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Changed 2009 prius pcv valve after 96k miles

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by epoch_time, Feb 2, 2018.

  1. epoch_time

    epoch_time Active Member

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    Well I finally installed new pcv valve that I purchased 6 years ago (part number 12204-21011).
    I had put off installation due to the excessive removal of parts for access to pcv valve.
    I removed the airfilter housing, relay box, loosened cable harness, disconnected injectors and spark coils.
    Pulling loosened wire harness forward allowed access to pcv valve. There are some good youtube videos showing how to do it without removing cowling and window wipers.
    I had to use a deep impact socket and a pipe wrench to turn the socket to remove pvc valve.

    Anyway the pcv valve looked perfect after 96k miles. Probably because I've alway change/used mobile 1 5-30w extended performance synthetic oil at 4-5k mile intervals. I've owned the prius since new with only 8 miles on it. So I know the pcv valve was never changed till now.

    The Old pcv valve rattles like the new one and seems to be good. With the new valve installed the prius runs much better.
    Less misfires (displayed with torque apk). No more pinging. Smother gas engine starts and stops. More acceleration with less gas pedal depression. No more hesitation on acceleration.

    I thought my prius was running great before I changed the pcv valve getting 50+ miles per gallon.
    Now it runs even better.

    The old valve blocks flow toward engine and allows flow away from engine. I suspect a new valve might block both directions depending on internal spring tension within pcv valve. I went to toyota dealer to purchase another new pcv valve so I could check if it allows flow away from engine.

    Toyota says there are two part numbers for pvc valve for 2009 prius and they are out of stock on both.
    Toyota wanted to know my vin number to provide the right pcv valve.
    The two part numbers are 12204-21011 and 12204-21012. Dealer doesn't know why or what the difference is. My early model 2009 purchased in december 2008 uses 12204-21011 pcv valve.
     
  2. JC91006

    JC91006 Senior Member

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    You're experiencing the placebo effect
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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  4. SFO

    SFO Senior Member

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    Would be great if you had a vacuum pump or pressure pump and could test with and report your findings on both the New and Old valves.


    2009 was the year Toyota switched from Gen2 to Gen3.
     
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Not sure what you're saying. OP probably knows what gen he has: model year 2009 gen 2, purchased December 2008?
     
  6. SFO

    SFO Senior Member

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    Was saying this could be the reason for the differing part number(s) and or why the parts jockey wanted to go by the VIN.

    "Third generation (XW30; 2009–2015) - Toyota debuted the new Prius (2010 US model year) at the January 2009 North American International Auto Show, and sales began in Japan on 18 May 2009."
     
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  7. Prodigyplace

    Prodigyplace Senior Member

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    I remember reading from one of our mechanic users here that you cannot properly test the valve by shaking it.
    They may be actually experiencing improved economy.
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Does a failing PCV valve cause a drop in mpg? Not sure. To further complicate matters, it can fail open, or closed? I'd suspect there was nothing wrong with OP's, but it doesn't hurt, preventative maintenance.
     
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  9. SFO

    SFO Senior Member

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    Not sure the OP has realized any gains in MPG, or reported any losses.

    Would be interesting to know the OP's ratio of city/highway driving and at what average speed(s), not to mention any previous oil usage or lack thereof now that the PCV is new again.
     
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  10. TMR-JWAP

    TMR-JWAP Senior Member

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    I suspect a new valve might block both directions depending on internal spring tension within pcv valve.

    I don't understand this.......wouldn't that be called a plug?

    Positive Crankcase Ventilation = any pressure in the engine internal volume due to compression/combustion gases leaking past piston rings vents to the low pressure (vacuum) of the intake system and gets recycled back to the combustion cycle. In the big scheme of things, a vacuum in the crankcase is most efficient as it provides less resistance to crank/rod/piston motion..
     
  11. epoch_time

    epoch_time Active Member

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    1200 miles later after changing pvc valve and getting approximately 15% increase in ice output.

    I'm trying to understand why the substantial increase in power to the point of being overly concerned.

    I Thought my prius was running perfect before changing orignal pvc valve. Its now better than perfect!!!!
    I am now worried that this large increase in ice power is adding much more wear and tear on my internal combustion engine. I have accually lost about 2mpg with the new pvc valve and increased the ice output.

    I have tried to come up with many theories for the increase in ice power (excluding PVC) including but not limited to;

    A; Fresh electrical connections to the spark coils and to the injector coils (after disconnecting and reconnecting them).
    B; Cleaned some caked up dirt off the outside of the mass air flow module (orignal maf now has 97k miles).
    C; Blew out Small amount of dirt from allready clean looking air filter.

    If you change your PVC valve I would add a drop of oil from your dipstick into the bottom of new PVC valve (and shake).
    I didn't do this. But occured to me that the pvc internal piston/slug could use some preliminary oil lubrication to make it last longer.. Its probably this piston/slug that wears out.

    Being overly concerned with increased power, slight loss in mpg (2Mpg), additional engine wear. I decided to reboot all the computers/ecu's disconnect 12v battery) and let new fuel trims to be learned.

    This reset/reboot of ecu's was about 300 miles ago and there is no difference still to much performance.

    I guess the hessitations (and misfires) of the ice on the old PVC (which appeared to be in perfect condition) was a gas saver hehe.

    My prius is driven mostly city miles, Doesn't burn any oil yet (might start burning oil now that engine is putting out more power). I was seeing 30 to 50 misfires per drive as seen on torque apk (couldn't fill it at all). Now I see one to three misfires on the torque apk (this is with orignal spark plugs 97kmiles old).

    Summary the prius pvc valve is a precision part that does wear. lubricate (lightly) before installation!
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    How are you measuring engine "output"? Seat-of-pants feel when accelerating?.
     
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  13. epoch_time

    epoch_time Active Member

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    Yes seat-of-pants feeling
     
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