MPG increase due to new plugs and 12v battery

Discussion in 'Gen 2 Prius Fuel Economy' started by E. J., May 28, 2015.

  1. E. J.

    E. J. Junior Member

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    FYI, I recently changed the spark plugs and 12v battery in my '08 Prius at 120,000 miles. Parts from the Toyota dealer.

    I have an increase of about 2 to 3 mpg from before (taking into account the summertime temperatures). No other changes, and car was running fine prior.

    Nice surprise!

    E. J.
     
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  2. bisco

    bisco cookie crumbler

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    excellent!(y) what battery did you go with?
     
  3. JC91006

    JC91006 Senior Member

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    A Toyota dealer battery
     
  4. bisco

    bisco cookie crumbler

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    oh yeah, good call.:rolleyes:
     
  5. E. J.

    E. J. Junior Member

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    Toyota TrueStart battery and Toyota plugs. $199.95 for battery and $52.28 for the plugs in Mt. Laurel NJ. I probably paid too much, but I've always been happy with the parts at that dealer.

    E. J.
     
  6. srellim234

    srellim234 Senior Member

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    I'm looking at the 120,000 service in a few weeks and plan to replace the 12v battery as well. Having just bought the car, we're willing to spend extra on this major service to make sure the car is as "new" and set up for the long run as it should be. Reading all the maintenance tips I'm getting a little confused.
    What else should I be looking at having them replace (drain, flush, etc.) that is not on the service passport but probably should be done?
     
  7. JC91006

    JC91006 Senior Member

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    There should be a date code on the 12v battery and you can test the battery to see how good it is. There's no need to replace a battery if it's still good. If the battery is past 5 years old, then you should replace it.
     
  8. srellim234

    srellim234 Senior Member

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    The CarFax shows the battery has been checked but never replaced. The dealer I'm taking it to is the same one that has serviced it since 2008 for the previous owner. They confirmed it's still the original and 9 years old.
     
  9. geekwithoutacause

    geekwithoutacause Junior Member

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    9 years old ???? Doubt it but if it is, you are on borrowed time.
     
  10. srellim234

    srellim234 Senior Member

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    Went ahead and got everything done yesterday at Crown Toyota. New 12v battery, spark plugs, a lot of different fluids drained and replaced, 120,000 mile maintenance passport inspections done. If it improves the mpg a notch like you got, E.J., so much the better. If it doesn't I still have a lot more peace of mind when the family's out on the open highway.

    A humorous side note: obviously the work they did was going to reset things like the mpg on the display and remove the radio presets.. I wasn't even thinking of that when I pulled away from the dealer and saw 17 mpg on the screen. The thought quickly flashed through my mind, "How did they drive the car to thrash the mileage so badly?" After about 5 seconds I realized it was 17 mpg calculated over less than a mile, had a good laugh at myself and drove on home.
     
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  11. srellim234

    srellim234 Senior Member

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    I do think Thursday's service with the 12v battery, spark plugs and fluid replacement as well as the tire replacement a week ago helped. Went over the Cajon Pass to California City, then Ridgecrest and back home in mid-90s heat yesterday. The four of us in the car weigh a combined 600+ lbs and still got 52mpg over the 315 mile trip. Yes, I'm improving at adapting to the Prius driving style but I don't believe that accounted for all the improved gas mileage over the same trip two weeks ago (38.7mpg).
    Gas just went up 30 cents a gallon overnight. They're talking about it jumping again. If we still had to do it in the Rendezvous we couldn't afford the gas to make the trip. Thank you Prius!
     
  12. HOWARD B PRICE

    HOWARD B PRICE Junior Member

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    I had my 12 volt replaced a month ago. Live in Vegas and it was 8 years old. Didn't want to chance it. Have 95m miles. Should I replace plugs and how easy is it to do myself?
     
  13. bisco

    bisco cookie crumbler

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    not until 120k. start to think about fluids, check the owners manual. have you done the serpentine belt?
    some folks like to change the tranny fluid, even though it's not in the manual.
     
  14. geekwithoutacause

    geekwithoutacause Junior Member

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    plugs are not needed yet. I would do the transmission fluid for sure. Very easy to do. Look at some of the howto's online. Verify you empty the transmission and not the inverter coolant. The plugs are close together. Tranmission drain and fill plugs are in one line, top to bottom.
     
  15. Wolfy90503

    Wolfy90503 Junior Member

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    I am getting 50+ mpg now after changing the oil, yokohama tires, and spark plugs. The previous owner got only 39mpg even with a new hybrid battery.

    IMG_20150730_074505179.jpg
     
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  16. bisco

    bisco cookie crumbler

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    well done!(y)
     
  17. Lord Byron

    Lord Byron Member

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    Hmmm... where did you drive those 27 miles to get 57.2 ave? I bet you probably weren’t going above 25 with no stop signs.. lol
     
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