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2017 Prius - Gen 4 acceleration issues - type two

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Priusdude3, Jun 19, 2021.

  1. Priusdude3

    Priusdude3 New Member

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    Started my Prius today and was about to run some errands, when I backed out it seemed fine but when I put it into drive the engine revved up and it hesitated for a second or two like the transmission was slipping I drove around my neighborhood and to my parents (got on the highway) to test it, it was inconsistent did not happen every time but it would only happen when I was at a full stop and then started and once it was in gear it acted fine and I made it a point to not totally stop, I read somewhere that it could be the computer in it acting up, but I still want to change my transmission fluid I’m at 73K and it hasn’t been done before, it was pretty warm today (94°F) but was warmer yesterday and didn’t act up, any input or advice would be greatly appreciated.
     
  2. bisco

    bisco cookie crumbler

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    make sure the hybrid battery vent is open and the filter clean. might be worth checkin/cleaning the blower.
    was it parked in the sun?
     
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  3. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    Although not mentioned there is a filter behind that vent too.
     
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  4. davecook89t

    davecook89t Senior Member

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    A Prius does not have a torque converter or gears like a traditional auto transmission does, so it cannot "slip". Of course, problems can arise in the drive train that make it seem like that is happening, but probably they cannot be rectified by changing the transmission fluid. There is no harm in changing the transmission fluid, and some owners believe it should be done regularly, but Toyota does not require it as they consider it a "lifetime" fluid.

    Did you happen to notice your HV battery's State of Charge as displayed on the MFD when the event you described was occurring? If it was at a very low level, that could explain the revving of the engine and the car's overall sluggishness.

    In any event, the HV components of your car are still under warranty, so if this issue becomes serious enough that an error message or lights are displayed on your dash, you should be able to take the car into a dealer and have it analyzed and, if necessary, repaired free of charge.
     
  5. ChapmanF

    ChapmanF Senior Member

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    Another thing that can happen: right after starting, the Prius computer likes to baby the engine, and use mostly battery power to get you going down the road, with the engine more or less idling. As the engine warms up, the computer gradually puts it more and more into the mix; usually you don't notice that. That's why there's generally no need to wait around "warming up the engine" before driving, as people used to do; the computer is taking care of that, even while you're already moving down the road.

    But if you're driving along in that early stage and you happen to press a little harder on the go pedal than the available battery power can cover, then the computer says "ok, so much for babying, gonna need engine for that" and the engine will kind of abruptly rev higher to give you the additional power. If you're not used to a Prius, that can feel/sound like "slipping", but it's perfectly normal.
     
  6. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    You are assuming it is not a high mileage vehicle. If there are too many miles on it it is out of HV warranty.
     
  7. davecook89t

    davecook89t Senior Member

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  8. Samuel Williams Jr

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    How long have you had it and is the VSC light activating? Japanese cars are extremely aggressive with "traction control," especially from a dead stop. Especially the "Prius," It will cut power and shut the motor down! Wait and then say OK, if you let off the throttle and then accelerate as "expected." A gentle touch on the accelerator is required.

    Just a thought. :)
     
  9. FuelMiser

    FuelMiser Senior Member

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    Yes, with a low SOC on the traction battery, the result is like trying to launch a manual transmission car from a stop in top gear. A lot of engine noise and no "go" In fact, the Prius ICE is always in "top gear" and the Power Split Device (PSD) feeds in torque from the electric motor(s) to assist in getting the car moving. Assuming there is sufficient traction battery power available, of course.
     
  10. FuelMiser

    FuelMiser Senior Member

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    The Prius never uses ICE for propulsion in reverse. It is always battery only, so that's why it felt normal.
    Are you sure the parking brake was not engaged, even partially?
     
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  11. Priusdude3

    Priusdude3 New Member

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    I’ve not done this yet so I will definitely look into it, even if it’s not the problem it’s probably due for a cleaning lol
     
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  12. Priusdude3

    Priusdude3 New Member

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    I think the battery was pretty low the first time it happened, It should have had a fair 25%+ charge the second time it happened but I wasn’t paying that close of attention to the battery power though due to it only happening with the gas motor primarily giving power, will test it again when I drive to auto zone today to see if I can get any codes off of it.
     
  13. Priusdude3

    Priusdude3 New Member

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    T
    the day before I accidentally drove for like five feet in my yard with it engaged, I think it was the first time I had done it, but I always put my parking break on when I park