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Semi completed egr service

Discussion in 'Gen 3 Prius Fuel Economy' started by Norryboy1a, Jul 23, 2021.

  1. Norryboy1a

    Norryboy1a Junior Member

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    It was my best intention to finally change the EGR cooler and clean out the connecting pipe to the intake manifold. I disassembled the connecting pipe and thought that maybe I could just start the process with cleaning that. Then work my way back to replacing just the cooler without changing or removing the EGR. The pipe was really bad. Cleaned it with crc and squirted a lot up into the egr output. Then stuck a wire brush up it the clean it more. Came out really caked with carbon. Tried to get to the cooler, but ran out of steam. the results with just that little cleaning made a vast improvement in performance. I can only imagine how well it will run once, somehow, I can replace the cooler.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Did you happen to collect any EGR flow monitor values from before or after the cleaning?
     
  3. Norryboy1a

    Norryboy1a Junior Member

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    Well, that would have been a good idea if I knew how to do that.
     
  4. Norryboy1a

    Norryboy1a Junior Member

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    I do have a very basic scanner for basic resets and troubleshooting. But, I guess I should invest in a tech stream.
     
  5. ChapmanF

    ChapmanF Senior Member

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    On that EGR monitor thread there are examples of people using other OBD-II scanners, smartphone apps, or what-not, that also can retrieve the EGR flow stats; all that's needed is a tool that can issue "mode 6" monitor status queries. For a tool that hasn't got this knowledge built in, the EGR flow monitor result is monitor ID 31 (hex), test ID bd (also hex).
     
  6. Norryboy1a

    Norryboy1a Junior Member

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  7. Norryboy1a

    Norryboy1a Junior Member

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    That is helpful. I have a friend that has one that’s he uses. Thanks. Maybe I can tackle the full job later. I’m at least hoping that this mini job will buy me some time w/r to replacing the EGR cooler.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Have you done the small passages in the intake manifold yet?

    That's, in my opinion, the easiest subtask and also the one most worth doing, because the single MAP sensor used for the feedback control of EGR isn't able to detect different levels of occlusion in those four ports.
     
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Equals: doesn’t know some might be more clogged than others.

    Cyl 1 passage (nearest passenger end) seems to invariable clog up fastest.

    Have you got the wiper and cowl off? It makes cooler access (for removal) much easier.
     
  10. ChapmanF

    ChapmanF Senior Member

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    In much the same way that taking your shirt off makes a DIY splenectomy much easier.
     
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  11. Norryboy1a

    Norryboy1a Junior Member

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    I thought that just maybe if I move all the wiring harnesses out of the way and use a flexible type of ratchet wrench, I might be able to squeeze in there to loosen the exhaust nuts. After clamping the hoses. I thought that I might be to change the cooler by not removing the egr valve itself. And just clean it by injecting crc into the intake egr port directly. And by using the brush. Then replacing the cooler.
     
  12. Norryboy1a

    Norryboy1a Junior Member

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    I also thought that I would tackle the Intake manifold later.
     
  13. ChapmanF

    ChapmanF Senior Member

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    That tends to be the general order of things anyway. Of the nuts attaching the valve to the cooler, one becomes pretty inaccessible once it's all been secured to the cylinder head. If you ever want to just replace the EGR valve for some reason, you may find it necessary to loosen, at least, the cooler mountings.

    Once the cooler and valve have been removed together, removing the valve from the cooler is easy-peasy.
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Wouldn’t mind being proved wrong, but I think full removal is ultimately easier. And cleaning is way easier, cooler likely fully cleanable, with patience. I found oxi-clean soaks good. Check out “bad flywheel” link in my sig, some tips on avoiding coolant spill.
     
  15. ChapmanF

    ChapmanF Senior Member

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    Or just schedule for when you want a coolant change anyway, and spill it on purpose.
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    I don't think I spilled a drop, using method in the "bad flywheel" link. Clamping the coolant hoses on the cooler is an absurd excercise: you clamp them, pull them off, and the coolant all spills out of the cooler, which is above. A preemptive drain of 2 quarts drops the level below the system, then just pour back into reservoir when done. Helps to have coolant vent open when refilling (2010~2011), and for later years (which nix the vent) disconnect a topmost hose will accomplish same thing. And NO need to disconnect throttle body coolant lines.