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Some Hills just too steep?

Discussion in 'Gen 2 Prius Technical Discussion' started by NoMoShocks, Jun 17, 2007.

  1. NoMoShocks

    NoMoShocks Electrical Engineer

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    Has anyone come across a hill that was just too steep for their Prius?

    I was taking my son and a friend to a film party. We started up a private gravel road and the tires were spinning on a couple of rocks, but we were moving along just fine. Then we got to a steeper place and I slowed down just a little to avoid spinning the tires. All of a sudden, the car came to a complete stop and just would not go any further. It felt like I was out of gas, and the electric drive didn't have enough power. Either the feul pump didn't work at that angle, or the Vehicle Stability Control sensed that the wheels had no traction and sut down power to the wheels.

    Fortunately, the homeowner came down and showed us another route that was not so steep. He said most cars could not come up that way unless they got a good run at the hill, but I was just surpeised with the feeling of having no power to even give it a try.

    Still love the Prius though. Gave it a bath as soon as I got it home again.
     
  2. efusco

    efusco Moderator Emeritus
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    I find that it'll handle any grade just fine...but if you throw gravel, wet pavement, ice/snow into the mix you're SOL. My '04 seems to be much worse than a friend of mine's '07 on the gravel drive at my lake house even though I have "good" Michelin HydroEdges and he's still on Integrities. This is "thanks" to the traction control which is very agressive so as to protect MG1 from over spinning and breaking.

    If you can sustain your momentum on those kinds of inclines you're ok, if you stop or slow or hit a particularly loose/slippery spot you're screwed.
     
  3. ken1784

    ken1784 SuperMID designer

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    <div class='quotetop'>QUOTE(NoMoShocks @ Jun 17 2007, 06:29 PM) [snapback]463367[/snapback]</div>
    So, Prius is one of the most cars. :)

    Ken@Japan
     
  4. mbarrows

    mbarrows Illini Bird

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    <div class='quotetop'>QUOTE(efusco @ Jun 17 2007, 04:35 AM) [snapback]463368[/snapback]</div>


    Do you think Toyota will ever correct this design flaw and allow the VSC to be disengaged? :(
     
  5. qbee42

    qbee42 My other car is a boat

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    <div class='quotetop'>QUOTE(mbarrows @ Jun 17 2007, 08:04 AM) [snapback]463383[/snapback]</div>
    It's not the VSC, it's the traction control. The traction control can be disengaged, but then you run a very real chance of damaging parts of the HSD.

    Tom
     
  6. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(qbee42 @ Jun 17 2007, 07:52 AM) [snapback]463396[/snapback]</div>
    I would hope they could devise a way to simply attenuate the effect to the point that the wheels will continue to turn but at a rate that would prevent damage to MG1 rather than the dramatic complete cut-out that currently occurs with the slightest slippage.


    It would seem simple enough to have a traction control system that measured the wheel slip speed and duration and adjusted the throttle accordingly to minimize the spin.
     
  7. MarinJohn

    MarinJohn Senior Member

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    The traction control has been the bane of many posts, and I agree with Evan. It does not seem insurmountable that Toyota could attenuate the effect thereby giving owners less problems on hills, in snow, and especially on quick start merging. While most of us learn how to anticipate the 'problem' still, there are times when no amount of careful acceleration can override the problem, and this could be a matter of life and death. Certainly it is obvious that a stalled attempt to jump into oncoming traffic could be fatal. Not so obvious are the times when, like the OP, one finds oneself on a hill, stalled and being forced to back down. It's the backing down in these touchy situations where problems could easily arise, either from an uncontrolled slide backwards on gravel or in snow/ice. THis problem must be addressed and fixed on the new models. We understand the Generation 2 was an 'experimental' vehicle where problems like this are uncovered. Generation 3 had better address all such inadequacies or TOyota will fall into the GM category of ignoring consumers, and we all know where that leads.
     
  8. usbseawolf2000

    usbseawolf2000 HSD PhD

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    <div class='quotetop'>QUOTE(efusco @ Jun 17 2007, 08:55 AM) [snapback]463397[/snapback]</div>
    It seems to be doing that already. From the video I made with my 06 during last winter, the traction was maintaining the wheel slippage to under 15 mph on the speedometer.
     
  9. john1701a

    john1701a Prius Guru

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    <div class='quotetop'>QUOTE(MarinJohn @ Jun 17 2007, 11:05 AM) [snapback]463451[/snapback]</div>
    Camry-Hybrid offers an improvement already, where there is greater electric power and a secondary gearset. Its response is different. The development process hasn't concluded. The upcoming new Prius will likely offer fine-tuning to that.
     
  10. NoMoShocks

    NoMoShocks Electrical Engineer

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    Thanks for all the comments.

    Just to clarify, I am not quite so concerned about the Prius being grouped with "Most Cars" that cannot make this particular hill. I was just very surprised by the sensation as the driver that I pushed on the pedal, and it was as if I were out of gas. Nothing. I probably could have made another run and made it if I kept my speed up, but it was over taxing the mudflaps, becuase these homeowners like to include many 2 inch diameter rocks rather than straight pea gravel ar even small 1/2 river rock on their private road.

    I was happy the homeowner came down and pointed me to the other road. I had actually seen the other road, but it looked far less traveled to make me believe the steep one was the main one.
     
  11. derh2o

    derh2o Junior Member

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    i have experienced a similar problem. on a dry, steep hill, i can't get the car to move very much, regardless of how much throttle i give it. any idea's? I have an '07 touring model.
     
