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Gas mileage

Discussion in 'Gen 2 Prius Main Forum' started by chrisasst, Aug 21, 2014.

  1. chrisasst

    chrisasst Junior Member

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    Ok fellow priusers. Bought 2009 Prius almost 2 years ago. When I first got it, I could drive about 80 miles only using one bar on the fuel gauge from full. The screen said I was getting 46-47 mpg.
    Now I am using several bars and it is down to around 42 mpg. I have new tires on it. The pressures are correct.
    What else can I do to get the mileage back up?
    It has around 105k miles on it.


    iPhone ?
     
    #1 chrisasst, Aug 21, 2014
  2. tanglefoot

    tanglefoot Whee!

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    Which new tires did you put on? Tires vary considerably in their rolling resistance. Some tires also roll better once they have been worn a bit.

    You might try some higher tire pressure to see how it does. I like 42 psi front, 40 psi back.

    There are numerous factors that affect fuel economy. The difference could be due to any combination of them, but since you just changed the tires, I'd suspect that first.

    This post will probably be moved to the Fuel Economy section.
     
    #2 tanglefoot, Aug 21, 2014
  3. JC91006

    JC91006 Senior Member

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    You can check and change the following:

    1. Engine air filter
    2. Spark plugs
    3. Clean Throttle body and MAF sensor
    4. LRR tires
    5. Different gas station
    6. Remove some of the lead on your foot.
     
    #3 JC91006, Aug 21, 2014
    Last edited: Aug 21, 2014
  4. chrisasst

    chrisasst Junior Member

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    It was dropping mpg even before the new tires. I usually keep air pressure Around 35.
    Are spark plugs easy to change my self?
    Air filter is new.


    iPhone ?
     
    #4 chrisasst, Aug 21, 2014
  5. JC91006

    JC91006 Senior Member

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    Yes spark plugs are very easy to replace yourself. But I don't think that is the cause of the loss mpg. The plugs are recommended to be changed at 120k miles. It may or may not help.

    Since you've recently got a new air filter and tires, I would just reset the computer and recalculate your mpg. Get a good average after 3 fill ups.

    Air conditioning use also affects mpg. So if the temperature has been really warm and you are using your ac more than usual, it should explain the loss mpg.
     
    #5 JC91006, Aug 21, 2014
  6. fuzzy1

    fuzzy1 Senior Member

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    #6 fuzzy1, Aug 21, 2014
  7. wjtracy

    wjtracy Senior Member

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    I just replaced my plugs at 135k miles. There is a video on YouTube that helps.
    I am not expecting that is the problem. The plugs are iridium tipped so the sparking zone is amazingly well preserved.
     
    #7 wjtracy, Aug 21, 2014
  8. dorunron

    dorunron Senior Member

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    +1 on the "Fuel Economy Complaints/Queries. I strongly suggest to the OP that they copy and paste the questionnaire into this string and answer ALL of the questions. Then we will have something to work with, otherwise it is a "guessing game".

    Ron (dorunron)
     
    #8 dorunron, Aug 21, 2014
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