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How important is the charcoal filter? Clogged at 330k+ miles?

Discussion in 'Gen 3 Prius Main Forum' started by Priipriii, Aug 19, 2022.

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  1. Priipriii

    Priipriii Member

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    Not many people might know, but charcoal filter is that thing above the air filter that no one talks about.

    I find it very ironic that everyone loves to claim "CHANGE THE AIR FILTER, it increases MPG and performance! Dirty ones do not allow engine to breathe." I totally agree, which is why I'm asking this very important question. At 300k miles, it is SURELY going to be clogged, even if not from fumes, definitely from carbon from EGR backflowing. If gasoline fumes can, one would think the carbon that clogs the EGR tube will backflow and clog the charcoal filter the same way.

    And how much emission control is it really saving, has anyone actually thought about it? From what i've researched, it is strictly for when the engine is turned off and the gasoline vapors flow back the air intake. What is that, like .002% of all emissions? Ridiculous! I imagine in a brand new prius you wont noticed much of a different with filter or without, but my 300k is sluggish to accelerate, and the mpg are poor. I was considering swapping to a cold air intake, but after learning about the charcoal filter, I think i found the performance goblin.

    I am going to conduct my own test using Torque pro app and seeing how it affects overall speed at certain throttle positions with and without the the filter. I will post back when I finish.
     
    #1 Priipriii, Aug 19, 2022
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  2. ChapmanF

    ChapmanF Senior Member

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    Hardly plausible. Even if you imagine EGR soot backflowing into the intake manifold some, here you're imagining it swimming up through the throttle body and the intake elbows and resonator, all against the steady stream of air being drawn in.

    Easy enough to check, though: pop that top elbow off and post photos of whatever signs of soot clogging you find in the airbox lid.
     
    #2 ChapmanF, Aug 19, 2022
  3. scedacity

    scedacity New Member

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    The charcoal trap for the evap control absorbs about a tank-full of gasoline vapors each time you fill. That's not inconsequential and is a big contribution to California's smog control measures. It shouldn't "clog", but if you feel the need to replace it, it should be one of the cheaper parts to replace.
     
    #3 scedacity, Aug 20, 2022
  4. Priipriii

    Priipriii Member

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    Are you talking about the filter at the gas cap?? Since you said each time I fill, is implying the gas cap.

    But if you are referring to the filter above the air filter, you say a tank full of gasoline vapors, in gas form, is basically nothing. Considering the first 3 seconds of the engine running, the engine already sucks in a tank full of oxygen.
     
    #4 Priipriii, Aug 23, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    I think scedacity was referring to the charcoal canister mounted under the car, amidships near the fuel tank. Different from the small charcoal filter in the airbox lid.
     
    #5 ChapmanF, Aug 23, 2022
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  6. Priipriii

    Priipriii Member

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    I don't care about the filter under the cap, as that does nothing for my vehicles performance or gas mileage. I am aware of its existence, but it is not what I was asking about lol.
     
    #6 Priipriii, Aug 23, 2022
  7. ChapmanF

    ChapmanF Senior Member

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    Nobody's talking about one under the gas cap.

    You were talking about the one in the airbox lid, and scedacity thought you meant the one under the car amidships.
     
    #7 ChapmanF, Aug 23, 2022
  8. Priipriii

    Priipriii Member

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    Did not know there is another filter...

    Either way, that one is not taking my performance away either, so it is irrelevent.
     
    #8 Priipriii, Aug 23, 2022
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