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2005 Prius w/ "rod knock" - Looking for 2nd opinion

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by random_username, Jun 21, 2022.

  1. random_username

    random_username Junior Member

    Joined:
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    Vehicle:
    2005 Prius
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    N/A
    @dolj Just saw your reply to the pic I uploaded. Thanks for explaining how uploading works -- I'm still figuring out the site.

    I wanted to include your question here, to keep the info as consolidated as possible.

    In response to the picture below, dolj asked:
    Actually that COP was from the well with the rusted in plug. There has been no oil issues so far (fingers crossed!). I dried it out and I haven't observed any water since.

    So the residue on the COP wasn't oil. Whatever it was, it seemed "baked on". It didn't come off when I rubbed it with my finger, but came off eventually with a damp cloth. Maybe there was some moisture in there that I missed and it mixed with the rust and then heated up and dried on the tip?

    I don't know. I don't feel any closer to an answer. My cheap little ODB2 reader had only picked up the misfire faults originally, so now I'm wondering to what extent the other codes might be related...
     

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  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Engine coolant level in the reservoir is stable?
     
  3. dolj

    dolj Senior Member

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    The first thing you will absolutely need to do is disconnect each of the fuel injectors. To accomplish both procedures would be to remove the COP you want to test and then the spark plug and then put that into the end of the COP. Attach the signal wire that usually plugs into the top of the COP, ensure the threaded portion of the spark plug is grounded then turn the engine over. If the COP is functioning (and receiving the signal from the ECM) you should see a spark (and hear a crack as it sparks – tick-tick-tick etc) crossing the gap of the plug. You probably will need a scan tool like Techstream to carry out this although you might be able to use inspection mode to crank the engine.
    While those voltages are not great and you should definitely charge that battery up to full (then test it to make sure it bounces back to the starting voltage (12.7-12.9+ V) after a load is applied for 30 to 60 seconds - headlights on, for example), I don't believe it has a lot to do with the rough running. At this stage, I would hold off on letting this distract you from finding out what is the cause of your misfires. Even though, I will give some information about the C1218 and the C1241 just so you can get an idea of what those are about. Still, don't get distracted by those, focus on getting the misfires fixed.

    C2318

    The auxiliary battery voltage is applied to terminal +B when the power switch is IG-ON. The transmission control ECU outputs this DTC when the input voltage drops. Both conditions below need to be met:
    • Power switch ON (IG)
    • Terminal +B voltage of the transmission control ECU is 9.3 V or less for 1 second or more,
    This could be because the auxiliary is discharged but it could also be the HEV fuse, IGCT relay, or the wire harness or connector. Following the steps in the repair manual will steer you in the right direction.

    Full Diagnostic here DTC C2318 | Low Voltage Error (Power Supply Malfunction)

    C1241

    This one is actually reporting the voltage that arrived at the skid control ECU and it is not necessarily the battery voltage. Further, if you look at that voltage in the freeze frame data (FFD), which I suspect your scanner is not capable of doing, then you will see what the voltage was at the time the code was set. You can also see from the FFD whether the car was in motion at the time, and therefore in READY state. If the car was READY, that takes the 12 V battery out of the picture because in READY the 12 V power is coming from the inverter's DC/DC converter. If the DC/DC converter was not supplying voltage, then that could run down the battery as that would be supplying all the 12 V power. So you can see it is not so simple to draw any immediate conclusion without first doing some investigation. At this point, you really need a scanner that can display the FFD and a copy of the repair manual so you know what steps you need to do to diagnose this.
    Yes, I think that is what it was too, rusty water that got sprayed on it. The water still most likely spilled over from the wiper tray, though.

    I hope that all makes sense. If you have any questions please ask. I or someone will jump in and answer them.
     
    #23 dolj, Jun 26, 2022
    Last edited: Jun 26, 2022
    SFO likes this.
  4. random_username

    random_username Junior Member

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    2005 Prius
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    Yep, no noticeable drop since I've had the car

    Thanks for all this info! It's super helpful. I'll try testing the coils ASAP and report back.
     
  5. random_username

    random_username Junior Member

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    Location:
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    Vehicle:
    2005 Prius
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    BTW, I took the PCV hose off while the car was running and there was no change. It was hissing, so air was coming through, but the RPM didn't drop or anything. Is that normal?
     
  6. random_username

    random_username Junior Member

    Joined:
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    Location:
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    Vehicle:
    2005 Prius
    Model:
    N/A
    Got around to testing the COPs and saw one wasn't sparking. Replaced the one ignition coil and the problem seems to have 100% cleared up! I still have to drive it around more, but it feels great right now and there are no more CELs. @dolj nailed it.

    To think of the scam artists who took my $200 to diagnose the vehicle and quoted me another $10,000 for what turned out to be a single bad coil. On the flipside, I've gained some valuable experience working on Prii now. Hopefully I'll be able to keep it running for another 100,000 miles!

    Many thanks to everyone who chimed in on this thread. What a great community. I really appreciate it.
     
    SFO likes this.