2007 getting poor mileage

Discussion in 'Gen 2 Prius Fuel Economy' started by T.S. Elliot, Jun 7, 2018.

  1. T.S. Elliot

    T.S. Elliot Junior Member

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    Hello all. i have a 2007 Prius with 123k miles on it. The battery is original. I changed spark plugs and PCV recently. The transmission fluid was changed at 65k and I will probably be doing it again sometime this summer. Tires are new Michelin Defenders. My mileage is really crap. I first started noticing it in the fall, but I had to live with it all winter because I had to assume that was the cuase. I am now averaging 35-36 mpg. I used to be able to get over 50mpg if I tried and even if I didn't it would rarely be below 45mpg. I took it to Toyota and said I suspect the hybrid battery is bad could you test it for me? They said the battery was fine and that I should get an injector cleaning to improve mpg. Less than thrilled with that response. What do you think is going on? How much does Toyota charge for a new battery? Is it worth going with OEM over a refurbished Dorman? I'd like to try to do it myself. Do you think a new battery would bring the mpgs back up?
     
  2. ITBland

    ITBland Active Member

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    Do you keep an eye on the battery display on the MFD? Do you get wild fluctuations in state-of-charge? (Shows full one minute and almost depleted very quickly, or the reverse, very low one minute and then very full in too short a time?) May be too early to consider the traction battery. It is a car, and there could regular car problems. Any wheels hotter than the others? (wheel bearing/dragging brakes) burning a lot of oil? Been using cheap gas? (injector/MAF cleaning might be the ticket).
    How about the 12v battery? If it is weak, the ICE keeps running (a LOT) to try to charge it.
    Best bet, get something that can show details on the battery (TechStream reads every pair of cells and you can compare, looking for weak cells--which is what the dealer should have done.)
     
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  3. bisco

    bisco cookie crumbler

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    hard to say without cell testing. dormans are a crapshoot. you can get all new cells from a member here for $1,600. if you want to diy. but your battery may be fine, or a grid charger might help.

    i would do an analysis of when the mpg's started declining. new tires? defenders are bad. spark plugs oem?
    have you cleaned the throttle body and maf? run some injector cleaner through a few tanks of gas.
    air filter? oil level?
     
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  4. T.S. Elliot

    T.S. Elliot Junior Member

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    Thanks for your reply.
    I do keep an eye on the battery. I haven't noticed wild fluctuations in the battery, but what I have noticed is that the batter seems to stay almost charged (green, one bar below full) a lot more often that it used to. It also reaches full capacity fairly often. I remember back in the day it seemed to take forever to get a full charge and it was rare. Now with a little bit of a decline it seems I get full up. 12v was replaced brand new in June 2015. I will check on the wheels getting hotter. I replaced pads and rotors on the front brakes myself last fall. How would I check if they are dragging? Just spin it in neutral? I wouldn't know what to compare it to. I mostly frequent Kwik Trip and they use top tier gasoline which consumer reports recommends. The ICE does NOT burn oil and never has. I cleaned MAF and the top of the throttle body as best I could leaving only injectors to be a culprit there... seems unlikely dirty injectors would cause 15 mpg drop? For techstream all I need is the OBD interface and the software? I should probably invest in that if that's all it is.
     
    #4 T.S. Elliot, Jun 7, 2018
    Last edited: Jun 7, 2018
  5. T.S. Elliot

    T.S. Elliot Junior Member

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    Defenders were new last fall, but I had Defenders on previously when I was still getting good mpg. Spark plugs are NGK that I replaced myself recently. I have cleaned the throttle body and MAF. I periodically run regane complete fuel system cleaner through. Probably last done 5k ago. I resist the urges to dump more in. Air filter was just replaced. Oil level is fine and this ICE doesn't burn oil (yet).
     
  6. bisco

    bisco cookie crumbler

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    maybe the prolong charger would be right for you, but a small investment in tech stream to test your battery might be worthwhile.
     
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  7. T.S. Elliot

    T.S. Elliot Junior Member

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    Thanks I just bought a Techstream and it will be here on Sunday. Anything special I need to know how to work it? I should be able to figure it out.

    Interesting comment. I assumed a Dorman refurb was the way to go, but the other user's comments made me pause. My dad has urged me to replace with OEM and forgo the Dorman route. I guess he was right.
     
