2010 Prius still shakes after head gasket job and EGR + intake cleaning

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by infinitepub, May 7, 2025.

  1. rjparker

    rjparker Tu Humilde Sirviente

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    There is no direct egr step position status or feedback. But the egr step test uses the map pressure as a good indicator.

    A lot of this assumes your previous egr block test was successful. I would block the flow manually again and drive it 15 minutes in normal mode (not maintenance mode) and verify the engine runs good with a full warmup. If it does not continue to run smooth you have to reevaluate your focus.

    Egr step test with Techstream

    Run the egr step test procedure while watching the map pressure. The engine must be placed in maintenance mode to force continuous running. The procedure wants you to warm up the engine. You will see map pressures at idle changing as you command the egr open using Techstream.

    When the egr is closed at step 0, the map pressure usually reads about 4 psi absolute. As the egr step opens the psi will increase causing idle roughness around step 15-20.

    Later you should be able to watch the map pressure under normal conditions and significantly understand what the egr is doing. Remember, the egr should be closed at idle and low rpms. The egr valve is also closed at wide open throttle.
     
    #41 rjparker, May 24, 2025 at 12:51 AM
    Last edited: May 24, 2025 at 8:26 AM
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  2. rjparker

    rjparker Tu Humilde Sirviente

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    You can check the power and wiring continuity with a meter.

    IMG_8361.jpeg
     
  3. ChapmanF

    ChapmanF Senior Member

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    I'm not sure about using MAP under normal conditions for info on what EGR is doing, because under normal conditions the MAP is so strongly affected by throttle position and engine load that the effect of EGR will be hard to tease out.

    The car does a self-test of its own for EGR, where it uses the MAP reading, but only at moments when the car is decelerating, the throttle is closed, and the engine is spinning without fuel. Under those specific conditions, it is able to interpret the MAP reading as a test for EGR.

    The result from the last time the car ran that self-test can be viewed on any scan tool that can show "mode 6" results.
     
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  4. Ohiggins

    Ohiggins New Member

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    When I was researching EGR cooler cleaning threads, I would swear I saw a post where someone purchased a new EGR valve and had to also have an update flashed on their ECU.

    When I did my cleaning two weeks ago, I purchased a used EGR cooler and valve from eBay. Cleaned the used components and swapped them in my 2013 Prius. Engine at the initial start ran rough and would die after a minute or so.

    Compared the part numbers on the used valve vs the one I removed. Used part number ended in '10', the one I took off the car was the same, but ended in '20'.

    Cleaned the '02' one I had removed and swapped it back into the engine. All was well and the engine ran fine.

    Bad 'old' valve from eBay? Or something not compatible with my newer vehicle / ECU?

    EGR valve from eBay - 25620-37110 (did not work correctly)
    original EGR valve - 25620-37120 (worked when cleaned and reinstalled)
     
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  5. ASRDogman

    ASRDogman Senior Member

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    When you buy something like the egr valve used, you don't really know what you are getting.
    The egr valve may have already been replace with the updated very and the ecu updated.
    Using the older part caused issues....

     
  6. ChapmanF

    ChapmanF Senior Member

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    There was a firmware update mentioned in the same TSB that announced the revised EGR valve.

    "Had to have" may be a little strong. The same firmware update is also mentioned in another TSB from around the same time, involving the intake manifold. If you changed the manifold per that TSB and updated the firmware, you'd have the new firmware and the old EGR valve. If you changed the EGR valve per its TSB and flashed the firmware, you'd have the new firmware and the old manifold. And neither the manifold nor the EGR valve has any kind of feedback where the ECM would know it's got one or the other.

    I think the firmware update just has some miscellaneous tweaks Toyota figured would also be useful if people have the symptoms in either of those TSBs.

    I had the update done in my car without changing the manifold or the EGR valve. The main thing I notice about it is a slightly higher idle RPM when the coolant temperature is below 30℃ or so (maybe it's 35). That's a kind of generic tweak for smoother running when warming up ... in my older cars I'd sometimes do the same thing with my foot.
     
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  7. rjparker

    rjparker Tu Humilde Sirviente

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    By 2013 new Prii came with the updated egr valve. So you took a better design off and replaced it with an older used design.

    However the ecu is not likely to have the latest software as there were changes through 2016.