Rough Startup that goes away after 15-20 secs

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriuSocal, Apr 4, 2023.

  1. PriuSocal

    PriuSocal Member

    Joined:
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    Vehicle:
    2008 Prius
    Model:
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    Hey guys so trying to help diagnose this for fellow prius owner and looking for some ideas as youtube is all over the field when looking up this symptom. So the issue is a rough / shaky engine while starting up in the AM (sorta like when a car is running out of gas). The shakiness will last for 10-20 seconds then goes into a normal steady idle.

    The car: 2007 Prius
    Miles 230k
    NO CEL on
    No overheating
    Good 12v Battery
    Good HV battery
    Oil change done on time
    Oil nice and clear

    Other notable mentions:
    The car runs and drives fine according to owner but he also stated, the car tends to burn more oil than before. I have seen some say head gasket (but usually comes with other symptoms he doesn't have), some say dirty MAF sensor etc but want to get more ideas from you all to see if we can help him get closer to his issue and possibly resolve it.

    Thanks in advance
     
    #1 PriuSocal, Apr 4, 2023
  2. PriusCamper

    PriusCamper Senior Member

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    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    If it was a 2010-2015 Prius you'd have serious concerns, but with a 2004-2007 it could simply be the nature of the Atkinson engine if symptoms are intermittent and don't get worse.

    But at 230K it's probably wise to change the spark plugs and air filter, clean the throttle body and mass air flow sensor and disconnect the 12v briefly to reboot the system.
     
    #2 PriusCamper, Apr 4, 2023
    PriuSocal likes this.
  3. PriuSocal

    PriuSocal Member

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    I was going to advise on the MAF sensor for starters. I know the air filter is new as I inspected it myself. MAF, TB and Spark Plugs sound like wise things to change as well. Thanks for the input!
     
    #3 PriuSocal, Apr 4, 2023
  4. SFO

    SFO Senior Member

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    Might try doing a pistion soak with the right solvent.
     
    #4 SFO, Apr 6, 2023
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