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EGR percentage readings

Discussion in 'Gen 3 Prius Main Forum' started by Orionbuddy, Apr 16, 2019.

  1. Orionbuddy

    Orionbuddy Junior Member

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    I have a fairly cheap OBDII scanner and was monitoring it on a test drive today. My EGR percentage reading was all over the place from 61% to 0%. I understand that the max EGR percentage should be 21% on a 2011 Prius. Are the readings just the result of a poor scanner or (more likely) a poor operator (me)? Can you tell anything about the status of the EGR system from these readings?

    Thanks,
    James
     
    #1 Orionbuddy, Apr 16, 2019
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  2. Raytheeagle

    Raytheeagle Senior Member

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    How many miles on your Prius?
     
    #2 Raytheeagle, Apr 16, 2019
  3. Orionbuddy

    Orionbuddy Junior Member

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    Sorry it has 165,000 miles. No real problems though I have seen a 2-3 mpg decrease in fuel efficiency the last several months. The cause of the loss of mpg is what I am trying to figure out.

    Thanks,
    James
     
    #3 Orionbuddy, Apr 17, 2019
  4. Raytheeagle

    Raytheeagle Senior Member

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    You’re getting restricted in the egr circuit:cool:.

    Time for the complete egr circuit cleanse ;).

    Loss of mpg can be other things (tire pressure, weather, etc), but the egr circuit restriction I found to drop my mpg about 3-4 mpg. I could see the change over time as I keep an eye on it:).

    Good luck and keep us posted (y).
     
    #4 Raytheeagle, Apr 18, 2019
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Start by checking the EGR pipe, it's easiest to access and will give you some idea of the rest. See @NutzAboutBolts video on this, and the whole circuit cleaning too, at top of 3rd gen maintenance forum. There's some good threads too: just google priuschat and EGR.
     
    #5 Mendel Leisk, Apr 18, 2019
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  6. Orionbuddy

    Orionbuddy Junior Member

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    The EGR pipe was pretty dirty though far from fully plugged up. I will tackle the full EGR system cleaning as soon as I get time. I need to do my mom's car also. I think I will buy a new EGR cooler and install it on one vehicle and clean the old one then install it on the second prius so there is little downtime.

    Thanks, James
     
    #6 Orionbuddy, Apr 18, 2019
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    New are around $250 IIRC, and used around $80. Yeah you have to clean, but...
     
    #7 Mendel Leisk, Apr 18, 2019
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  8. ASRDogman

    ASRDogman Senior Member

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    You can check eBay for egr coolers. You may also want to do a search for them and find different
    junk yards that may have them.
     
    #8 ASRDogman, Apr 18, 2019
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  9. mikey_t

    mikey_t Active Member

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    The pipe isn't likely to be fully plugged, but if it has significant carbon then the cooler likely is.
     
    #9 mikey_t, Apr 18, 2019
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Good point. The passageways in the cooler are very constricted. An eighth inch build-up on the pipe just constricts it a bit. The same amount of build in the cooler would be pretty bad.
     
    #10 Mendel Leisk, Apr 18, 2019
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  11. Grit

    Grit Senior Member

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    Neat, which app is that?
     
    #11 Grit, Apr 18, 2019
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  12. Orionbuddy

    Orionbuddy Junior Member

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    My scanner is the Ancel 410 I believe. I unfortunately don't know much about scanners. I am assuming that EGR_PER is EGR percent but you know how that goes.

    James
     
    #12 Orionbuddy, Apr 21, 2019
  13. spiralhelix

    spiralhelix Active Member

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    Dang, i just bought a different scanner that doesn't have the EGR monitoring! I wish i had seen this post. But plugging the 410 into the tracking app, it looks like Amazon does Lightening deals on this scanner quite a bit bringing the price down to ~$32. They don't last long and usually in the middle of the night, but at least it's a heads up.

    edit: I just checked the scanner i purchased (the autel al319) and it also has live stream with EGR_PER. Took a quick drive around the block and it stayed at 0.0%. I'll do another test on my drive home and see if that changes.
     
    #13 spiralhelix, Apr 24, 2019
    Last edited: Apr 24, 2019
  14. spiralhelix

    spiralhelix Active Member

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    Here are my readouts from my drive home. The % did fluctuate depending on accelerating/decelerating but never got above 68%. When the ICE shut off, the egr % instantly dropped to zero. My clean EGR has a little over 4k miles on it, so doubtful it is clogged.

    65 mph 5 min after starting.
    IMG_2956.jpeg

    65 mph 20 min at speed
    IMG_2957.jpeg

    80 mph 30 min at speed
    IMG_2958.jpeg
     
    #14 spiralhelix, Apr 25, 2019
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  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Some info from the Repair Manual, mostly using Techstream, over my head:
     

    Attached Files:

    #15 Mendel Leisk, Apr 25, 2019
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