2006 Prius' decline in miles per gallon

Discussion in 'Gen 2 Prius Fuel Economy' started by Joe1987, Jul 29, 2012.

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  1. Joe1987

    Joe1987 Cheyenne Joe

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    Recently, my 2006 has been showing a decline in MPGs. I purchased a K&N filter several months ago hoping that it would help in getting better MPGs. I also watch my tire's air pressure, but the MPGs still fall off. I used to get around 43mpg in town and 45 to 47 on the highway. Now, I'm lucky to get 39mpg no matter where I'm driving.

    I've been thinking of changing the spark plugs since I'm sort of grasping at straws. Also, someone told me that the older the battery pack (NHW20) gets the less MPGs I can expect. Maybe true maybe not! My Prius has a little over 60,000 miles on it and it shouldn't be loosing MPGs.

    Anyone have any thoughts? Should I think about a new battery pack?

    Joe1987
     
    #1 Joe1987, Jul 29, 2012
  2. josh2008

    josh2008 Active Member

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    Been using a/c more frequently lately? A/c puts a pretty significant drain on the hybrid system.
     
    #2 josh2008, Jul 29, 2012
  3. Joe1987

    Joe1987 Cheyenne Joe

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    Yes, I have but the mileage I mentioned was with the AC on, all the time. I live in Florida!
     
    #3 Joe1987, Jul 29, 2012
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    #4 JimboPalmer, Jul 29, 2012
  5. Joe1987

    Joe1987 Cheyenne Joe

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    #5 Joe1987, Jul 29, 2012
  6. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Great, that may rule out some 12 volt battery failure modes that prevent it from getting to 12 volts and cause excessive recharging.

    A second 'common' issue is a dirty throttle body.
    TB cleaning
     
    #6 JimboPalmer, Jul 29, 2012
  7. uart

    uart Senior Member

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    Any other changes recently? Tires in particular.
     
    #7 uart, Jul 30, 2012
  8. Joe1987

    Joe1987 Cheyenne Joe

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    No, same tires that came with the car. I purchased the car in April 2009 with 36,000 miles on it. No changes to the car.
     
    #8 Joe1987, Jul 30, 2012
  9. wjtracy

    wjtracy Senior Member

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    Usually in summer MPG actually improves. On the tires, are you saying normal Prius tires such as OEM GY Integrity or did prior owner make a tire change? Did you go with Optima battery replacement or Toyota? Of course short trips take a toll on average MPG. Make sure your recall work esp. inverter coolant pump replacement has been completed.
     
    #9 wjtracy, Jul 30, 2012
  10. Joe1987

    Joe1987 Cheyenne Joe

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    Thanks for your response.

    Shortly after I purchased the car (April 2009) the coolant pump went out. Thank goodness it was under warranty and the dealer replaced the pump while letting me use a loaner. For whatever reason, it took a month for them to get a pump.

    The tires that came with the car are Bridgestone Signia SE 200, the size is D186/65 B15. I hope this is the information for which you're looking. As for the battery, I purchased it from the same Toyota dealer that sold me the car. I checked it and it's holding a charge.

    Now for the throttle body; is there any kind of spray I can use to clean the TB without having to tear it apart? I'm looking for a quick cleaning solution.

    Joe1987
     
    #10 Joe1987, Jul 30, 2012
  11. wjtracy

    wjtracy Senior Member

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    Usually in summer MPG actually improves. On the tires, are you saying normal Prius tires such as OEM GY Integrities or the
    Re: Tires - I am not familiar with those Bridgestone's as a typical Prius tire , so I hope someone can say if that is valid tire for Prius. Goodyear Integrity was probably what they started out with from Toyota (at least for my 2006 it was).

    Re: Water pump- well Prius has a number of pumps. The main water (coolant) pump often leaks and many have replaced it under extended warranty. Then there is the inverter coolant pump that was a recall item for 2006 models. Yours is presumably fixed already, but if not could be reason for low MPG. So if you have not done so already, you need to check that your vehicle recalls are up to date.
     
    #11 wjtracy, Jul 30, 2012
  12. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    D186/65 B15
    A P at the front means a passenger car, no idea what a D means

    P: Passenger Car
    LT: Light Truck
    ST: Special Trailer
    T: Temporary (restricted usage for "Space-Saver" spare wheels)

    I am guessing the 186 is a typo for 185, I have never seen a tire width not divisible by 5
    65 the tire is 65% as tall as it is wide, very common.
    B would mean it is Bias Ply, a common tire type in the 1970s, replaced by radials almost universally, today

    B: bias belt (where the sidewalls are the same material as the tread, leading to a rigid ride)
    D: diagonal
    R: radial

    15 is the wheel diameter.

    If it is a D185/65 B15 it is a very poor tire.

    Tire code - Wikipedia, the free encyclopedia
     
    #12 JimboPalmer, Jul 30, 2012
    cwerdna and wjtracy like this.
  13. wjtracy

    wjtracy Senior Member

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    Joe by the way, this makes me wonder about the dealer.
    Hard to imagine how it could take a month to replace coolant pump.
    If they were not able to give you a good reason, then it is doubly suspicious.
     
    #13 wjtracy, Jul 30, 2012
  14. Joe1987

    Joe1987 Cheyenne Joe

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    For what's worth, I was told that Toyota was in the process of "re-designing" the pump because they had several pump failures. The pump had to be shipped from Japan. I had a new loaner '09 Prius to drive for the month so I really wasn't inconvenienced.
     
    #14 Joe1987, Jul 31, 2012
  15. Joe1987

    Joe1987 Cheyenne Joe

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    If I remember correctly, it was the pump that keeps the battery cool. Does that sound right?
     
    #15 Joe1987, Jul 31, 2012
  16. uart

    uart Senior Member

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    No, there isn't a pump that keeps the battery cool, there is just a blower (air).

    You're probably thinking of the inverter cooling pump. It's sometimes also called the HV (high voltage) cooling pump which probably led to the confusion (even though the electronics it cools is nowhere near the actual HV battery).
     
    #16 uart, Jul 31, 2012
  17. Joe1987

    Joe1987 Cheyenne Joe

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    Thanks, now I'm just showing my ignorance. Joe1987
     
    #17 Joe1987, Jul 31, 2012
  18. wjtracy

    wjtracy Senior Member

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    Joe your tires have been identified as a possible problem area.
     
    #18 wjtracy, Jul 31, 2012
  19. Joe1987

    Joe1987 Cheyenne Joe

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    How so??? I checked my owner's manual and Google and neither recommended a particular brand or type. Joe1987
     
    #19 Joe1987, Jul 31, 2012
  20. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    185/65R15 is the correct size in the USA for a Gen 2 base Prius
    The correct type is LLR Low Rolling Resistance, so far as I know the only down side to not using LLR tires is reduced MPG.
     
    #20 JimboPalmer, Jul 31, 2012
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