My Gas Motor turns on as soon as touch the accelerator

Discussion in 'Gen 2 Prius Fuel Economy' started by grccmetech, Feb 12, 2018.

  1. grccmetech

    grccmetech New Member

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    As soon as I push the gas, even if I lightly tap it, the gas engine turns on. its effecting my gas mileage I am currently getting 22-32 depending on how much highway driving I do. I have replaced both o2 sensors because it was throwing a code and acting up terribly, but now its good except the electric motor doesn't engage without the gas motor engaging aswell. I also changed the fuel injectors spark plugs and the oil. finally swapped 12v battery but even the new battery still is at 11.6V after overnight the old one was at 11V so I don't know if that has anything to do with the inverter or not. please help
     
  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    How many miles on this vehicle?

    How did you read the thrown codes previously?
     
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  3. grccmetech

    grccmetech New Member

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    273k I read it with a snap on scanner
     
  4. Drafty01

    Drafty01 Junior Member

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    What voltage does your 12V battery charge at? Should be about 14.0 to 14.5V.
    11.6V is basically flat, and will likely ruin it in a short time.
     
  5. fotomoto

    fotomoto Senior Member

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    This.

    Sounds like the HV side of the equation is not working properly or possibly at all. Usual suspects: inverter, inverter pump and/or HV battery weak/failed.
     
  6. Dxta

    Dxta Senior Member

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    Your HV battery pack might be heading South already. No matter what you do, until the HV part of the equation is sorted out, before you'd get a relief.
     
  7. grccmetech

    grccmetech New Member

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    ya i definitely suspect the hv battery. my aux battery does charge at 14.1V. The inverter pump is working, and the inverter itself has to be working because the car drives fine for the past 3 months. I happen to have access to a snap on scanner so I can read the voltages of the individual cells in the hv battery. i am planning on testing them after letting it sit 24hrs to see if i can get away with replacing just a couple modules. my question is, is there any other way to test the hv battery?
     
  8. bisco

    bisco cookie crumbler

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    i think torque pro is a decent prius scanner.

    but i have concerns about the second 12v battery you installed. is it new? did you check the voltage before installation?
     
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    The Prius is typically pretty darn good at coding an HV battery when it's getting to be time to replace it. If there's no HV battery codes, I don't know that I would focus a lot of energy or money in that direction. If your brand new 12v battery is 11.6v, I think I'd rectify that situation first. Put a low amp charger on it and top it off. My manual says it should be limited to 3.5 amps.

    Start with the obvious things first. Tearing into the HV battery with no codes seems like unwarranted business to me.
    Get a good 12v charge, re-install the battery, and test it out. Just keep in mind you've put new O2 sensors in, and cleared all the ecu maps when the 12 v was off. And I'm sure the weather is cold as a witches t*t where you are. None of those things are immediate positive things in your corner. What injectors/plugs and oil did you install? Is Techstream available to you?
     
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  10. uart

    uart Senior Member

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    The main things I've noticed that can cause the engine to be a bit "hair triggered" in wanting to start like that are:

    1. A weak HV battery.
    2. Low state of charge (4 or less bars on the energy monitor screen).
    3. Very high temperatures (including blocked rear cooling fan).
    4. Very low temperatures.

    Before worrying too much about number 1 on the list, check if any of the others are applicable. Have you checked the rear cooling fan for blockages (dust,fur,lint etc).
     
  11. Astrong1984

    Astrong1984 New Member

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    This may sound rudimentary, but do you have the heat on, and is it cold outside? I am in Colorado and when it is cold out, both of my Gen2s act that way.
     
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  12. grccmetech

    grccmetech New Member

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    i am going to test the HV cells today after letting them sit over night. and ill test the12v battery before returning it.
     
  13. Lucifer

    Lucifer Senior Member

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    It' an 06, the traction battery is 12 years old, just buy a new from Toyota traction battery and get five years of 50+ mpg, and make sure that the plugs you put in are good, your mileage is really low, missing cylinder low.
    Last word was Toyota is selling the traction for 2000$, not a bad deal, did you buy a new 12v or swap a used one?
    Is your air pressure 40, is your emergency brake cable binding?
     
  14. grccmetech

    grccmetech New Member

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    i let the car sit overnight and all the voltages are within .2v. i tested the 12v out of the car and it passed the test. im starting to think that the average mpg is off. i recorded my miles when i filled up so i will do the math at the end of the week. my battery fan works too btw i did a test on the snap on scanner
     

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  15. grccmetech

    grccmetech New Member

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    i will add that at 40% SOC the volts were at 15 i dont know if that has anything to do with anything
     
  16. SFO

    SFO Senior Member

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    That scanner looks pretty advanced, like to the point of being able to scan/log/play back live data.

    Can you scan while putting a load on the HV battery?
     
  17. grccmetech

    grccmetech New Member

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    ya i push the gas or put it in reverse not much seems to happen with the voltages
     
  18. golfmk681

    golfmk681 Member

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    How are you guy's MPG when its super cold? Should we see low 30s when the car typically gets 40s mpg in regular weather?
     
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  19. audiodave

    audiodave Active Member

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    Trickle charger the 12volt couple times a week. Car charger sucks.


    Posted via the PriusChat mobile app.
     
  20. audiodave

    audiodave Active Member

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    Did you notice improvements in power after the injectors where replaced?

    Posted via the PriusChat mobile app.
     
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