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35 to 40mpg

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by wackofamily, Apr 17, 2020.

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  1. wackofamily

    wackofamily New Member

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    This is my first hybrid car a 2012 Prius 5. I bought it used in 2017 with only 40k on the odometer. Drove it for 3 years with no issues.
    Currently the car has about 140k on it.
    My issue that I am only getting about 35mpg.
    This started in January all in the same week I replaced the spark plugs, tires and got a oil change.

    Tires 205/65/R15
    Spark Plugs Denso SC20HR11
    New PCV
    Installed oil catch can
    Cleaned EGR pipe, valve and cooler.
    Cleaned intake, intake ports, throttle Body
    Clean the mass air flow sensor.
    Ran sea foam motor treat and engine cleaner multiple times.
    Had transmission fluid change back October 2019.
    No codes Dr Prius or My Foxwell Car scanner.
    Check for for brakes to see if they were dragging no issues

    I pulled the sparks plus yesterday and look good
    20200415_170658.jpeg 20200415_171715.jpeg

    Posted via the PriusChat mobile app.
     
    #1 wackofamily, Apr 17, 2020
  2. tankyuong

    tankyuong Senior Member

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    Tires are too wide affecting mileage
     
    #2 tankyuong, Apr 17, 2020
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  3. Pluggo

    Pluggo Senior Member

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    Keep the tires pumped up to at least 40 psi.
     
    #3 Pluggo, Apr 18, 2020
  4. jerrymildred

    jerrymildred Senior Member

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    Your info says you have a 2012 Prius 4.

    If it's a four, the charts I saw say it takes 195/65R15.
    If it's a 5, it takes 215/45R17.
    Neither one takes a 205.
    From the 2012 Prius brochure:
    Screen Shot 2020-04-18 at 7.15.28 AM.png

    Either way, you didn't mention if they are low rolling resistance and that can make a big difference even with the right size.

    Even with the right sized LRR tires, new tires will hurt gas mileage till they break in. Plus we don't know what mileage you were getting before. Did it go down by 4 mpg or 15 mpg?
     
    #4 jerrymildred, Apr 18, 2020
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  5. bisco

    bisco cookie crumbler

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    what were you getting for mpg's the first 3 years?
     
    #5 bisco, Apr 18, 2020
  6. Grit

    Grit Senior Member

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    According to the subject title of this post, it says it went from 35 mpg to 40 mpg and Said its a 5 model but profile says trim 4. Not sure what else to believe :ROFLMAO:
     
    #6 Grit, Apr 18, 2020
  7. jerrymildred

    jerrymildred Senior Member

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    "Went from?" My version doesn't have those words in the title. It's just a range with no context.
     
    #7 jerrymildred, Apr 18, 2020
  8. bisco

    bisco cookie crumbler

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    no context? how priuschat like :rolleyes:
     
    #8 bisco, Apr 18, 2020
  9. wackofamily

    wackofamily New Member

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    I was averaging 52 mpg before.
    I don't think going up one tire size will decrease your gas mileage by 15mpg.
    Posted via the PriusChat mobile app.
     
    #9 wackofamily, Apr 18, 2020
  10. bisco

    bisco cookie crumbler

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    agreed. i think you have a lot of research to do. there are so many systems on a prius that work synergistically.
     
    #10 bisco, Apr 18, 2020
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  11. bisco

    bisco cookie crumbler

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    use dr. prius and check the hybrid battery health

    get a load test done on the 12v at an auto parts store for free
     
    #11 bisco, Apr 18, 2020
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  12. jerrymildred

    jerrymildred Senior Member

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    Thanks for the added details. Agree that a 2% increase in circumference alone won't cause a 15mpg drop. We still don't know if the new tires are LRR. If they are, then there's definitely something else at play.

    I think I'd be making sure they didn't overfill the transaxle and also double checking all the hose connections related to the OCC installation.
     
    #12 jerrymildred, Apr 18, 2020
  13. Grit

    Grit Senior Member

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    Even if the new tires aren't LRR and heavier? :LOL:
     
    #13 Grit, Apr 18, 2020
  14. ASRDogman

    ASRDogman Senior Member

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    Are you CERTAIN you connected everything when you put stuff back together?
    Very easy to miss something. I would double check. Can't hurt.
     
    #14 ASRDogman, Apr 18, 2020
  15. wackofamily

    wackofamily New Member

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    I was getting any from 49 to 52
    Posted via the PriusChat mobile app.
     
    #15 wackofamily, Apr 19, 2020
  16. wackofamily

    wackofamily New Member

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    They are not LRR ,just Les Schwab house brand Tires. Before those I add set of Michigan non LRR
    Posted via the PriusChat mobile app.
     
    #16 wackofamily, Apr 19, 2020
  17. jerrymildred

    jerrymildred Senior Member

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    Never heard of "Michigan" tires. but I'm not really a student of that industry. Google can't find them either. ;)

    Still, if you were getting around 50 mpg on non-LRR tires, that's impressive. Changing to a different brand still has the potential to make a big difference, especially if they are a house brand that might not be made to the highest standards.

    Sorry, but it looks like no one will be able to give you anything like an accurate diagnosis over the internet -- just places to try looking. Hopefully, you're doing that in between visits here. If you do discover what is causing it, I know we'd all appreciate finding out so that info might help someone else in the future.
     
    #17 jerrymildred, Apr 20, 2020
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  18. wackofamily

    wackofamily New Member

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    Dr Prius results. Good news. Battery and charging system is in good condition. LifeTest_2020-04-23_04-16-08.jpeg FullDiagnostic_2020-04-23_03-46-23.jpeg

    Posted via the PriusChat mobile app.
     
    #18 wackofamily, Apr 23, 2020
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  19. bisco

    bisco cookie crumbler

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    well done, congrats!(y)
     
    #19 bisco, Apr 23, 2020
  20. wackofamily

    wackofamily New Member

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    Still getting 38mpg.
    Posted via the PriusChat mobile app.
     
    #20 wackofamily, Apr 23, 2020
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