  12. ceric

    ceric New Member

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    If not too long a hill, you might want to try backing up the hill. This effectively change Prius into a rear-wheel drive... It is on pure-electric in R mode, and RWD gives you more normal force on the driving wheels.
     
  13. dwreed3rd

    dwreed3rd New Member

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    Ditto to Cereic; Any front rear drive will have much better traction backing up a steep hill. Going up a steep hill forward shifts much of the weight to the rear wheels. Backing up keeps it on the drive wheels where you want it.
    P.S. Please! This technique is only for off-road or back/dirt road conditions.
     
  14. tochatihu

    tochatihu Senior Member

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    Here's yer steep road list:

    http://www.geographylists.com/list17y.html

    I have Prius-ed up one of those 32% grades and it works OK. To bicycle up Fargo Street requires all but the fittest to 'tack' from edge to edge. It is an annual contest for the LA Wheelmen.

    There are steep unpaved roads that Prius must attack very slowly for other reasons. This puts the drivetrain in a very inefficient condition, and can actually bring the Prius to tears. The moderately insane can drive to the Mahogany Flats campground in Death Valley and see what I mean.

    Besides those fixes already mentioned, a computer-braked vehicle such as Prius could be programmed* to slow the slipping wheel by friction, while continuing to apply power.

    *Theoretically, I mean.

    DAS
     
  15. David Beale

    David Beale Senior Member

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    Backing up a "too steep" hill is not an option. You WILL run out of power. The Prius is "gutless" in reverse, due to current limiting to protect the battery, among other things. I almost got stuck in loose wood chips on level mud when I tried to back up when turning around. The car would barely move, and the wheels were not traction limited. I just didn't have enough power to move at more than a crawl.

    The traction control thing is not a failure or fault. It's there to protect the cars' mechanicals. Unless you really want to spend several thousands to repair damage you caused by spinning the wheels?

    Standard off-road driving techniques (momentum maintenance etc) will get you up most hills unless the surface is just too rough. Prius is NOT an off-road vehicle. Get a Highlander hybrid if you want that, though even it is limited in what it can do compared to "gas guzzlers".
     
  16. dwreed3rd

    dwreed3rd New Member

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    Thanks that's good to know, bad news, but good to know. We lived up at the end of a dirt lane in PA,
    The last 200 yrds was really steep and in the winter was a problem sometimes even for rear wheeled vehicles. If we still lived there I guess we would have to forego the Prius. Not a problem here in GA but we do go back for visits. Guess we'll have to park the Prius in the garage and take the Avalon. :sick: Not that we don't love our Avalon, it's obviously around 1/2 the mpg. Gee! I'd better check, our driveway, here in GA. It is really steep and well over a hundred feet almost 200. I need to check the slope. Not alot of room to turn around in the driveway and don't like the thought of backing down and into the garage. Can do it but it's tight. :sick::sick:
     
  17. mingoglia

    mingoglia Member

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    I backed up a pretty steep driveway once and it seemed to have enough power. Granted, it's certainly limited, but it feels more like it gently feeds the power in and that if it was steeper I'm confident it would have still gone up. It felt like it was probably 25-28% grade but I have very little frame of reference so that's a guess at best.

    I did play on some residential hills this past weekend in San Diego that appeared to be at least as steep as anything I ever went up in San Francisco. My wife was at the hotel putting the kids down for bed while my mission was to go out and buy some sun block. Since I wasn't ready for bed myself I decided to take about an hour detour checking out some homes... I don't have very many very steep grades where I'm from I probably looked like a moron stopping and going up and down the hill to see how the Prius did. I spent at least 30 minutes driving around trying to find the steepest hills I could find. :biggrin1: Anyway, the Prius did fine... but once again all I can say is I believe the steepest ones I found were at least as steep as the steepest hills I've driven/walked on in San Fran but I could be mistaken.... only been to San Fran 3 times, the most recent being about 2 years ago.

    Mike
     
  18. dwreed3rd

    dwreed3rd New Member

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    Thanks Mike, that's reasurring. Does that include Lombard St?
     
  19. combsad7

    combsad7 Junior Member

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    On our family farm there is a hill with an old dirt road that my Prius can't climb. It is a very steep hill with about 55% grade between the trees. I think the road was a forest road.
     
  20. Rokeby

    Rokeby Member

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    OK, I'm getting very confused and concerned as to what to expect when the
    going gets a little slippery; in this I include snow/ice, wet grass/leaves,
    sand/gravel on the road, steep gravel road/driveway.

    I have read threads that variously say that the Prius will grind its way out,
    and others that emphatically say that the Prius totally shuts down. So which
    is it?

    Here are two threads that say the Prius just sat there, unmoving, paralyzed,
    whimpering pathetically:

    http://priuschat.com/forums/prius-main-forum/27564-i-got-stuck-mud-4.html

    http://priuschat.com/forums/prius-main-forum/27739-i-hate-my-prius-9.html

    Here is my thread reporting that I found that my 2008 did move on a slick
    icy road:

    http://priuschat.com/forums/prius-technical-discussion/42846-traction-control-worked-i-think.html

    There is another thread -- that I can't find --wherein a poster reported being
    able to back out of a front wheel in a wet grassy ditch situation. (Help me
    here, maybe you can find It.)

    This Will-It-Go-or-Won't-It-Go? uncertainty just makes me crazy.

    What am I to expect when, not if, I find myself in one of these situations?