Prius losses power when ascending to high elevation

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by mcgw1000, Mar 25, 2017.

  1. mcgw1000

    mcgw1000 New Member

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    Visited Mauna Kea Obeservation Point on the island of Hawaii recently. The elevation up at the telescopes is 13,700 ft. While ascending the mountain the engine lost a great deal of power climbing from 9,000 ft to 12,000 ft. There is a parking area at 12,000 ft where we stopped to acclimate to the high elevation. When we started the car and continued up the mountain the car was back to normal power. Was this the Prius computer resetting to the atmospheric pressure when re-started at the parking area?
     
    #1 mcgw1000, Mar 25, 2017
  2. Sam Spade

    Sam Spade Senior Member

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    Maybe. But that kind of elevation change WILL cause a loss of power in all kinds of gas engines, some more than others.
    Most can't fully compensate for the thinner air.

    Is it possible that you drove that second leg slower than the first ??
     
    #2 Sam Spade, Mar 25, 2017
  3. mcgw1000

    mcgw1000 New Member

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    No change in speed or grade. I know earlier versions of ECM's using MAP used a sample of atmospheric pressure when first started and only updated it when the throtle was completely opened or the engine was turned off then back on. Was curious if that it what was experienced.
     
    #3 mcgw1000, Mar 25, 2017
  4. Aaron Vitolins

    Aaron Vitolins Senior Member

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    What was the hybrid battery level at when it lost power?
     
    #4 Aaron Vitolins, Mar 25, 2017
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  5. drysider

    drysider Active Member

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    This sounds like perhaps water in the gas. Stopping would melt any ice that had formed and off you would go.
     
    #5 drysider, Mar 25, 2017
  6. mcgw1000

    mcgw1000 New Member

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    It was low around 2 bars. It also stayed low after starting back up. Charged up on the way down the mountain.
     
    #6 mcgw1000, Mar 26, 2017
  7. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Maybe when it hit two bars is when you lost power? At two bars the hybrid system takes a fair bit of the engine power to recharge the hybrid battery. Just a thought
     
    #7 Aaron Vitolins, Mar 27, 2017
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    I'm thinking borderline hybrid battery, and symptoms starting to manifest due to extreme load of sustained hill climb. How many miles on it?
     
    #8 Mendel Leisk, Mar 27, 2017
  9. kc410

    kc410 Active Member

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    The Prius electronics _will_ protect the 201V main battery at _all_ costs. It sounds that going up the mountain the main battery got down to two bars. The Prius will then try & charge the battery. But now the gas engine has to provide propulsion to the vehicle AND supply a 2-4KW charge to the main battery - The Prius _will_ charge the main battery (remember it is programmed to protect the main battery at all costs) - this would result in a large loss in power available for propulsion up the mountain.

    Once you took a break at 12,000ft the Prius had a chance to recharge the main battery quickly. When you took off again the Prius could use all of the gas engine power to push the Prius uphill.
     
    #9 kc410, Mar 27, 2017
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    I think OP shut the car down in that parking lot? (n)
     
    #10 Mendel Leisk, Mar 27, 2017
  11. jerrymildred

    jerrymildred Senior Member

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    I like kc410's theory. Just for the fun of it, I went to Wallace Racing - Braking HP Loss at Altitude Calculator and entered 12,000 feet for the elevation and 134 hp. It calculated a loss of 48.24 bhp. Of course, the electric motor part doesn't lose power at elevation, but if it's working hard and long, I would thing that the system should reduce power to protect the battery and mg from overheating. Let it cool down in the parking lot and charge a bit in the lot, too, as you make your way back to the road and that should help it bounce back quite a bit.

    Maybe some of you friends in Colorado can let us know how yours do on Mt. Evans or Pikes Peak.
     
    #11 jerrymildred, Mar 27, 2017
    Last edited: Mar 27, 2017
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