EGR delete or disabling through software

Discussion in 'Gen 3 Prius Main Forum' started by Juntuner, Apr 30, 2021.

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  1. Mendel Leisk

    Mendel Leisk Underfoot

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    • IIRC @Ragingfit disconnected his EGR, and down the road (albeit 50k) it had crankshaft failure. Very interesting 4th gen to Prius v transplant series here. It also had runaway oil consumption. Basically same orig engine as 3rd gen.
    • No idea how I got bullet points, ah well…

     
  2. rjparker

    rjparker Tu Humilde Sirviente

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    You will never get a definitive how to on an egr delete here. Or even solid evidence that an egr system that is clogged causes head gasket leaks.

    Gen2 Prius from 2004-2009 have no egr so its more than possible to operate cleanly without an egr. In the US they put a high value catalytic converter on them to clean the pollutants. Gen3 added an egr and reduced the precious metals in the cat.

    Gen3 has a near crisis in head gaskets, gen2 without an egr does not, while a gen4 with a total reengineered engine and egr system also does not suffer head gasket issues. I point at the oil burning in the gen3s, acknowledged by Toyota, as the source of blowby and carbon that causes head gasket leaks.

    What is the most likely root cause of blowby and carbon, the acknowledged ring problems or the Priuschat inspired clogged egr theory?

    Best advice - keep the rings clear when they are young before clogged arteries takes down the machine later. Toyota mechanics are often suggesting 3k-5k oil changes, early and often. Or if the heart of the engine is shot, perform open heart surgery with new parts and then keep it that way.
     
    #62 rjparker, Nov 1, 2021
    Last edited: Nov 1, 2021
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  3. Paladain55

    Paladain55 Junior Member

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    Could be a combination of both. But we agree. Oil intervals over 5k and wimpy piston rings are not a good combo. Especially when egr is also involved. I think Toyota dropped the ball swapping the oil change interval on the gen 3 prius to 10k from 5k shortly after release.
     
  4. ASRDogman

    ASRDogman Senior Member

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    I wonder if running and engine cleaner through every 10-20,000 miles would help the rings???
     
  5. rjparker

    rjparker Tu Humilde Sirviente

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    Some mechanics like a flush on long intervals right before an oil change.
     
  6. OptimusPriustus

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    I browsed this thread and decided to turn my coat. Prius gonna get cooler+egr+im cleaning in two weeks:) Also new pcv valve. MPG is about 44 and i think it’s on the high side. Interesting to see if it change for better. Down them pumping losses(y)
     
  7. Tombukt2

    Tombukt2 Senior Member

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    Seems to me the JDN engine and transmission is the way to go 60 65K on it never touched by anybody in the states got a long time to ride that baby out to you blow it up if you're any kind of normal driver I also saw where there is a 2 l available somewhere to swap into these things I have to research more I don't even remember the engine designation but it was listed on one of the JDM sites is fitting the Prius with the two ZZFXE or the 1.8 which I despise

    SM-A715F ?
     
  8. Tombukt2

    Tombukt2 Senior Member

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    Could water injection be a thing on these over EGR 'D engines . I saw a pic of a gen 3 with a head off scared the crap out of me I was unbelievable how bad the buildup was it was incredible like cylinders were full the under the side of the head was just almost flat no place to see valves or anything was incredible I know in the old days we used to pour water down the carburetor holding the thing at 4,000 RPMs and watched the spit balls of carbon come flying out the back and smacking to the shop wall that was a long time ago one of these little engines might blow up doing that

    SM-A715F ?
     
  9. ASRDogman

    ASRDogman Senior Member

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    Sorry, but I do no understand what you are writing.
    It doesn't make any sense to me, and it all blends together.
    Please use some periouds, commans... etc.

    It's best to read what you type before sending it.

    Not trying to be a pain, I do not understand your comments... :(

     
  10. xliderider

    xliderider Senior Member

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  11. Rodbuilder

    Rodbuilder New Member

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    The "purpose" of any egr syatem is NOT to increase mileage. The sole purpose of it is to reduce emisssions.

    The fact that it increases mileage is caused from the introducction of unburt combustion gasses which are given a 2nd chance of burning.

    While the egr isnt an afterburner it gives the engine a chance to be one!! is that a good thing? Not if it requires maintenance and not if it can cause future harm to something else.
     
