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Cruise surge at 60

Discussion in 'Gen 4 Prius Main Forum' started by Recian, Jan 3, 2022.

  1. Recian

    Recian Junior Member

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    Sep 1, 2019
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    Location:
    New Bern, NC
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    Other Non-Hybrid
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    2018 prius four. I've been meaning to bring this up for awhile but this morning weather was bad so front sensor got dirty and I was forced to use normal cruise control. 55-62~ mph with cruise set it surges. Enough to fluctuate between 45 and 80 or so mpg on mpg meter, 1/5 of the HV monitor and almost makes you sick. Speed stays steady at 60. With adaptive cruise this isn't a thing. Stays steady around 55mpg. It's been this way since I bought it last year at 34k. Almost like it's normal but there has to be a reason for it and a possible fix. Has anyone been through this?
     
    #1 Recian, Jan 3, 2022
  2. jerrymildred

    jerrymildred Senior Member

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    Oct 28, 2016
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    Tampa, FL
    Vehicle:
    2017 Prius
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    Two
    When you're in adaptive cruise, are you following a car or is it wide open road in front of you while it's running smoothly? I ask because, I wonder if it might be a flaky speed sensor that throws it off in regular cruise but gets ignored if the radar is giving input to the throttle control. I don't know all the details of how it works but there must be a difference in the feedback loop that dampens that throttle hunting.

    I think I'd take it to the dealer.
     
    #2 jerrymildred, Jan 3, 2022
  3. Recian

    Recian Junior Member

    Joined:
    Sep 1, 2019
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    Location:
    New Bern, NC
    Vehicle:
    Other Non-Hybrid
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    N/A
    It is smooth open road or with cars in front of me as long as I'm using adaptive. When I try to research the issue I see complaints of this issue on highlander and dealers are telling them its normal. It shouldn't be normal for cruise to do that especially when ignoring the radar distance sensor. When I first got the car at 34k dealer told me toyota doesn't see the C pillar peel as a defect and blew me off getting those fixed so I don't put it past them to blow this off as normal and waste my time.
     
    #3 Recian, Jan 7, 2022
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