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Engine running too frequently and longer

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by srivenkat, Mar 14, 2013.

  1. srivenkat

    srivenkat Active Member

    Joined:
    Feb 28, 2011
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    Location:
    IL
    Vehicle:
    2021 Prius Prime
    Model:
    XLE
    Folks,

    I used to get great MPG's in the beginning (>57 MPG in summer) that deteriorated as the engine started to run longer and more frequently after what I suspected to be a faint bump against a garage wall in the front. This was several months ago. I have since been averaging about 47 MPG overall (averaging winter, summer out). I forgot about the bump incident until last week when the engine suddenly started running shorter and less frequently. This lasted for a week or so, with no significant changes in the weather/temperature. And then inexplicably, it has started to run longer and more frequently again. By "more frequently", I mean when I bring ICE on, it doesn't easily quit, regardless of my prodding it to quit by going into regen momentarily. Also, the initial warmup is longer.

    No codes or anything on the dash, but is there anything in the front (such as a thermostat wire or something) that may have become loose and such that could be causing the computer to think the engine is not warm enough causing it to run ICE longer and more frequently than is actually required?

    Thanks.
     
    #1 srivenkat, Mar 14, 2013
  2. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
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    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Since winter cold and winter fuel affect MPG significantly, the suggestion to do in the meantime is get a bluetooth transmitter (for about $20) and observe the change spring has firsthand. Watching coolant temp and engine rpm can be extremely informative. With the Torque app (for just $5) you can even capture datapoints for comparison.

    I doubt anything is actually wrong. But if you want something solid to prove or disprove, that is the way to go.
     
    #2 john1701a, Mar 14, 2013
    TwoUnderPar likes this.
  3. rrg

    rrg Active Member

    Joined:
    May 18, 2010
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    Location:
    East coast - NJ
    Vehicle:
    2011 Prius
    Model:
    Two
    If the weather is warmer in IL then don't run the heater fan for the heat/cool air. The engine should turn off at every stop sign or stop light after initial warm up stage, mine does. If it runs then you might try to unplug the 12v battery over night and see if a reset helps.

    I also got 57-58 in summer time and slowly lost that. Mostly due to a warm up in the drive way on cold mornings. I hate to push the engine hard on the highway during my commute with out a good warm up, IMHO.

    I also drive to work one day a month with radio off and no fan to listen and learn how the car ICE runs or does not run on my commute.

    my2cents.
     
    #3 rrg, Mar 15, 2013
  4. cwerdna

    cwerdna Senior Member

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    2006 Prius
    #4 cwerdna, Mar 15, 2013
  5. The Critic

    The Critic Resident Critic

    Joined:
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    2011 Prius
    Model:
    Three
    It's hard to say without plugging in a real scan tool and collecting some data. One thing that you could do, is have to have the 12v battery tested using a Midtronics tester - not the infamous voltage method suggested by some.
     
    #5 The Critic, Mar 16, 2013
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