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  12. ChapmanF

    ChapmanF Senior Member

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    You are mistaken on all of those points: (1) EGR in a spark-ignited engine does not have a "sole" purpose, but multiple ones; (2) improving mileage is one of them; (3) reburning of unburnt gases isn't the main way it increases mileage.

    Two of its more important contributions to mileage are: raising the knock threshold, so ignition timing can be further advanced, and allowing the use of wider throttle openings at mid loads to reduce pumping losses.
     
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  13. ToyXW

    ToyXW Member

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    Increasing mileage reduces emissions too.

    Common misconception. EGR is not meant to burn unburnt combustion gasses (CO & HC). That's the job of the catalytic converter:

    [​IMG]


    EGR was originally designed to lower combustion temperatures to reduce NOx emissions by introducing what is nearly inert gas into the combustion chamber. Any unburnt hydrocarbons are just a bonus. See How Exhaust Gas Recirculation (EGR) system works

    In the gen 3 & gen 4 Prius Toyota also uses it to decrease pumping losses at low loads (what would normally be part throttle). Essentially, Toyota electronically holds the throttle body open but uses EGR to "throttle" the engine down to the power demanded by the driver's accelerator pedal. Toyota also uses the EGR "cooler" more like a heat exchanger - both to cool EGR and to quickly warm up coolant. A more rapid warm-up reduces cold start emissions and fuel consumption:

    https://publications.anl.gov/anlpubs/2010/06/67317.pdf


    The all-new 2010 Toyota Prius: Ready to welcome more Canadians to the sustainable transportation revolution | Toyota Canada
     
    #73 ToyXW, Apr 1, 2022
    Last edited: Apr 1, 2022
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  14. ChapmanF

    ChapmanF Senior Member

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    Although already mentioned earlier in this thread (way back in post #10), after four pages it's probably worth mentioning again: the EGR system and the Exhaust Heat Recirculation System are two different systems. The EHRS is the one that's used to achieve more rapid warmup.

    The EHRS heat exchanger is down under the car, in the exhaust after the second cat converter. It is completely separate from the EGR cooler.

    [​IMG]
     
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  15. ToyXW

    ToyXW Member

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    Thanks for the correction
     
  16. Danny13pruisc3

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    Sooo... maybe a Brazilian ECU flash? or buy an ECU from brazil?
     
  17. Paladain55

    Paladain55 Junior Member

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    I will have to do a GoPro video of driving around with and without EGR. You can tell the engine is doing its best to adjust the load a lot without EGR. Doesn't do peak load 99% of the time like before. Real-world results though, considering I do a lot of pulse n glide in town and on hills (2100ish rpm) but still do a lot of steady-state cruising at 44 mph (like 1250 rpm), seems like I probably am losing 1-2 mpg with the "EGR delete".
    I guess to be more clear the engine used to drive around with the throttle body just about wide open the entire rpm range regardless of rpm if I remember correctly, which agrees with the reducing pumping losses theory.
    *We are still 50mpg+ with the EGR delete on the 2010 Prius
     
    #77 Paladain55, Apr 13, 2022
    Last edited: Apr 13, 2022
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  18. Mendel Leisk

    Mendel Leisk Underfoot

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    Still, Toyota engineers designed that engine to run with properly functioning (not carbon-clogged or disabled). I think they take advantage of the quenching effect of exhaust gas being introduced, push the engine a little harder. That fall-off of peak load you mention is maybe the car's electronics detecting the EGR not working, making a change to (hopefully) protect the engine.

    My 2 cents: clean it periodically, and let it do it's thing.
     
  19. Paladain55

    Paladain55 Junior Member

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    quenching effect of exhaust gas being introduced

    Can you explain this

    _________________________________________________________________

    My understanding is that they use a lot of EGR introduction down low and taper through the curve until the higher RPMs to reduce the output in J/*CA. Meaning they can use the EGR valve as the throttle for the engine and keep the throttle body open like they do. In fluid and thermal systems we learned a bit about how much horsepower (or kW) you can lose with each butterfly valve you use in a system when it is open at certain percents. Takes a lot of power to overcome the inefficiencies of a butterfly valve but they are very good as slowing things down. ~90% open is around peak efficiency of the throttle body.

    Of course you get some heat too but minimal improvement especially after warmup. I suspect running like it does now I have a BSFC curve closer to a gen 2 now than a gen 3.
     
  20. Mendel Leisk

    Mendel Leisk Underfoot

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    Exhaust gasses are harder to ignite.
     
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