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Mileage drop for no apparent reason

Discussion in 'Prius v Main Forum' started by HaveNoCents, Jul 5, 2012.

  1. HaveNoCents

    HaveNoCents Conservative Tree Hugger

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    Five
    We recently got back from a 2800 mile trip. Our v now has 10,600 miles on it. We have been averaging 41mpg until the last two tankfuls. For some strange reason we got 34.5 displayed on our last tank, 32 actual, and right now after 90 miles we are showing 30.5 displayed. My wife drives the car 98% of the time, but even when I use hypermiling techniques the car is not yielding the past displayed results. We are about to take it in for the 10,000 oil change. We live in Texas so it is over 90 everyday, but we keep the temperature on 76. Our driving habits have not changed at all.

    Any Suggestions?
     
    #1 HaveNoCents, Jul 5, 2012
  2. Rokeby

    Rokeby Member

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    Did you encounter very dusty conditions on your recent trip?
    If so, your Mass Air Flow (MAF) sensor and throttle body may
    be in need of cleaning.

    Another possibility is a bug got past the air filter and is fouling
    the MAF.

    It is an easy matter to open the intake air filter and check.
     
    #2 Rokeby, Jul 5, 2012
  3. rjparker

    rjparker Tu Humilde Sirviente

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    Make sure your tire air pressures are at least 35 front and 33 rear. Buy name brand gas such as Shell or Exxon. Really cheap gas (or some gas bought at high altitudes) may have low octane which could cost mpgs at sea level.
     
    #3 rjparker, Jul 5, 2012
  4. bisco

    bisco cookie crumbler

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    have them check your 12v to make sure it's upto snuff. also, even tho the temp is set to 76, if it's hotter outside than it has been, you're gonna get worse mpg's.
     
    #4 bisco, Jul 5, 2012
  5. HaveNoCents

    HaveNoCents Conservative Tree Hugger

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    Five
    Thanks for the responses, I will check into all suggestions. Tire pressure is sitting at 42/40 so I know we are good on that.

    I know a bad 12v can give you crazy readings, but how could that have a bad effect on actual mileage? The car did sit for two weeks, but we drove it 1800 miles after that two weeks with no decrease in mileage on the highway.
     
    #5 HaveNoCents, Jul 5, 2012
  6. HaveNoCents

    HaveNoCents Conservative Tree Hugger

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    Five
    Well here is an update. As it turns out the mileage drop had a very good reason. It seems my wife no longer shuts the car off when she is on the ferry. Basically it's like being stuck in traffic without moving an inch for approximately 50 minutes.
     
    #6 HaveNoCents, Jul 16, 2012
  7. JimN

    JimN Let the games begin!

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    If the 12v isn't holding a charge then the car will keep trying to charge it. Guess where that electricity comes from.

    Yup. Sitting for 5 minutes usually won't make a difference. 50 minutes will drop anyone's numbers.
     
    #7 JimN, Jul 16, 2012
  8. schinia

    schinia Member

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    it didn't drop my numbers, with the weather in the 90s, i sit in the parking lot w/the car running for an 1 1/2 hours, while my wife has her back treatments. still get 45 mpg (calculated)
     
    #8 schinia, Jul 17, 2012
  9. OWG

    OWG Junior Member

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    Sat at the drive-in for about 4 hours running (no AC) and did not have a noticeable affect on my mileage.
     
    #9 OWG, Jul 19, 2012
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