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2008 misfire diagnosis

Discussion in 'Gen 2 Prius Technical Discussion' started by Kaip123, Jun 4, 2024.

  1. Kaip123

    Kaip123 New Member

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    Hello, I’m a proud owner of a couple 2008 priuses and love them to hell and back. One recently started doing the death rattle and it doesn't go away (it was sudden and while slowly driving out of my complex). It has 330k miles and a newer engine I swapped in about 40k miles ago. It wasn’t showing a CEL and it also has a bad cat that I have a replacement for but haven't replaced. I recently replaced my valve cover gasket, spark plugs (NGK iridium) and coils with rebuilt denso coils (within 10k miles). The gasket seated properly and isn't leaking oil into the spark plug holes. I decided to clean the injectors i have from an old engine and swap them into my car as I thought that is the only thing I haven't done and the last common issue that causes the death rattle. The computer didn't immediately adapt so I unplugged the 12v for 3 minutes and that alleviated some of the rattle though it’s intermittently reoccurring. Now, however, it’s finally throwing a code (P0300) when it wasn't before. I’m a little stuck on where to go from here or how to test either the spark plugs or ignition coils. Does anyone have any tips on where to go from here?
     
  2. Kaip123

    Kaip123 New Member

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    I forgot to say that I also replaced the upstream o2 sensor with an OEM one during the engine swap and just replaced my downstream as it read 0.000 in my scan tool so everything is new there too.
     
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  3. Tombukt2

    Tombukt2 Senior Member

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    I think zeros is more or less what you would get with the engine not running or the car not running nothing for the O2 sensor to c if the ice engine isn't on I think unless the heater circuit then again the ignitions or system has to be on for the heater circuit to even work in the O2 sensor.
     
  4. Tombukt2

    Tombukt2 Senior Member

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    Death rattles extremely rare and a generation 2 the 1NZ is generally not about that kind of nonsense so did the death rattle develop 40,000 mi ago or how did this start Just one day you woke up and you had the death rattle many times that's usually water getting in the cylinder putting the fire out in the cylinder not oil as the last ditch resort You can take the spark plugs out of a generation 2 without taking the car apart and look in the spark plug holes with a boriscope You're looking for fine water droplets If you're really on top of it when you pull your plugs out like first thing in the morning You can take a magnifying glass and look for fine water droplets on the very tips of your spark plugs If you see those fine miniature water droplets Stick your finger on it then stick it to your tongue does it taste like ethylene glycol bingo.
     
  5. Kaip123

    Kaip123 New Member

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    Hello, thanks for the replies and help diagnosing! I ended up using tech stream once i found my cable for it and got a reading that cylinder 4 was misfiring. I swapped my cylinder 4 ignition coil with one i had around and that solved my problem. Definitely can’t trust the denso coils on ebay.
     
  6. Tombukt2

    Tombukt2 Senior Member

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    No I bought some aftermarket TRQ things I think they were 80 bucks or something for the set so far so good they're supposed to be higher performance tighter windings I have no idea but something and there's an aftermarket coil maker in seller on eBay that sells some pretty nice looking supposedly higher performance coils very reasonable I haven't heard any bad things about them yet but they haven't been around long enough to probably get any reviews like that but I generally haven't had trouble with coils buying what seems to be reasonably well built brands from whoever for whatever I'm working on If you buy the cheapo . Then more than likely you'll get those kind of results I guess