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12 v Battery Full 10min Reset

Discussion in 'Gen 3 Prius Fuel Economy' started by Anas Almustafa, Jun 11, 2014.

  1. Anas Almustafa

    Anas Almustafa Member

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    I posted another thread concerning using the 5W-40 oil for the prius and at the same day of the oil change i reset my car by disconnecting the 12 v battery for 10min or more to check and see what happens and if the car Really accommodates the engine coefficients and correction factors to my driving habits.

    My first impression i thought that the car's MPGs went down because of the oil change from 0W-20 to 5W-40 but after keeping the same oil i saw this trend in my gas milage (attached)

    I am starting to think that this car really learns and adjusts for driving habits.

    Just thought i would share this if anyone is interested.

    ****************************************
    Video Update on 12 volt battery reset
    ****************************************

     

    Attached Files:

    #1 Anas Almustafa, Jun 11, 2014
    Last edited: Jun 16, 2015
    Priusguy78213 likes this.
  2. Epiphany2000

    Epiphany2000 Member

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    I have been wondering about this question quite a bit lately. I have a gen II and have disconnected my 12V battery a few times in the last month or so for various reasons (charging the battery, doing some work under the car, etc.), and have not been able to determine if the computer indeed "re-learns" your driving habits. Various internet sources indicate that such is the case, and you might experience some reduced MPG in the process (although it may ultimately lead to improved MPG). Many other posts only mention the loss of various settings, which is to be expected (radio station, disabled reverse beep, etc.).

    One interesting thing I've noticed since disconnecting the 12V battery is that the difference between my calculated MPG and my MFD reported MPG has increased and become more erratic. This doesn't really bother me, but it is an interesting phenomenon. While my MPG seems to have improved, I have been taking longer trips lately & have also reduced my freeway driving speed. Thus, it is difficult to establish a cause and effect relationship between my MPG & disconnecting the 12V battery.

    Does anyone know what the actual consequences of disconnecting the 12V are (other than loss of simple settings such as radio station presets)? Does the computer actually adjust to your driving habits?
     
    #2 Epiphany2000, Jun 11, 2014
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  3. StarCaller

    StarCaller Senior Member

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    your ltft (long term fuel trims) have to be re-learned.
    that should take between 50 & 100 miles, other than that there is not much to 'learn' for the car/
     
    #3 StarCaller, Jun 11, 2014
  4. Epiphany2000

    Epiphany2000 Member

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    Thanks for the clarification. I did some research last night, and "fuel trim" seemed to come up a lot. Your response helped to reinforce what I (thought that I had) learned. Henceforth, I will connect a low current 12V power supply to the electrical system before disconnecting the battery.

    Thanks again :sneaky:
     
    #4 Epiphany2000, Jun 12, 2014
  5. Anas Almustafa

    Anas Almustafa Member

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    Five
    I just made a video on my experience with the 12 volt battery car Full Reset which improved fuel economy.
     
    #5 Anas Almustafa, Jun 14, 2015
  6. bisco

    bisco cookie crumbler

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    i don't know what a car can 'learn' from a driver, but my wife and i often drive each others cars, and it seems to make no noticeable difference in fuel economy.
     
    #6 bisco, Jun 14, 2015
  7. RRxing

    RRxing Senior Member

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    It's just averaging out the two driving styles. The car doesn't say to itself, "Hey, Bisco's driving, let's give him better mpg's..." The car isn't that smart, yet... :eek:
     
    #7 RRxing, Jun 15, 2015
  8. bisco

    bisco cookie crumbler

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    so, would a car with multiple drivers likely get less mileage than a car with one driver? i guess i don't understand the statement, 'your mpg's will improve after the car learns your driving style'. what changes?
     
    #8 bisco, Jun 15, 2015
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  9. Anas Almustafa

    Anas Almustafa Member

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    well i think the car will adjust to the driving style according to usual trips and save the fuel trim bank values to give you what you need.
    say you like sporty snappy driving then it will learn to add more fuel and give you more power.
    if you are driving it in an economic way then it will learn to cut down a little fuel to give you max mpgs.

    I am under going a second test on a second car just did a reset two weeks ago, so i still have about 6k miles to drive and see the results.

    The current car had 90k miles on it from a previous owner and i did a full reset started with 31 MPG, 35 MPG, and now 39 MPG on the same trip, same terrain......etc

    I'll be making a video on it when i am done

    I have done the Full reset on 5 toyota priuses so far.
    Each time you fully reset you have to power up the car and let it run for about 10 minutes or more to allow it to fully configure itself, if you shut it down directly after first startup then you might loose some functionality or settings.

    You are right i have also noticed increase in real gas pump MPG hand calculations and indicated MPG in the car right after full reset, this is because of the fuel trim banks being empty and collecting data to correct and optimize fuel economy.

    its best to fully reset then drive it for about 6k miles (less than 1 oil change) and then you'll see the improvement in MPGs since both trim banks will be set and ready to go.

    I think it will (this is a nice test idea for experimenting with the prius)
     
    #9 Anas Almustafa, Jun 16, 2015
    Last edited by a moderator: Jun 16, 2015
  10. bisco

    bisco cookie crumbler

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    so, since i have accelerated and driven slowly all of the time, when someone who has done the opposite, and i floor our accelerators, he will pick up faster?
     
    #10 bisco, Jun 16, 2015
    Last edited: Jun 16, 2015
    Anas Almustafa and CR94 like this.
  11. Anas Almustafa

    Anas Almustafa Member

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    When flooring the accelerators you'll get the same results regardless of trim levels or driving mode used.

    A good way to put it is that the car will adjust the gas pedal according to your driving habits so its more responsive to your style of driving
     
    #11 Anas Almustafa, Jun 17, 2015
  12. bisco

    bisco cookie crumbler

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    so it kind of does its own eco/normal/power mode thing?
     
    #12 bisco, Jun 17, 2015
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