Throttle jumpy when trying to maintain speed.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by zoeboi954, Jul 21, 2025.

  1. zoeboi954

    zoeboi954 Junior Member

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    So when im driving to maintain a certain speed like for example trying to drive at 45mph the throttle input (mpg) start to become slightly jumpy. it would jump from about 40 mpg to 80mpg while I am keeping the same pressure on the gas pedal. You can feel the difference in acceleration when it happens..
    info about the car 2013 prius with an 2018 gen 4 engine euro/jdm version.

    Has anyone experienced this? how do I fix it?
     
    #1 zoeboi954, Jul 21, 2025
  2. NutzAboutBolts

    NutzAboutBolts Senior Member

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    No check engine light?

    did it do that before?

    I wonder if it could be the engine swap parts that is affecting the engine signals. Your speed looks to be maintained besides the mpg gauge on the right.
     
    #2 NutzAboutBolts, Jul 21, 2025
    Mendel Leisk likes this.
  3. Grit

    Grit Senior Member

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    You should be blessed If car goes From 40 was To 80 mpgs
     
    #3 Grit, Jul 22, 2025
  4. ChapmanF

    ChapmanF Senior Member

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    I find there are some combinations of road speed, grade, and so on, that end up being right close to the car's "should I use engine power for this or just battery?" decision threshold, and it'll go back and forth a bit. Car might just be doing what it does.
     
    #4 ChapmanF, Jul 22, 2025
  5. CR94

    CR94 Senior Member

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    True. MPG should be alternating between some moderate number and the maximum it shows, 100, not 80. I try to avoid that condition by alternating as needed between slightly greater engine power and coasting with engine off.
     
    #5 CR94, Jul 22, 2025
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