Cylinder 2 misfire at 1500-1700rpm please help diagnose

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by bikes4u, Aug 5, 2019.

  1. bikes4u

    bikes4u Member

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    Here is what I got on compression check....

    #1 dry 170. 2 175, 3 167, 4 165

    #1 wet 183. 2 200. 3 178 4 188

    This to me indicates not a blown head gasket since it doesn appear to be leaking compression between cylinders. Keeping in mind there is no anti freeze loss.

    Is there anything from these readings that would indicate a problem? Thanks

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  2. bikes4u

    bikes4u Member

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    Also.... I've noticed this misfire starts when the engine is warm. When it is cold it runs smooth.

    The misfire only occurs at 1500 to 1750 RPM cylinder 2 when engine is warm.

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  3. msg4life

    msg4life Member

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    Again... I will say this it's the egr cooler. . It's clogged.. When the engine is cold.. The egr valve is closed... When the temperature is set the egr opens.. The computer makes adjustments if it doesn't get the proper egr gas.. Then the cumbustion if now miscalculated.
     
  4. bikes4u

    bikes4u Member

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    For just cylinder number 2?


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  5. bikes4u

    bikes4u Member

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    I'm changing the manifold gasket and notice the egr pipe does have suet in it but not near plugged.. Its definitely possible.

    I will unplug the egr valve and see if it runs the same.

    Looks like another cleaning may be coming soon. It also looks like the OCC does not do much to prevent suet buildup.

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  6. CR94

    CR94 Senior Member

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    That could occur if egr passages in the intake manifold are unequally clogged.

    Soot is more likely than "suet," unless the car has been fueled with animal fats.
     
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  7. bikes4u

    bikes4u Member

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    Interesting.. It does appear something is plugged in the EGR circuit. I unhooked the egr valve and it's not misfiring so far. I wish I knew it was that easy to check it could have saved me some money and lot of time with other parts. Oh well

    I'm disappointed that the OCC doesn't do much for the soot buildup.

    I'll report back if there is any changes. Thanks for everyone's help and insight

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  8. cnc97

    cnc97 Senior Member

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    If there was a CEL I would agree. Absence of EGR flow would normally trigger a CEL. If there is no EGR flow, the fuel map is going to revert back to the no flow fuel map.
     
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  9. msg4life

    msg4life Member

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    Not always the case. I've seen plenty of forums describing your issue. With no check engine light. The egr cooler was clogged enough to give your symptoms. I can bet you it's clocked and either needs to be cleaned or replaced.. It's a design flaw because it is located before the cat. Unlike the gen 4.
     
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  10. msg4life

    msg4life Member

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    Okay so we are dealing with different issues. Occ is to help the start up knock from cold weather the water and blowby built up in the intake. That can cause headgasket failure.. Egr cooler and valve uses exhausted fumes that are quite dirty to cool the cylinder and help with mpg. But because of a design flaw the cooler must be cleaned every 60 to 100k.
     
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  11. msg4life

    msg4life Member

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    Oh and YouTube egr cooler by nutz and bolts. It's a great easy to understand walk through how to diy. I've cleaned mine with oxyclean and purple power degreaser. I cleaned mine at 70k was pretty clogged now at 99k still runs like brand new.
     
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  12. mjoo

    mjoo Senior Member

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    Burning oil through stuck piston rings produces similar results as burning oil through PCV.

    Actually, you're burning 1q engine oil every 2k miles somehow with OCC. That's probably worse than burning 1q of PCV liquids since some of that liquid is water and gasoline.

    Pixel XL ?
     
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  13. bikes4u

    bikes4u Member

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    I did that about 50k miles ago about 1 year ago and installed OCC. Now needs cleaning again so for me at least the OCC didn't do much for keeping the EGR clean. I will say that my car has had just a few rumble starts since the OCC but they were not severe like without the OCC so that benefit is worth it

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  14. bikes4u

    bikes4u Member

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    Ok I see.... So the OCC doesn't keep the EGR clean. I guess I'll just have to clean it every 50k then. Thanks for explaining that

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  15. msg4life

    msg4life Member

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    It depends.. Remember water is not compressible or combustible, so that's where I believe headgasket failure happens on the prius. Water keeps getting sucked into the cylinder and that knocking start up noise perfect example of that. Oil and gas vapor ignites. Sure leaves behind carbon but I guess pick your poison.
     
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  16. mjoo

    mjoo Senior Member

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    Right, my point being that in an oil burning engine that has an OCC - carbon buildup in the cylinders is still occurring. Probably best to correct the oil burning also. Correcting oil burning should help lesson the rate of EGR build up. Carbon buildup may be causing OPs P0302.

    Pixel XL ?
     
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  17. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Did you remove the intake manifold at that time to clean the EGR passages?

    Yes.
     
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  18. The Critic

    The Critic Resident Critic

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    Diagnosing a single cylinder misfire requires you to focus on causes which can affect a single cylinder only.

    If you do not have coolant loss, it is unlikely that it is a head gasket issue. Your compression test confirms that compression is good and even.

    A valve sealing issue is most likely to show up when cold, but it is not impossible for it to show up under other circumstances. A leakdown test would be your best way to confirm.

    The EGR system will more than one cylinder, not just one. But I suppose that if one of the channels in the manifold was clogged it could affect only one cylinder.

    Edit: did not read the original post.
     
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  19. bikes4u

    bikes4u Member

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    I dont remember, seems like I cleaned everything but I'm not entirely sure. When I took it apart the other day the 3/8in pipe was at least 1/2 plugged so I suspect everything is gummed up again. I unplugged the electrical plug to the EGR temporarily and it runs smooth as butter now. I will clean out the EGR system when I get time.
     
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