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2010 Prius random misfire

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Nick Not Mechanic, Mar 24, 2023.

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  1. ChapmanF

    ChapmanF Senior Member

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    Legitimacy and peace of mind, mostly.

    When you get the 'alternative' downloads of Techstream that 'forget' to check your subscription, you're getting software that has been tweaked by the kinds of folks who put tweaked software up for you to download. The 'doesn't check for subscription' tweak is the one you know about. You takes your chances that they haven't included another thing or two they might like to do on your computer while they're at it.

    Also with untweaked Techstream and a paid subscription, you have the option of calling support if you're having trouble with it. And if you have a network connection, you can use the handy features where it will link you straight from trouble codes into the online repair manual, check whether your ECU firmware versions are current, and so on.
     
    #21 ChapmanF, Apr 11, 2023
    Nick Not Mechanic and douglasjre like this.
  2. veegish

    veegish Junior Member

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    Could you PM me with a little more detail on what you got? That sounds like just the setup for me!
     
    #22 veegish, Apr 16, 2023
  3. ChapmanF

    ChapmanF Senior Member

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    One little detail: XHorse was the actual name of the company that made the original, non-counterfeit, Mini-VCI dongle and its driver.

    So of course it is also what all the counterfeit Mini-VCIs and drivers claim to be. That's how counterfeiting works. So if a driver that says XHorse is the best one, then they're all the best one, but they might not all be the same. ;)
     
    #23 ChapmanF, Apr 16, 2023
    douglasjre likes this.
  4. douglasjre

    douglasjre Senior Member

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    Fleabay has loads of them
     
    #24 douglasjre, Apr 16, 2023
  5. Nick Not Mechanic

    Nick Not Mechanic New Member

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    III
    Ok, sorry for the hiatus, but I have been gone for work so I haven't been able to work on the car. Anyway, I was finally able to get the exhaust off and check the catalytic converter. Looked very clogged, but I have no idea what a clear one would look like so the real test was starting the car with the exhaust system off. Though loud, the car ran great for the 30 seconds I let it idle!!!! There wasn't any misfiring that I could hear.

    Now I will buy a cheap aftermarket CAT and figure out a way to plug off the coolant lines. If anyone has a suggestion on replacements I am all ears (and not in Cali, Colorado, nor New York :) ). Right now I am thinking worst a case scenario the car with throw code P0420, but I have read a decent amount of reviews of aftermarket ones that claim to not throw the code. They can't put anything on the internet that isn't true so they must not throw the code! ;)
     
    #25 Nick Not Mechanic, Apr 23, 2023
  6. douglasjre

    douglasjre Senior Member

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    Send pix of cat internals
     
    #26 douglasjre, Apr 23, 2023
  7. Nick Not Mechanic

    Nick Not Mechanic New Member

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    IMG_5178.jpeg
     

    Attached Files:

    #27 Nick Not Mechanic, Apr 26, 2023
  8. Nick Not Mechanic

    Nick Not Mechanic New Member

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    Not sure if this helps. Before I had taken it off I had sprayed seafoam into the O2 sensor port in the exhaust manifold which is probably why it looks relatively clean.
     
    #28 Nick Not Mechanic, Apr 26, 2023
  9. douglasjre

    douglasjre Senior Member

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    I'm confused by the statement I circled in the photo below
     

    Attached Files:

    #29 douglasjre, Apr 26, 2023
  10. douglasjre

    douglasjre Senior Member

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    Please provide the photograph of your tech stream fault codes
     
    #30 douglasjre, Apr 26, 2023
  11. Nick Not Mechanic

    Nick Not Mechanic New Member

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    Yeah, I will be honest I have no idea why I put that. I'm not sure what I was looking at, but when I first took it off, I remember thinking it looked dirty then going back the next morning and realizing it was pretty clean.

    I was holding off on Techstream since I don't believe I will ever need it again (I realize I might end up regretting that). I thought the two tests showing the exhaust manifold significantly hotter than the downstream side of the cat, along with the issue going away with the cat back off would be sufficient proof that it is indeed the Cat that is failing. Is my logic/conclusion off? I do understand that this is definitely not how one would go about working on a customer's car, but as this is my personal car I am more laxed.
     
    #31 Nick Not Mechanic, Apr 27, 2023
  12. Paladain55

    Paladain55 Active Member

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    Did you try also just unplugging the electrical connector on the EGR valve and seeing if the misfires go away? This is how we diagnose EGR issues now locally. A lot of the time people clean the EGR system incorrectly and the misfires get worse, and if we unplug the egr valve and it goes away, we diagnose it as it was cleaned unevenly so the egr flow to the individual cylinders is all out of wack.
     
    #32 Paladain55, Apr 27, 2023
  13. Nick Not Mechanic

    Nick Not Mechanic New Member

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    I did, I ran it with the EGR valve unplugged and blocked. As well as unplugged and open.
     
    #33 Nick Not Mechanic, Apr 27, 2023
    Paladain55 likes this.
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