2002 prius engine surging at idle and continuos

Discussion in 'Generation 1 Prius Discussion' started by IAN HIGGINS, Oct 23, 2021.

  1. IAN HIGGINS

    IAN HIGGINS New Member

    Joined:
    Oct 23, 2021
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    Location:
    Bahia de Los Angeles, Baja California, Mexico
    Vehicle:
    2002 Prius
    Model:
    Base
    So I swapped out the hybrid battery with a besthybrid battery remanufactured one. Then serviced the engine, changed spark plugs, cleaned throttle body, replaced pcv valve. All throttle body components very dirty. I thought now should pur like a kitten, and get great mpg...but now surges at idle and horrible mpg.

    It starts up at idle ok, then about 15 seconds in revs high and starts to surge, plus some serious rambling noises from under the engine bay. What could this be?

    Any help much appreciated!
     
    #1 IAN HIGGINS, Oct 23, 2021
    Last edited: Oct 23, 2021
  2. dolj

    dolj Senior Member

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    Vehicle:
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    Hi and welcome to PriusChat.

    FYI, your posts are moderated until you have had five or more moderated posts. This is an anti-spamming countermeasure. :-(

    The EMC (a/k/a engine ECU) is seeing that things have changed and has started a process of recalibration.

    You can jump-start this procedure by disconnecting the 12 V power at the 12 V battery for 20 or 30 seconds. Doing this will reset many of the variable or learned values back to default values. The default values will be much closer to what the system expects now that you have cleaned everything.

    I hope that helps.
     
  3. IAN HIGGINS

    IAN HIGGINS New Member

    Joined:
    Oct 23, 2021
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    Location:
    Bahia de Los Angeles, Baja California, Mexico
    Vehicle:
    2002 Prius
    Model:
    Base
    Thank you very much for responding. I did try that, I unplugged both the hybrid battery and 12 volt battery waited a little while and plugged back in and tried. It keeps doing the same thing. The surging is a very regular surging up and down. It really seems to me like a sensor, maybe I somehow damaged the mass airflow sensor or somehow the EGR was effected? Would it act that way with a damaged mass air flow sensor, or EGR?

    It hasn't given a code yet, but I'll drive it a little more and wait for a check engine light to come on.
     
  4. Stock808

    Stock808 New Member

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    Oct 12, 2021
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    Location:
    Hawaii
    Vehicle:
    2001 Prius
    Model:
    N/A
    Plug in OBD2 Scan tool, maybe while revamping the engine you damaged a vacuum line. Check the fuel trim levels while the engine is on.

    or just keep driving it till a code pops up
     
    SFO likes this.
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