Help! 2010 cylinder misfire PO 302

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by 2010five2015five, Oct 18, 2021.

  1. 2010five2015five

    2010five2015five New Member

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    I have 205,000 miles on my 2010 Prius five and mostly highway miles, run synthetic mobile one oil changed every 5k and fluids always before needed, dealer replaced EGR Valve about 8 years ago, I’ve done the pipe cleanings periodically, this summer I had some codes first po445 turned out to be the purge sensor then I got a pending on my scan gauge for O2 sensor so I replaced both of those before check engine light came on then a PO300 302 304 I was not using any coolant but bought a test kit anyway and it tested negative for coolant leak, I’ve replaced néw with all genuine Toyota parts the plugs, coils, fuel injectors, intake manifold,PVC valve MAP sensor MAF sensor bought a newer EGR cooler off eBay and it was clean but I pressure washed it to shiny clean before install, bought a new EGR valve off EBay and looked good and new ran, great first few times but then after a couple days a slight rattle at start up like only 1 second and the next start up a 1-2 second rattle again and check engine light comes on again, also replaced 12 volt battery as that seems to be a culprit when they are weak, I don’t know what I’ve missed, if it’s not a head gasket what else is left, I read somewhere here that sometimes replacing the EGR valve requires a computer software update, but wouldn’t that have been apparent right from the first start up after install? Could I have got a defective new coil? I’m out of what else can it be’s! Greatful for any ideas and help are greatly appreciated !
     
  2. rjparker

    rjparker Senior Member

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    Did you have rattling before all the new parts? If so, were they also short term startup rattles?

    Are the "after new part rattles" continuing or did they occur only twice?
     
    #2 rjparker, Oct 19, 2021
    Last edited: Oct 20, 2021
  3. JC91006

    JC91006 Senior Member

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    Wow you really threw a lot of money at this thing. Replaced part after part.

    What test did you use for coolant leak? Leakdown test?

    95% of all these misfires on a Gen3 engine, results in a headgasket failure. Especially at high mileage
     
  4. 2010five2015five

    2010five2015five New Member

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    Thanks for replying JC yes I had a few cold rattle starts always short and never throwing codes
     
  5. 2010five2015five

    2010five2015five New Member

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    Hey JC thanks for responding I had a few cold rattle starts before replacing everything, but very short few seconds rattle then run like normal, and it was not throwing the codes either
     
  6. 2010five2015five

    2010five2015five New Member

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    Sorry I meant RC
     
  7. 2010five2015five

    2010five2015five New Member

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    Hey JC it was Bock tester BT-500

    Yeah I’ve read up on that here, that’s why I was surprised not to have been loosing fluid and a negative coolant leak test, I also read a lot of the problems begin with the EGR system blockage , and occasionally bad coil packs, I wonder about the plug wires one of the few things I have not replaced or a vacuum leak, my mechanic said it may be a sticking valve?

    Most of the parts I replaced I had wanted to do anyways as general maintenance going into the 200,000’s I also put in a new water pump while doing the EGR cooler and new coolant
     

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    #7 2010five2015five, Oct 20, 2021
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  8. JC91006

    JC91006 Senior Member

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  9. rjparker

    rjparker Senior Member

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    Many have reported the same thing but ultimately it was a head gasket. Some that replaced the gasket themselves and found no breach of the metal head gasket but could see the steam cleaned coolant path into the cylinder and the steam cleaned piston. If the coolant leak primarily occurred after a cool down and cleared fast on restart (cold start rattle), the leak could have been very small and likely sealed after increasing engine temp expanded parts. The chemical coolant leak test depends on an active leak during the test.

    I like a borescope cylinder inspection as a more definitive early stage indication. I have seen engines start to leak and the borescope told the story. I have also seen similar leaks with a single loose head bolt.

    It almost seems Toyota may have cross trained with Subaru engineers on the gen3 design.
    SUBARU x TOYOTA Let's make ever-better cars together! | Subaru Corporation
     
    #9 rjparker, Oct 21, 2021
    Last edited: Oct 21, 2021
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  10. OptimusPriustus

    OptimusPriustus Junior Member

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    Has there ever been a poll about HG failure? In Priuschat i mean. We should collect data (model year, mileage&year symptops showed up, climate car was used at, maintenance etc) and do the math. We could pull out likelihoods and hopefully rule out some of the factors we now think have key role. Would be fun&usefull:)
     
  11. JC91006

    JC91006 Senior Member

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    The factors that cause HG failure, should be clogged EGR/Intake and water pump failures. If these are ignored and not part of maintenance routine, then you'll very likely become part of the HG failure statistic
     
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  12. OptimusPriustus

    OptimusPriustus Junior Member

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    But they are not part of maintenance routine as per Toyota. Yet, there are millions of Priuses (+other Toyota with same engine) on the road including mine with 212kkm on the clock and egr never cleaned.

    i checked a video where guy cleaned manifold. Amount of carbon was so little that statistically people do more damage than good with such DIY jobs. There is always some carbon in egr car manifolds
     
    #12 OptimusPriustus, Oct 21, 2021
    Last edited: Oct 21, 2021
  13. JC91006

    JC91006 Senior Member

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    You can't really depend on the manufacturer to know everything about their cars. They can only recommend in their literature if they know in advanced the problems the car will have. I have changed out the water pump and cleaned EGR at under 135k miles on my Prius, just as a preventive measure. Not sure if mine was problematic, but doing it so helps me sleep better at night.

    In the example of Porsche 911 models from 1999-2007, they had a bearing failure in many of their cars engines. Many owners took it upon themselves to replace the bearing even though Porsche didn't have that replacement in their maintenance schedule.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    The whole of the EGR system up to the intake manifold is monitored, so if you are of a mind to leave well enough alone until there is a reason to fuss with it, you can just pull up the monitor results from time to time and see how it is doing.

    The intake manifold itself is a little different story, because the method used for monitoring the EGR isn't able to tell if the four manifold passages are clogged by different amounts. That can definitely turn out to be a culprit if you have rough-running symptoms at mid-loads, but not at idle or full throttle when EGR isn't used. If there's anything to the EGR ⇒head gasket causation often talked up here, that uneven manifold clogging may be a better explanation for it than some of the others on offer.

    Because of that, and because the monitoring doesn't cover it, and because the manifold itself is a pretty easy job, even I (not a strong defender of the EGR ⇒head gasket theory) did clean mine a year and a half ago or so to see what I would see. Admittedly, there wasn't a whole lot of carbon in mine, but there was some.
     
  15. 2010five2015five

    2010five2015five New Member

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  16. 2010five2015five

    2010five2015five New Member

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    These are some cylinder shots I took with my DEPSTECH inspection scope, I don’t know what to make of it other than lots of noticeable carbon buildup!
     
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