2011 Prius P0303 cylinder misfire

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Lesdier Ortiz, May 15, 2020.

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  1. Lesdier Ortiz

    Lesdier Ortiz New Member

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    Hello,

    I'm having an misfiring on my third cylinder, I've already replaced the third coil, all the sparkplugs and all the injectors and I'm still getting the code. One thing to note is that it only happens when the gas engine starts and it is not constant it does it on a random basis and it has never happened while the car is running. Also I checked the engine oil and the dipstick looks a little weird check out the picture, do you guys have any ideas on what could be causing this issue?
     

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    #1 Lesdier Ortiz, May 15, 2020
  2. bisco

    bisco cookie crumbler

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    welcome!

    have you searched the 'clogged egr' threads?
     
    #2 bisco, May 15, 2020
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  3. Raytheeagle

    Raytheeagle Senior Member

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    Is your engine coolant level stable?
     
    #3 Raytheeagle, May 15, 2020
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah my first thought was (in hindsight) would have been better to just swap the coils around, see if the code changes. And I suspect it wouldn't.

    Second thought: the aforementioned coolant level. With tedious regularity it's head gasket failure, aided and abetted by clogged EGR (also aforementioned). The dipstick is showing some evidence of coolant?

    How many miles?
     
    #4 Mendel Leisk, May 15, 2020
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  5. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    How many miles on the vehicle?
     
    #5 SFO, May 16, 2020
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  6. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    The dipstick looks “weird” because there’s probably coolant in the oil.
    My Spidey-senses tell me you have a blown head gasket.
    There are several ways to verify, but draining the oil and seeing coolant is probably the cheapest, and believe it or not if you haven’t overheated the engine, or bent a rod all you REALLY would need to do is fix the underlying cause (EGR and some other oil fouled areas) and replace the gasket.

    If you DIY it’s a few hundred in parts and a LOT of time.
    If you pay it done, it’s a few thou.

    If all this is true, DO NOT start the car again until you get the head gasket replaced and address the other top end issues otherwise you are literally moments away from wrecking the engine.
     
    #6 ETC(SS), May 16, 2020
    Last edited: May 16, 2020
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  7. Lesdier Ortiz

    Lesdier Ortiz New Member

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    I just checked and it is about 2 inches below the Low level.

    The car has 225K.

    Thank you I'll try cleaning the EGR today.
     
    #7 Lesdier Ortiz, May 16, 2020
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  8. Raytheeagle

    Raytheeagle Senior Member

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    If it is 2 inches low, you'll need to do the head gasket while cleaning the egr circuit;).

    Good luck and keep us posted (y).
     
    #8 Raytheeagle, May 16, 2020
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  9. The Critic

    The Critic Resident Critic

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    That engine oil looks like it has coolant contamination. Between the misfire, coolant loss and your mileage, this looks like a classic HG failure.

    Don’t bother cleaning the EGR, it will not solve your problem entirely.
     
    #9 The Critic, May 16, 2020
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    #10 Mendel Leisk, May 16, 2020
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  11. pjksr02

    pjksr02 Active Member

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    Does the OP want to go through the expense of fixing the car?
     
    #11 pjksr02, May 16, 2020
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  12. Lesdier Ortiz

    Lesdier Ortiz New Member

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    Hello all, wanted to give an update on the issue, I cleaned the EGR valve and treated the head gasket with blue devil gasket sealer to try my luck, it has now been 11 days and it is running like new (fingers crossed), thank you all for the tips. I'll update this post again if the issue comes back.
     
    #12 Lesdier Ortiz, May 26, 2020
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  13. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Sounds like you got the stent in just in time.....
     
    #13 ETC(SS), May 27, 2020
  14. SFO

    SFO Senior Member

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    Any further updates worth sharing? :coffee:
     
    #14 SFO, Jul 1, 2020
  15. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Lesdier Ortiz was last seen:

    5w ago
     
    #15 ETC(SS), Jul 1, 2020
  16. SFO

    SFO Senior Member

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    In line for a bypass after using that 'blue devil gasket sealer' :confused:
     
    #16 SFO, Jul 1, 2020
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  17. Lesdier Ortiz

    Lesdier Ortiz New Member

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    Still running great, only thing I've noticed is I'm not getting the mpg I was getting before I'm around 41 mpg now...but the car does have 230k miles, so I can't ask for much more.
     
    #17 Lesdier Ortiz, Jul 1, 2020
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  18. Mendel Leisk

    Mendel Leisk Senior Member

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    Apparently stop-leak can be rinsed out, 50/50 vinegar/water solution dissolves it. Well at least one of the stop-leak products (forget which one), maybe they're all the same chemistry.
     
    #18 Mendel Leisk, Jul 2, 2020
    Last edited: Jul 2, 2020
  19. pjksr02

    pjksr02 Active Member

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    How about the EGR cooler, and the intake manifold?
     
    #19 pjksr02, Jul 4, 2020
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  20. crazylife

    crazylife Junior Member

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    I'm late to the "game" on this - but having the #2 cylinder misfire - and engine coolant is a bit low on both areas. Would love some advice. I have replaced spark plugs and coils (all of them). Still makes the loud start up noise just more often and occasionally is missing on start after a stop now.
     
    #20 crazylife, Aug 15, 2023
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