  8. bisco

    bisco cookie crumbler

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    get your best price on a new oem, and compare it to 2k1toasters price for new aftermarket.

    i'm not familiar with using tech stream, but there are lots of threads here.
     
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  9. ITBland

    ITBland Active Member

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    If the injectors are dirty one (or more) may be stuck open a little and leaking extra gas into the manifold and running really rich, OR they could be clogged or not giving a good spray pattern and running the ICE lean and giving poor performance. There are a few threads in here where people used Techron gas additive for 3 or 4 tanks and got relief from burning oil and better mileage (I would imagine due to cleaning of the injectors.)
    YES! Also listen for noise from the wheel bearings when you do this. (unfortunately, wheel bearings may sound/feel OK when spinning unloaded, and "growl" when spinning with weight on them.) A wheel hotter than the one on the other side of the car could be either brakes or bearings--front to back is not a good check because of the regen on the fronts, check side to side.
    Heck, if wheel alignment is bad, it will ruin tires but also cost in mpg! (hit any bad potholes?)
    Your description of the state of charge changes does sound suspicious. You might want to ask the service dept if they have the battery report from your service, or just show you that the battery cells were showing balanced and OK.
     
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  10. ITBland

    ITBland Active Member

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    What you will usually get is a pirated copy of Techstream that may (probably) set off antivirus alerts. Most people get a "burner" old Win 7 laptop to install it so they don't take a chance with a good laptop with personal information on it.
     
  11. T.S. Elliot

    T.S. Elliot Junior Member

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    Hmm interesting thanks. I actually have a 10 year old laptop that I never use, but it barely works. No battery and very slow. I guess I will try to make it work on that. I have a lot of bank info on my personal laptop.
     
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  12. Wayne

    Wayne Active Member

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    Another possibility -- my hybrid battery took years to die, but lower mileage was one of the first symptoms. You are only 2 years from my end result of changing the HV battery. My Toyota dealer told me the battery was "in spec" to my complaints when it was still in warranty. I think they only really respond to very obvious master warnings. Good luck:

    Bad Hybrid Battery & Mileage Chart | PriusChat
     
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  13. T.S. Elliot

    T.S. Elliot Junior Member

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    I'm leaning towards replacing the battery with OEM. I have two local Toyota dealers. One quoted me $2300 but wouldn't sell unless they did the install. Is this standard practice? My other dealer quoted me $1950 and was willing to sell over the counter. Easy decision I guess. That price seems pretty good, no?
     
  14. Wayne

    Wayne Active Member

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    $1,950 is their retail on the part, that's what they charged me. Anything more is excessive. $2,300 is a good installed price, mine was $2,700 (parts, labor, & taxes included). BTW, my prices are fresh. Just had it done 3 days ago.
     
    #14 Wayne, Jun 8, 2018
    Last edited: Jun 8, 2018
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  15. fotomoto

    fotomoto Senior Member

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    Mine did that too before it failed. Living and driving on flat roads, I thought I was the regen king. Guess not. :rolleyes:

    BTDT it will work fine for this, just use an extension cord. Since I started using techstream so much trying to repair my HV battery, I decided to get a cheap 12v to 120v inverter to run the laptop so I wouldn't have the extension cord PITA.

    Their business, their rules.

    You will also be charged up front a $1350 core charge that's refunded when you return the old battery. You don't get charged that if the dealer does the install.
     
  16. T.S. Elliot

    T.S. Elliot Junior Member

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    Lots of good info here thanks.
     
  17. T.S. Elliot

    T.S. Elliot Junior Member

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    $2700 w/ tax for a full install seems like a pretty good deal. I am going to attempt it myself for better or worse.
     
  18. bisco

    bisco cookie crumbler

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    $1950 is a very good price. best installed price i've seen is $2200. iirc.
     
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  19. ITBland

    ITBland Active Member

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    Take lots of pics! We love a good story!
     
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  20. T.S. Elliot

    T.S. Elliot Junior Member

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    [​IMG]

    How does this look? This was Ready w/ no ICE. All the voltages seem pretty fine from what I can tell. There's gotta be something wrong though... 35mpg in a gen 2 is unacceptable.
     
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