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P0304 MISFIRE ON CYLINDER 4

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Catalinux, Feb 13, 2013.

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  1. Catalinux

    Catalinux Junior Member

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    Hi all,
    Well, I have a big problem on prius 3, the problem is that it has a big and I mean a big body shake when I decelerate above 30 mph or slowly accelerate above 30 to 50-70 mph, when I fully accelerate, the body shake disappears. When the body shake occures MIL comes blinking and DTC P0304 comes but not always, but the shake is only when the coolant is hot.
    On the other hand, if the MIL is not on with the tester it can be seen that the cylinder 4 has misfire margin, only cylinder 4, every time.
    Now what I have done is to exchange the injectors, problem remains on cyl4,
    -replaced the coils, problem remains on cyl4,
    -clean the EGR, problem remains on cyl4,
    -opened the engine to see the valves, cylinders, pistons, exchanged the ring set,problem remains on cyl 4,
    Replaced the wheels, the problem is still there, now I want to replace the drive shafts.
    So if anyone had a similar problem please let me know.
    Thanks
     
    #1 Catalinux, Feb 13, 2013
  2. pjksr02

    pjksr02 Active Member

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    What year is your Prius (profile says 2001, and this board is for Generation-III). How many miles?

    What would the drive shafts have to do with misfiring on a single cylinder?

    The Repair Manual list the following trouble areas for a (blinking) P301-4 code:

    - Open or short in engine
    wire harness
    - Connector connection
    - Vacuum hose connections
    - Ignition system
    - Fuel injector assembly
    - Fuel pressure
    - Mass air flow meter subassembly
    - Engine coolant
    temperature sensor
    - Compression pressure
    - Valve timing
    - PCV valve and hose
    - PCV hose connections
    - Intake system
    - EGR valve assembly
    - ECM
     
    #2 pjksr02, Feb 13, 2013
  3. Catalinux

    Catalinux Junior Member

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    Yes, is not for my car indeed, is for a prius 3 (a friend of mine), year is 2009, tha car has 190.000 miles. I checked what you said but also in the RM says that if you have a extremely unbalanced wheel/drive shaft it could cause a vibration leading to misfire, of course not on one cylinder nut now i'm checking all possibilities. Thanks
     
    #3 Catalinux, Feb 13, 2013
  4. BZzap!

    BZzap! Senior Member

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    Have you done a compression check? You didn't mention anything about the cylinder head and valve train. You might have a burned exhaust valve. Do a compression check.
    Foot note:
    I see you said something about compression??? The only other thing is to see if the coil on that cylinder has a signal. Try a droid light.
     
    #4 BZzap!, Feb 13, 2013
  5. Catalinux

    Catalinux Junior Member

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    I checked the compression and it is in the normal range, 6.2 bar/cyl, cylinder head was checked because I replaced the piston rings, I checked the valves (intake & exhaust), they are all fine, an yes the coil has signal.
     
    #5 Catalinux, Feb 14, 2013
  6. BZzap!

    BZzap! Senior Member

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    Well, it appears that you have left no stone unturned. Sometimes the most obvious things can turn out to be the culprit. The one you least expect is usually the case; for example, a cracked spark plug. All I can offer at this point is, good luck.
     
    #6 BZzap!, Feb 14, 2013
  7. Catalinux

    Catalinux Junior Member

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    thanks, but the spark plugs were replaced with new ones (as a precaution at the begining of the repair), now I'm focusing on replacing the crankshaft position sensor with a new one, this can cause what I'm experiencing, and also the camshaft pos sensor. I measured with the oscilloscope the signal of the crankshaft and it seems that I have misfires on several pistons, thus being Atkinson cycle it is very sensitive to firing order and misfires, corect me if i'm wrong, dispite other 1.8 l engines.
     
    #7 Catalinux, Feb 14, 2013
  8. BZzap!

    BZzap! Senior Member

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    The crankshaft sensor could very likely be the problem, especially with multiple misfires on random cylinders. At 199,000 miles it is way beyond the "maybe" point. Hot oil and engine heat cause the pick-up coil on the sensor to crack. Again, Good Luck! Oh, BTW, don't think for a moment that all the other e repairs were in vain. That's a lot of miles.
     
    #8 BZzap!, Feb 14, 2013
  9. Catalinux

    Catalinux Junior Member

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    Hello, unfortunatly it is not the cranshaft sensor or the camshaft sensor, i'm back to the beginning, now i shoul remove the transaxle because i hear a noise there that is very unusual. If you have any ideeas at all please reply.
    Thanks,
     
    #9 Catalinux, Feb 15, 2013
  10. BZzap!

    BZzap! Senior Member

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    Don't rule out a bad CV joint.
     
    #10 BZzap!, Feb 15, 2013
  11. Catalinux

    Catalinux Junior Member

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    And by CV joint you mean....
     
    #11 Catalinux, Feb 16, 2013
  12. bisco

    bisco cookie crumbler

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    constant velocity joint joins the 'transmission' and axles/wheels, inside the rubber boots.
     
    #12 bisco, Feb 16, 2013
  13. Jonny Zero

    Jonny Zero Giggidy

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    Why would a misfire have to do with a bad CV joint?
     
    #13 Jonny Zero, Feb 16, 2013
  14. BZzap!

    BZzap! Senior Member

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    If you read the OP's first post, he has even contemplated removing the drive shaft. So, it seems to me that he is perplexed as to the cause of the "body shake". At this point he is obviously grasping at straws. His discription of the cause and effect has a very broad range of possibilities.
     
    #14 BZzap!, Feb 16, 2013
  15. Catalinux

    Catalinux Junior Member

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    Yes, with this car I'm older with 10 years because of the broad range mentioned by BZzap!
    At this moment I'm taking off the transaxle to check the differential, it has an unusual noise inside.
    Let you know what I discover.
     
    #15 Catalinux, Feb 18, 2013
  16. Catalinux

    Catalinux Junior Member

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    No, it is not from the transaxle, but i discovered that it seems to be a problem in the intake manifold... i'll get back to you with the result.
     
    #16 Catalinux, Feb 18, 2013
  17. Catalinux

    Catalinux Junior Member

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    Solved it, the problem was inside the intake manifold, every cylinder has a correspondent (pipe inside the manifold) from the EGR, the pipe of the cylinder 1 and 2 were clogged, now the burned gases were returning at constant speed and were entering in cylinder 4 causing misfire. After I cleaned the intake manifold EGR piping inside the intake, the car is running well. Thanks for help ;)
     
    #17 Catalinux, Feb 19, 2013
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  18. jdenenberg

    jdenenberg EE Professor

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    That's a nice job of tracking down your issue. I'll keep in in mind if my 2004 Prius (237k miles) ever has misfires. The build up in those intake pipes may indeed be due to the unburnt fuel mixture entering via the intake valves during the compression stroke.

    JeffD
     
    #18 jdenenberg, Feb 19, 2013
  19. retired4999

    retired4999 Prius driver since 2005

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    Wow! Nice Job!
     
    #19 retired4999, Feb 19, 2013
  20. adamace1

    adamace1 Senior Member

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    Wow... Just wow.
     
    #20 adamace1, Feb 19, 2013
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