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Drop off in mileage

Discussion in 'Gen 3 Prius Fuel Economy' started by BigAl61, Aug 6, 2017.

  1. BigAl61

    BigAl61 Junior Member

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    Hello to all of you. I a 2012 Prius 3 owner, I have been getting between 52-55mpg. I recently took a 600 mile round trip and now my mileage has not gone over 46mpg. I am faithful with the routine maintenance, from Alignment, balance and rotation, oil changes and Cabin and air filter changes. This is frustrating. Anyone have any ideas as to why? Please advise! Thanks to all who take the time to provide me with any help.
     
    #1 BigAl61, Aug 6, 2017
  2. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Hey! Have you bought new tires lately, or been blasting the A.C full tilt? Or maybe both? How many miles on your car?
     
    #2 Aaron Vitolins, Aug 6, 2017
  3. Sam Spade

    Sam Spade Senior Member

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    And what SPEED were you going on that trip ?
    Faster average speed than your normal routine ??
    Extra passengers or other cargo ???

    That REALLY isn't that much of a difference.
    See what happens next.
     
    #3 Sam Spade, Aug 6, 2017
  4. bisco

    bisco cookie crumbler

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    how are you measuring mpg?
     
    #4 bisco, Aug 6, 2017
  5. BigAl61

    BigAl61 Junior Member

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    I had 2 other passengers and alot of extra weight on the trip. I knew that my mileage would be less. My problem is that ever since the trip my mileage has not gone back to what I was getting before the short excursion.
     
    #5 BigAl61, Aug 7, 2017
  6. BigAl61

    BigAl61 Junior Member

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    I use a app to record my mileage. I keep track of every mile that I drive. I only fill up, I don't just add $5 here and there. The app keeps the mileage.
     
    #6 BigAl61, Aug 7, 2017
  7. DavidA

    DavidA Prius owner since July 2009

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    My mileage on my 2010 with 49,000 miles on it (bought July 2009) dipped very sharply the last 2 years I owned it. The most I could get from a tank was 42 in the summer and that was with a new 12v battery installed. I solved that with a Prius Prime Advanced a month ago. It only took 2 weeks to pin the MPG meter at 199.9, and it hasn't moved from that yet. Very happy so far.
     
    #7 DavidA, Aug 7, 2017
  8. jdonalds

    jdonalds Active Member

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    The mileage in our 2008 Prius dropped from the usual mid 40's to mid 30's one day. It lasted through three tanks of gas until I fixed it. I thought it was the traction battery so checked for codes and looked at the battery voltages etc with an ODBII setup. Nothing. Finally I figured out it wasn't the EV mode but rather the PIP that was causing the mpg drop.

    Having had good luck with SeaFoam I thought I'd give it a try. I dumped about 1/2 can of SeaFoam in and the car returned to the mid 40's mpg and stayed there for the next couple of years until we sold the car with 173K miles on it. I figure it was just some dirt in the injectors best guess.
     
    #8 jdonalds, Aug 7, 2017
  9. Sam Spade

    Sam Spade Senior Member

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    Do you know how averages work ?
    IF.....your app is keeping a running average, like the onboard display will do if you don't reset it, then the poor trip performance will have a negative impact on your long term average for a LONG time. Once you burn extra gas, you can't get it back no matter how hard you try.
     
    #9 Sam Spade, Aug 7, 2017
  10. bisco

    bisco cookie crumbler

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    how many tanks have been low, since you got back from the trip?
     
    #10 bisco, Aug 7, 2017
  11. NeilPeart

    NeilPeart Hybrid & PiP Convert

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    LE
    When the mileage drops sharply should we be looking at the following:

    Step 1:
    Clean Traction Battery Fan

    Step 2:
    Clean EGR full system (cooler, valve, pipe, runner ports in intake plenum, etc.)
    Replace PCV Valve & clean PCV hose
    Clean Intake Manifold & PCV hole
    Clean throttle body

    Step 3:
    Replace spark plugs & clean injectors
    Clean MAS/MAP sensors

    Anything else I missed (other than the new Oil Catch Can idea that's gathering momentum; sounds like a good idea but seems a bit maintenance-heavy)?
     
    #11 NeilPeart, Aug 7, 2017
    Last edited: Aug 7, 2017
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