Techstream EGR Valve Blockage Data

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by jas8908, May 3, 2019.

  1. Mendel Leisk

    Mendel Leisk Sand Pounder

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    @ChapmanF and @burebista how many miles do you have? Just wondering how long it takes.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Looks like I posted this result last 22 December. That was about 154,000, um, international customary miles.

    [​IMG]

    So if I remember to pull it again this 22 December, that will be a year. If it has dropped to 0.250, say, I'll start saving pennies faster. If it still says 0.251, I'll figure maybe it changes too slowly to tell me much over a year's time. If it says, say, 0.252, I'll say there's too much test variation to infer a dropping rate over such a short time scale.

    Looking at burebista's result, it looks like this might be another graded-on-a-curve test where the min value changes. That adds some extra murk.

    It is another one of these tests the ECM sneaks in during normal driving. It will deliberately undershoot the proper fuel injection volume for some seconds, making a lean mixture with unreacted oxygen that gets stored in the cat, and then deliberately overshoot the injection volume and see how long it takes for the (downstream) O₂ sensor to show the oxygen level low, which only happens after the O₂ stored in the cat is used up, so the longer it takes, the better.
     
    #162 ChapmanF, Oct 13, 2021
    Last edited: Oct 13, 2021
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  3. burebista

    burebista Member

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    @Mendel Leisk 316k km (almost 200k miles)
    @ChapmanF That minimum value doesn't change. It's carved in stone. :)
    Always 0.2196 (I have a screenshot from July when I saw the lowest value for EGR monitor bank).
    Screenshot_20210727_071940_com.ovz.carscanner.jpg
    But that reading value changes almost daily. Usually is 0.22xxxx but I saw it once 0.220515 and once 0.24xxxx.

    So if I understand it right, it's about catalytic converter and I can't do anything to save it's life. :(
     
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  4. ChapmanF

    ChapmanF Senior Member

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    In my screenshot it's 0.249, so nyeah. :)
     
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  5. burebista

    burebista Member

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    Yeah, but you have an US Prius, mine is an EU Prius. :D
     
  6. Mendel Leisk

    Mendel Leisk Sand Pounder

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    A thought about EGR cooler carbon blockage: beside air-flow reduction, it's been mentioned here, that carbon-coated radiator plates will be less effective at cooling. How much of a factor might that be?
     
  7. ChapmanF

    ChapmanF Senior Member

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    I don't know. Have you thought of a way to look it up or find out?
     
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