Need help to identify a plastic contain in right side fender well

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by lsac, Jul 31, 2015.

  1. lsac

    lsac Junior Member

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    Photo below is borrowed to show this plastic container right behind front bumper. Not sure what it is used for. Mine has a broken arm that attaches to the car frame. Your help is much appreciated.
     
    #1 lsac, Jul 31, 2015
    Last edited: Jul 31, 2015
  2. bisco

    bisco cookie crumbler

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    someone else brought this up once, hmm... some kind of baffle or harmonic balancer kind of thingy?
     
  3. vskid3

    vskid3 Active Member

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    Yep, its some sort of resonator chamber for the intake. Its not really necessary, mine has been without one for a year and a half.
     
  4. ChapmanF

    ChapmanF Senior Member

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    This has been a good summer for the number of times the term "Helmholtz resonator" gets used in a forum. :)

    The engine always sucks air in pulses, so there are always pressure waves in an intake. The Helmholtz resonator's job is to make sure the waves tend to increase the intake efficiency (air moving back toward the manifold at about the right time it's next needed) throughout the most important range of engine speeds, rather than being out of phase and decreasing it. That also tends to keep noise down (most of the wave energy is going into the engine rather than coming out the intake bell).

    -Chap
     
    RRxing and bisco like this.
  5. lsac

    lsac Junior Member

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    Great write up Chap. Thanks much. I have searched up all service PDFs and cannot find a clue. My resonator is dangling. I guess I will use a metal strap to keep it in place.
     
  6. lsac

    lsac Junior Member

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    Nothing.
     
    #6 lsac, Jul 31, 2015
    Last edited: Jul 31, 2015
  7. ChapmanF

    ChapmanF Senior Member

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    Hmm, if it's dangling, you might check carefully whether its neck is still connected to the intake duct. Having it disconnected there magically changes it from a Helmholtz resonator into a random plastic jug.

    -Chap
     
  8. 69shovlhed

    69shovlhed Surly tree hugger

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    I think the ICE sounds better with it off.
     
  9. bisco

    bisco cookie crumbler

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    can't find the part on toyota on line oem parts?
     
  10. valde3

    valde3 Senior Member

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  11. lsac

    lsac Junior Member

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    Agree. The jug is pretty solid so I can just tap screws right into it to attach the metal strap.
     
  12. lsac

    lsac Junior Member

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  13. ChapmanF

    ChapmanF Senior Member

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    I was thinking more about making sure the narrow neck at the top of the jug is still sealed into the intake duct, and there aren't any breaks anywhere that would make it leaky. Physics-wise, adding any new openings makes it a different resonator, possibly a poor match for the ICE.

    I know it can seem weird to think that an empty jug hung off the intake is making any difference at all. I had a similar feeling once in a physics lab in college and I wrote a comment in the margin of my lab report, wondering why something made a difference when it didn't seem like it should. It came back with a note from the prof: "Are you planning to take Waves before you graduate? If not, You'll Never Know!"

    Turned out I never did take Waves there, but eventually figured some of it out anyway ... what, did he think I'd never use a library? :)

    -Chap
     
  14. WFBowen

    WFBowen Junior Member

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    I think that the Atkinson-cycle engines used in the Prius tend to inherently produce more intake noise vs the Otto-cycle engines. Whatever the reason (local market noise standards, quiet passenger compartment, etc.) Toyota seems to have devoted lots of attention, as well as valuable under-the-hood space to this situation.
    Bill
     
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