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happy but need help with MPG

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rmacguy1949, Jun 10, 2013.

  1. rmacguy1949

    rmacguy1949 Junior Member

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    Need advise please:

    original owner 2008 Pack 2 Prius. Not driven for 11 months between 2008 and 2012.

    at 135,000 miles MPG was 52.7. Pretty constant over total mileage.

    Haven't changed driving pattern or habits.
    Did change 2 things at 135,000 miles.

    1. Got a 4 wheel alignment (thought it was time)
    2. Put new set of Goodyear Integrity Tires on.
    (I know lots of bad press but I have used 3 sets of these and 1 set of Michelin,
    with better results from Goodyear.) Bad pressure 40, front pressure 38.
    I always loose about 1.5 mpg for the first 10K but then back to normal.

    Car now has 145,000 and MPG's down to 48.5.

    I have had the Inverter coolant changed.

    I have checked my 12Volt battery 2 ways(with meter and MFD display) and it appears o.k.

    12.63 volt at jump point after 24hrs idle. 12.23Volt at jump point after 24hrs idle and car
    with air on.

    I have questioned my service rep about throthel body cleaning and he informs me
    that they do injector cleaning. In the past I have had bad luck with injector chemicals
    with O2 sensors. Is there anything else I should try before this?

    Thanks very much in advance

    Richard
     
    #1 rmacguy1949, Jun 10, 2013
  2. Britprius

    Britprius Senior Member

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    Richard, a good point to start would be MAF, and throttle body cleaning.

    Injector cleaning will not clean these items, and with E10 fuel the injectors should be clean anyway.

    The 12 volt battery reading seem reasonable.

    Do you have the readout from the alignment? if so could you post it, and have you changed the plugs if so at what mileage?

    John (Britprius)
     
    #2 Britprius, Jun 10, 2013
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    New spark plugs?

    Check valve clearance? (I understand this is pretty involved, with shim system used)
     
    #3 Mendel Leisk, Jun 10, 2013
  4. Munpot42

    Munpot42 Senior Member

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    You might spend a lot of money chasing 3.5 MPG, is it worth it to you?
     
    #4 Munpot42, Jun 10, 2013
  5. Britprius

    Britprius Senior Member

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    I make it 4.2 mpg, but the real point is the decline could continue if the reason is not found. Plus the risk of possible damage to the engine or HV battery if it is made to work harder.

    The problem could be something as simple as spark plugs or at the other end of the scale (not wishing to alarm the OP) problems with the HV battery. Leaving things to get worse is not the best option.

    John (Britprius)
     
    #5 Britprius, Jun 10, 2013
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I agree that if the iridium spark plugs were not replaced at 120K miles, that needs to be done now.
     
    #6 Patrick Wong, Jun 10, 2013
  7. rmacguy1949

    rmacguy1949 Junior Member

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    changed plugs at 95,000. Had throttle body cleaned last week. no help milage now slipping to 48.4

    Can I read the I know how to read the SOC with the scan guage, but can I read the HV battery cell individually with a scan guage II?

    thanks for any replys or help
     
    #7 rmacguy1949, Jul 9, 2013
  8. wjtracy

    wjtracy Senior Member

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    48.4 is very good MPG for Gen2. Don't forget new tires alone cause a decrease in MPG. TireRack.com has a nice article about that (below). Although sounds like you are should be getting over this impact. Basically 48.4 could be no problem (our average is about 47) at 122k miles. I do not know if you are quoting MPG from MFD readout or calc'ed from fill-ups.

    Check out the user survey we have here to evaluate MPG issues, many questions that you should answer and post here for comment. If I had to say something, think about changing the 12v to an Yellow top Optima on the assumption you have orig 12v in there.

     
    #8 wjtracy, Jul 9, 2013
  9. vskid3

    vskid3 Active Member

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    Are the tires at the same pressure as the old ones? While it won't help you find the cause, you could bump up the pressure in them to help regain some mileage in the meantime. I run sidewall max in my Escape and Prius, I don't mind the firmer ride.
    When you had the alignment done, did they give you a sheet that showed the before and after values? Maybe the previous alignment was off by Toyota's standards but allowed it to roll easier.
     
    #9 vskid3, Jul 9, 2013
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