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Noticeably louder engine & dropping mileage

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by kaputnik2003, Feb 20, 2008.

  1. kaputnik2003

    kaputnik2003 New Member

    Joined:
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    2007 Prius
    Over the past couple months, my engine has been noticeably louder when I accelerate up inclines at higher speeds (45+). It used make a sort of nice humming noise but now it sounds like the 200,000 mile Civic that I traded in. And beginning at the same time, I watched my mileage drop from its usual 50.2-50.5 to 46.

    I understand the potential for cold weather mileage drop but the weather here (NYC) has been pretty consistent well before I noticed the drop. My gas station and daily commute is the same. I do regular 5000 mile oil changes & pressure checks and have changed the air filter once. I have a 2007 with 49,000 miles.

    I took it in to Toyota today but they can't find anything obviously wrong and seem to be baffled offering an explanation.

    Do any of you have any thoughts or advice? many thanks in advance.

    Pat
     
    #1 kaputnik2003, Feb 20, 2008
  2. eyesmell

    eyesmell New Member

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    My mileage dropped from about 50 - 47,48 also recently. I'm at the 20K mark.
    (note: we put the wrong oil in, 10w-30 instead of 5w-30. I also suspect this may be the culprit.)

    I noticed my engine sounds a little rough, but I thought maybe it was in my head. I don't really recall what it sounded like when it was new.

    Do you live near an ocean; cause I do, maybe it's the salty air?
     
    #2 eyesmell, Feb 20, 2008
  3. Flying White Dutchman

    Flying White Dutchman Senior Member

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    my dealer put in 10w30 and i don't think it sounds any different
     
    #3 Flying White Dutchman, Feb 20, 2008
  4. donee

    donee New Member

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    III
    Hi Kaput...,

    Well, that is such a small change in mileage it could be anything external. One thing would be traction battery temp. If the battery temp is slowly drifting down, its slowly loosing power. And that means the engine has to slowly get louder to give you the same accelleration.

    Really worried about it, drive down to Florida for a couple weeks and see if the mileage does not pop over the second week.

    Dry air could be the fault too. Dry air is more dense and causes more air drag that damp air.

    Cold ground would be the reason. As the ground slowly drops its surface temp, your tires wont be warming to the same temp, and that would result in more rolling resistance.

    Now if you had said 27, instead of 47 mpg, that would be a cause for concern.
     
    #4 donee, Feb 20, 2008
  5. edthefox5

    edthefox5 Senior Member

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    Two
    What? You lose power if the traction battery is cooler? The engine gets "louder" if the traction battery is cooler???? Thats bad news for people in freezing climes! Where'd you get that from? And yes please drive down to Florida...we can use the tourist dollars! Long way to drive to find where your missing 4 mpg's are. Here they are:

    Check your tire pressure. You can lose 5 lbs of pressure in one cold snap.Goodyear Integritys suck. The difference in 30 lbs to 44 lbs tire pressure is about 4 mpg's in fuel savings. There's only like 3000 posts about that very subject here on Chat. I check my tires about once a week. Bought a nifty $ 19.95 tire inflator recommended here that plugs into the cig lighter & works perfect. My tires are now always 44-40. Good luck and see you soon! Ray in Florida
     
    #5 edthefox5, Feb 20, 2008
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