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Is this really a bad ECM?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by harpstar13, Sep 27, 2018.

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  1. harpstar13

    harpstar13 New Member

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    2005 Prius
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    Hi there,

    We have a 2005 Prius that started running really rough and check engine light came on while driving it home. After that, whenever we tried to start it up the shaking/rough idle would continue and then the car would stall. Husband also reported to me that he smelled sulfur.

    We took it to a mechanic who said it had 2 bad ignition coils and spark plugs which he replaced. $600 later, the car is running better, no smell and the rough shuddering is gone - but the check engine light is still on. At start up it takes a few seconds longer than usual for the engine to engage and I can hear this little hiccup in the engine, although it seems to go away when I start driving. Drives fine.

    The mechanic said it was still misfiring and that it had ECM problems. He said I needed to take it to a Toyota dealership soon and not to drive it too much or I ran the risk of damaging the catalytic converter.

    The problem with this is that a trip to a dealership requires a full day off from work and a ferry ride which is very costly. Before I do this - does anyone agree that the ECM could be causing this problem or should I get a second opinion? Is there anyway for me to reboot it myself? (If that's the right term). Or should I really take it to the dealership?

    Thanks for any advice!
     
    #1 harpstar13, Sep 27, 2018
  2. exstudent

    exstudent Senior Member

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    What codes did the mechanic report, after the coil and SP replacement?

    Order mini VCI off Amazon ($25-$35). Prime shipping, 2 days arrival. The hacked Tech stream software that comes w/ the cable or avail off Internet, will give you dealer level diagnostic capability. Tech stream is what the dealers use b/c it was written for Toyota/Lexus, and approved by Toyota.

    Best installed in a old 32bit Windows OS (XP, Vista, 7) laptop. Ask friends/family/coworkers if they know anyone in IT. This person will likely have a few obsolete laptops collecting dust. Install on a Mac is possible; you will have to research this yourself.
     
    #2 exstudent, Sep 29, 2018
  3. SFO

    SFO Senior Member

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    How many miles on this vehicle, and have you owned it for very long?
     
    #3 SFO, Sep 29, 2018
  4. bisco

    bisco cookie crumbler

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    you can disconnect the 12v negative for an hour. and check the gas cap.
     
    #4 bisco, Sep 29, 2018
  5. JC91006

    JC91006 Senior Member

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    The check engine light is usually emissions related, not ECM issue. The misfiring could be a number of issues and there should be codes stored for this error.

    I would have him clean the throttle body and MAF sensor first. Then check the fuel injectors.
     
    #5 JC91006, Sep 29, 2018
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