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Surging motor RPM at 50mph

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Opiesbro, Jan 7, 2015.

  1. Opiesbro

    Opiesbro Junior Member

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    About a week ago I noticed my 2012 II felt more noticeable when the electric motor would assist. I thought it was temperature related as it got really cold here in MO. But tonight on my way home I had the cruise set at 50mph and I had the same issue. This time I changed the monitor screen to see when the electric motor was kicking in. However the electric motor was not helping and it felt like the RPMs were surging up and down radically and for no reason. My car is still under warranty but I can not make it do it on command so I fear the dealership will not find it. Any suggestions?

    Thanks,
     
    #1 Opiesbro, Jan 7, 2015
  2. bisco

    bisco cookie crumbler

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    was it hilly?
     
    #2 bisco, Jan 7, 2015
  3. Opiesbro

    Opiesbro Junior Member

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    No. It was on a flat 4 lane road. I drive it everyday and do the same condition everyday. It has never happened in this spot before. :(
     
    #3 Opiesbro, Jan 7, 2015
  4. bisco

    bisco cookie crumbler

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    unless it throws a code, they will not do anything. does it do it with the cc off?
     
    #4 bisco, Jan 7, 2015
  5. Opiesbro

    Opiesbro Junior Member

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    I'm going to try that next occurrence. The only thing that I have changed lately is I took the hub caps off and don't have center caps on the wheels yet.
     
    #5 Opiesbro, Jan 7, 2015
  6. bisco

    bisco cookie crumbler

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    that shouldn't effect it. check you engine oil level.
     
    #6 bisco, Jan 7, 2015
  7. Opiesbro

    Opiesbro Junior Member

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    It is ready for an oil change. The Maintenance Required indicator is on.
     
    #7 Opiesbro, Jan 7, 2015
  8. bisco

    bisco cookie crumbler

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    until you take it in, check the level to make sure it's not part of the problem.
     
    #8 bisco, Jan 7, 2015
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    How many miles on the odometer? I'm thinking of exhaust gas recirculation circuit, and it's tendency to clog. Just a stab.
     
    #9 Mendel Leisk, Jan 7, 2015
  10. Opiesbro

    Opiesbro Junior Member

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    It has about 31,000 miles on the odometer. I drive about 4,300 miles a month so I want to get it taken care of soon.
     
    #10 Opiesbro, Jan 7, 2015
  11. FuelMiser

    FuelMiser Senior Member

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    I pay attention to the state of charge (SOC) and expect to hear the internal combustion engine (ICE) contribute more when the SOC is low. This results in more noticeable engine sound than when both are contributing. You already said your electric motor was not contributing, so engine noise is expected. You say you had cruise control engaged, so it was modulating the engine speed to maintain road speed. I would not worry about it, unless you get surging when you are accelerating. Does the engine accelerate smoothly?
     
    #11 FuelMiser, Jan 8, 2015
  12. Opiesbro

    Opiesbro Junior Member

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    It does appear to accelerate smoothly. The battery was 2 bars from full at the time and it was like the car was giving it lots of gas then no gas without a smooth transition. This morning I checked the oil and it was above the full mark just a tad and the car seemed fine for my 75mile commute.
     
    #12 Opiesbro, Jan 8, 2015
  13. FuelMiser

    FuelMiser Senior Member

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    In that case, I'd chalk it up to cruise control oscillation--over-controlling the throttle to maintain the speed. Sounds like your engine is fine.
     
    #13 FuelMiser, Jan 8, 2015
  14. guppy

    guppy Junior Member

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    Did you ever find the cause of this? I had exactly the same thing happen on the way home tonight. It's pretty cold (around -20 celcius) and I was crusing long at around 100kph and felt the car "surging" forward. I was not using cruise control. You could actually see it visibly on the fuel consumption guage - it was going up and down from around 4-7 l/100km like a yo-yo!

    I floored the accelerator for a second and let it drop back down and it stopped doing it. No idea what the cause could be.
     
    #14 guppy, Feb 2, 2015
  15. hippy

    hippy New Member

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    Having same problem. Our is gen 2 and if g put my foot down heavy up hills the engine revs like crazy but the electric motor does nothing. The battery shows as full and it does work sometimes and on EV?
    Our is high milage but has been well looked after.
     
    #15 hippy, Mar 5, 2015
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