2010 Prius - Regardless of speed/Vehicle vibrates inconsistently

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Pepper Anderson, May 5, 2021.

  1. Pepper Anderson

    Pepper Anderson New Member

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    Symptom: Vehicle vibrates at any speed, from a stop, cruise on or not; inconsistently.
    Have replaced spark plugs and engine coil on all (4) cylinders no change to vibration

    Code is P0304 - however the vibration was occurring long before Code showed up. Last mechanic said the vibration is due to misfiring on cylinder 4 - is that possible? Their solution was a new engine $8k-$9k
     
  2. bisco

    bisco cookie crumbler

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    welcome!
    are you losing any coolant?
     
  3. tankyuong

    tankyuong Senior Member

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    Mine did that before throwing a rod
     
  4. Pepper Anderson

    Pepper Anderson New Member

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    No . . . not loosing coolant
     
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    Lots of things could cause a misfire. Bad spark plug or coil, fuel injector, low compression or other engine mechanical fault, partially clogged EGR passages in the intake manifold, etc. If there was a problem that required the engine to be replaced- then I would expect the misfire to be present all of the time.

    Posted via the PriusChat mobile app.
     
  6. Pepper Anderson

    Pepper Anderson New Member

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    ***************************************************************************************************************************

    Additional Information - Compression results
    Cylinder 1 - 3; 110 - 115 PSIG
    Cylinder 4; 90 -100 PSIG

    Observation
    Vibration appears to occur when the Internal combustion engine (ICE) is under load. If you let up on the accelerator or "gun" the accelerator the vibration diminishes.

    Any suggestions?
    Any recommendations on brand or flavor of fuel injectors? Plugs and Coils already replaced
     

    Attached Files:

  7. Mendel Leisk

    Mendel Leisk Underfoot

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    It has been more common (by far) for cylinder one to report misfire. Still of late there’s been a few cyl four reports. Both cases somehow due to imbalanced* rate the EGR passages in the intake manifold clog?

    Low compression could indicate valve not sealing? Or bent piston rod, so TDC is slightly lower? The latter seems to mesh with “vibration”.

    * Tends to be cyl one “wins” the race.

    Oh: how many miles?
     
  8. ChapmanF

    ChapmanF Senior Member

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    The only thing so far established in #6 is that cylinder 4 has slightly lower compression than 1, 2, and 3.

    That result seems to have come from a compression test, not from a leakdown test, so it has not indicated why the compression is lower. (In a traditional compression test, the tech would normally then repeat the test with a dollop of oil spooned into the cylinder, which can at least distinguish a few of the possible causes. If the compression goes up after adding the oil, leakage around piston rings is indicated. If the oil doesn't change anything, the leakage is probably related to the cylinder head, valves, or head gasket. A leakdown test will give more information.

    If the cause of low compression is narrowed to the top end, and if it is further determined to be a head gasket failure and not something else, then speculations about what might have caused that could be in order.
     
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