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Poor mileage:: HAVE YOU CLEANED THE MAF SENSOR?

Discussion in 'Gen 3 Prius Fuel Economy' started by Jerry Liebler, Feb 15, 2017.

  1. Jerry Liebler

    Jerry Liebler Member

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    I'm disturbed that, what I found to be the cause of dramatically lower fuel economy in the car I bought to replace my totaled PIP, is rarely mentioned as a cause of poor fuel economy. IMO it should be among the first things looked at whenever poor MPG is observed. The fix is simple and very low cost it should be in the sticky for everyone complaining about fuel economy! HAVE YOU CLEANED THE MAF SENSOR?
     
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  2. AliG2010

    AliG2010 New Member

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    What's MAF and PIP? .
     
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  3. Prodigyplace

    Prodigyplace Senior Member

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  4. 5 Speed

    5 Speed Member

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    I make it practice to clean the MAF every oil change. I know this is OCD but it only takes a few minutes. I am on my second can of CRC Electronic Cleaner since 2000 when I got my first toyota truck with a MAF sensor that threw a code when dirty. Two phillips screws, unplug the sensor and a few squirts is all it takes. I have 3 different toyotas that all have clean MAF sensors. I typically do it when the oil is draining during each oil change.
     
  5. Richard Davis

    Richard Davis Junior Member

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    Where is sir mass air flow sensor on throttle body?
     
  6. audiodave

    audiodave Active Member

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    Sits above the throttle body in the air filter box.

    Posted via the PriusChat mobile app.
     
  7. edthefox5

    edthefox5 Senior Member

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    Maf should not require so much cleaning it’s past the air filter and on a Prius the air filter is super tight.
    No pollutants are getting to it.
    More talk about the maf on this site than any other car site I have ever been on. Not sure why.
    The maf works by temperature change by air velocity so it would have to be really gummed up to have a negative effect. If it’s not working right it will immed throw a code.
     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    I really needed to clean the MAP (note diff) sensor, it was pretty much oil drenched, located in the intake manifold below throttle body.

    I figured MAF sensor cleaner would be best, and while I was at it cleaned the MAF sensor as well. The latter looked absolutely pristine, like new. Our odometer was around 72K kms.

    Based on my experience, I would suggest to do MAF sensor cleaning maybe every 100K miles, at most, purely precautionary.
     
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  9. JC91006

    JC91006 Senior Member

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    There's no need to clean the MAF sensor unless you're experiencing issues with your car. I only do it when I clean my throttle body, which is about once every 50k miles
     
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  10. edthefox5

    edthefox5 Senior Member

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    Exactly. You will do more damage constantly messing with it than helping.
     
  11. AzWxGuy

    AzWxGuy Weather Guy

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    How hard is it to clean the MAP? I know, I can search for this among the many threads. And I will in a moment. But for now, Mendel, I know you are the keeper of the 2010 service manual document extracts, and I already have the pdf's for removal and replacement of intake manifold and throttle body. I will be looking through those. I am NOT experiencing any mpg issues, but I'm pretty sure that sensor has never been cleaned. It gets me closer to the EGR cooler issue discussed at length in other threads, which still worries me quite a bit. Every time I accelerate and merge onto the interstate I worry about overheating damage to the head gasket caused by an increasingly compromised EGR system. My service writer says don't worry about it, but he is sort of in the business of selling new cars. I wish Toyota would devise an in-car method to clean the EGR path from exhaust manifold to intake manifold, similar to their money-making and mostly useless fuel rail and injector flush.The older and more miles on your car, the more you worry about these things.
     
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Going from memory now, but I believe if you just remove the air intake and air cleaner box, you'll be able to access/remove the MAP sensor. It's to the right of the throttle body, bolted to the intake manifold directly below TB. One bolt, and a connector that might take a little coaxing with a thin blade screw driver to lift it's locking tab.

    If your situation is typical and you pull it, it'll likely be very oil-soaked. The only issue: if you clean and reinstall, it's back into the "sump" that is the low point of the intake manifold. You pretty much have to dive in, remove the throttle body and intake manifold, clean the latter. And to delay reoccurence: install oil catch can.

    Note on the throttle body removal, it can be unbolted, lifted off and put out of the way, without removal of it's coolant lines.

    The MAP sensor looks pretty durable (guess it has to be) and I'm sure something like CRC MAF Sensor Cleaner is ok to spray. If you look that sensor up you'll find it's very pricey btw.

    Pretty sure this was it:

    upload_2018-2-25_10-30-26.png
    (One hole for bolt, the other for locator pin IIRC)
     
    #12 Mendel Leisk, Feb 25, 2018
    Last edited: Feb 25, 2018
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