a fluke? Or is it normal? If it is normal, does anyone have any idea as to why? Or does it indicate somethng wrong (like a bad memory)? If that, how do I deal with the dealer? (Had the car 2 months).
     
    #1 dhancock, Jul 31, 2007
  2. Vagabond

    Vagabond Active Member

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    Check your manual on calibration

    But other than that, that's really odd.
     
    #2 Vagabond, Jul 31, 2007
  3. qbee42

    qbee42 My other car is a boat

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    There are some locations where the map database is goofy; yours may be one of them. See how it does on other trips.

    Tom
     
    #3 qbee42, Jul 31, 2007
  4. dhancock

    dhancock 2 Prius Family

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    <div class='quotetop'>QUOTE(qbee42 @ Jul 31 2007, 04:58 PM) [snapback]488287[/snapback]</div>
    We've been on other trips (including Rochester to Atlanta) and haven't seen this before. The map database theory seems to make sense.

    Anyone else?
     
    #4 dhancock, Jul 31, 2007
  5. skandale

    skandale Member

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    I would subscribe to the database theory.

    Only other reason I can think of must be that you chose to make road than the NAVI suggested. A recalculation to fit the new road choice. That could result in a longer trip.


    Stein
     
    #5 skandale, Aug 1, 2007
  6. dhancock

    dhancock 2 Prius Family

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    <div class='quotetop'>QUOTE(skanDALE @ Aug 1 2007, 03:33 AM) [snapback]488533[/snapback]</div>
    I don't think that (different route) is it, because I changed the routing by inserting a mid-point destination and it was on the way to that mid-point that I had the problem.

    Is there some place I can get more info on the database issue that gbee2 mentions? I had the problem on a pretty common (I-85 between Atlanta and Charlotte) route.
     
    #6 dhancock, Aug 1, 2007
  7. Marvinh

    Marvinh Marvin

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    <div class='quotetop'>QUOTE(dhancock @ Jul 31 2007, 01:39 PM) [snapback]488151[/snapback]</div>
    I can respond regarding the difference in arrival time (and possibly it would affect the mileage variance as well)...the system takes into account your vehicle speed and adjusts accordingly. You can see this if you are stuck in traffic. The minutes to destination will not change as quickly as when you are moving.

    Hope this helps - Marvin
     
    #7 Marvinh, Aug 2, 2007
  8. slair

    slair Ubër Senior Member

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    ^^ I was going to say what he said. The GPS does account for vehicle speed. I noticed this when I took a 600 mile trip. I went through different states with different speed limits. Indiana is 75, but Kentucky was only 65. Once I slowed down in KY, the GPS did increase my ETA because of my speed decrease.
     
    #8 slair, Aug 2, 2007
  9. qbee42

    qbee42 My other car is a boat

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    <div class='quotetop'>QUOTE(Marvinh @ Aug 2 2007, 10:58 AM) [snapback]489248[/snapback]</div>
    This makes no difference with mileage. The mileage is computed from the route, and it's the same whether you drive 5 or 50 mph. Route settings will cause a mileage change, but not speed or speed settings.

    Tom
     
    #9 qbee42, Aug 2, 2007
  10. dhancock

    dhancock 2 Prius Family

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    It was the sudden changes in distance to destination that I was concerned about. The time to arrival also changed - but that was a result of the distance change.

    BTW: The part of the route that I noticed this on was common with both the original NAV route and the revised route. Now, perhaps the calculations were flipping back and forth between the two routes - but I believe that the milage change was greater than the difference between the two routes.

    Thanks for all the comments & suggestions on this.
     
    #10 dhancock, Aug 2, 2007
  11. KTPhil

    KTPhil Active Member

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    The Nav system uses stored speed assumptions for each road type. It does not adjust your ETAs based on your actual speeds. You can change those assumed speeds in the setup menu, but once set, they are fixed. This is true for the '04-'06 systems, anyway.
     
    #11 KTPhil, Aug 9, 2007
  12. dhancock

    dhancock 2 Prius Family

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    <div class='quotetop'>QUOTE(KTPhil @ Aug 9 2007, 01:06 AM) [snapback]492861[/snapback]</div>
    Yes, but my issue was with the distance to arrival changing (the ETAs changed with the distance).

    BTW: I assume that the stored speed assumptios used are the ones that I set.
     
    #12 dhancock, Aug 9, 2007
  13. telstar

    telstar New Member

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    One item I recall reading in the manual is that while in route you make a change for a side trip the mileage will be calculated as the crow flies rather than actual street mileage. I have no idea why this happens but that's what the manual (07) said :huh:
     
    #13 telstar, Aug 15, 2007
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