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Moisture in Intake Manifold, causing frozen throttle body

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Pil, Jan 29, 2020.

  1. Pil

    Pil Junior Member

    Joined:
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    Location:
    Fairbanks, Alaska
    Vehicle:
    2013 Prius
    Model:
    Four
    I live in Fairbanks, Alaska and its been seriously cold here (-30 to -40 F). Usually the Prius is a real cold-weather champ, but a couple weeks ago I went to turn on the car-- the engine fired up, immediately shut down and the car displayed the dreaded "Check Hybrid System" indicator. I repeated the ignition with similar results.

    It was towed to the dealership, who diagnosed this problem: “Moisture condensing in the intake manifold caused cylinder misfire and caused the throttle to stick. A revised intake manifold is available to reduce, hopefully eliminate the problem. DTC’s P0300 multiple misfire and P0A0F failure to start & P2111 throttle stuck open. Thawing out vehicle restored normal operation. Intake manifold has a lot of moisture in it.”

    The dealership wants to install a "revised" intake manifold for $900. I've done extensive research online and have found very few other examples where an intake manifold moisture issue is causing a throttle body to freeze. The intake manifold suggested is part # 1712037054.

    For background: I have a block heater and I plug the car in for 2-3 hours (if its below 20 degrees F) before using.

    A few questions:

    A) Doesn't my Prius already have this "revised" intake manifold (since its a 2013, and the "revised" design was released in 2012?) Where would I find out the part number of my OEM intake manifold?

    B) Do I really need this revised manifold to solve my problem?

    B) Assuming I decide to forego this expensive and potentially unnecessary repair, how should I prevent moisture from building up in my Intake manifold? My suspicion is:
    --Avoid shorter trips-- turn the car on and let it fully warm up before turning the ICE off
    --Ensure the engine has been plugged in at least 2 hours in cold temperatures
    --A friend of mine suggested putting Isopropyl alcohol in the gas tank to reduce water content. I've done some internet research but am quite skeptical-- it seems a product like HEET would be more effective.

    C) This is my sole automobile and I use it often for wilderness adventures in the Alaskan Interior. It is usually exceptionally reliable but with this potentially chronic issue I'm worried. This weekend I'll be 2 hours away from Fairbanks and leaving the car out for two nights in -20 conditions. I am worried about returning to a car with a frozen TB. I'll have friends cars there to help warm mine up in case of any issue (or if I need a jump). How would you deal with this issue if it repeated itself and you were off the grid?
     
    #1 Pil, Jan 29, 2020
  2. wheezyglider

    wheezyglider Active Member

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    I have possibly some further info, if not final answers.

    The intake manifold part number is stamped on the outside, upper right-ish over the right-most cylinder intake. You can get at least a peek between the fuel rail and the air box without even removing anything.

    When I did my EGR path cleanout I decided to update my 2010 to the latest IM, and somehow ended up with a cold-weather version that has a wire grid insert at the throttle body. Read this post and a few of the following ones for pictures, part numbers, and TSB numbers. Upshot is I ordered IM 17120-37091 and got 17120-37054 with the pictured wire grid insert. I never found out whether all 17120-37054 include the grid, but I kind of doubt it.

    BTW these can be bought for around $300 and installing them yourself is maybe 2 hours work tops, I think I could do it now in under 30m. The NutzAboutBolts video on cleaning the IM shows you everything you need to R&R. (And no need to disconnect any coolant lines.)

    Best of luck in the frozen north!
     
    #2 wheezyglider, Jan 29, 2020
    SFO likes this.
  3. Ed Beaty

    Ed Beaty Active Member

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    "...it seems a product like HEET would be more effective."

    HEET IS isopropyl alcohol. And HEET would have little or no effect on your problem anyway, as it's intended to keep gas lines from freezing by removing water from the fuel; not part of the intake system.
     
    #3 Ed Beaty, Jan 29, 2020
  4. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Oil catch can will help keep moisture out of intake manifold. There's a risk of it freezing as well, though. You want one with good capacity, and maybe mount directly on the engine. There's some possible bracket bolting locations under the intake manifold, the lower row of bolts securing the pcv valve cover plate: one or two of them could do double duty, attach a bracket.

    FWIW, 2015 Intake Manifold (presumably the revised part no?), item #32 here:

    Intake for 2015 Toyota Prius | Toyota Parts

    is $207 USD plus shipping.

    $900 is a little hard to swallow. I could have that intake manifold swapped in an hour, and I'm a lowly duffer. Do the oil catch can while you're at it. There's one video on it, by @NutzAboutBolts, link in thread pinned at top of 3rd gen maintenance forum. He pulls the intake manifold partially off in that video. He does complete removal in another video, specifically for the Intake Manifold cleaning.

    All that said, I wouldn't change the intake manifold, doubt that'll solve the problem. Just remove and clean it, and install oil catch can. Monitor the latter closely, it might freeze up. Thread on catch cans:

    Oil Catch Can, Eliminate that knock! | PriusChat
     
    #4 Mendel Leisk, Jan 29, 2020
    NutzAboutBolts and fuzzy1 like this.
  5. Pil

    Pil Junior Member

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    Thanks for the help.

    Also, I forgot to mention: car is a 2013 with 92k miles.

    I'm definitely not taking my car into the dealership to the get a different IM.

    My plan is to ride out this winter, then do a full IM/ EGR cleaning and maintenance when warmer weather comes. I may or may not upgrade to the "cold weather" intake manifold depending on what else I learn about it.

    Still makes me wonder what I can do now, this winter, to prevent moisture from building up. I'm going to avoid shorter trips. Is there anything else?
     
    #5 Pil, Jan 30, 2020
  6. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Grill block the lower opening 100% might help, not sure. Most are pushing on slitted pipe foam insulation onto the slats, securing it with something. My pref is velcro tape, just easier to install/remove. Where I am I only use 50% block. If it was steadily below freezing I would go to 100%. If temps rise above +10C I pull it all off.

    Best to leave the top opening along, or block 50% at most, since the inverter radiator is behind there.

    You can also push that foam insulation on the two fender seams running down the sides of the fender closing up the hood gap. There I use zip ties, leave that in year 'round.

    The foam tubing insulation I use is 1.5" OD and maybe 7/8" ID, readily available at hardware stores.

    Do you have the block heater?
     
    #6 Mendel Leisk, Jan 31, 2020
  7. dig4dirt

    dig4dirt MoonGlow

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    Is the engine running when you normally shut down or at least sometimes?

    If so, something that may help is to turn off heater on climate control and wait until engine does shut off,
    then turn ignition off.

    Gen3 is known for having some issues when ignition is turned off when engine is still running.

    may be able to search on here about death rattle,
    Not sure if this is related
     
    #7 dig4dirt, Jan 31, 2020
  8. Pil

    Pil Junior Member

    Joined:
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    Location:
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    Vehicle:
    2013 Prius
    Model:
    Four
    I do have a block and oil pan heater. This is especially critical since I park outside and don't have a garage. I also have foam covering my front grill -- I only did this recently and its made a significant difference.

    My current plan is to order the Cold Weather Intake and install this summer. Even though it may not be essential, it strikes me as a decent insurance policy. I'll do some preventative maintenance while I'm in there.

    So far the problem has not happened again. I've been very diligent to keep the car plugged in at least 2 hours when its below -20, and to not shut it off after driving short distances.
     
    #8 Pil, Feb 18, 2020
    Mendel Leisk likes this.
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Throwing a blanket over the hood might help. The block heater warms the whole engine bay slightly, and more insulation could help hold that heat in.
     
    #9 Mendel Leisk, Feb 18, 2020
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