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Inclinaison sensor spoof to get more electric power

Discussion in 'Prius PHEV Plug-In Modifications' started by Jean Michel, Sep 29, 2014.

  1. Jean Michel

    Jean Michel Junior Member

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    Hello everyone!

    I had this "idea" a couple of days ago and was wondering if you guys think I'm on a good track with that...

    Since I read that it is possible to recalibrate the inclinaison sensors of the Prius in a manner that a faulty gas tank inclinaison sensor can be reseted, I thought about doing it on my car to give my electric motor a greater allowed amperage before Prius computer analyze it is working too strong (emptying too fast the batteries then) and letting the gas engine start.

    In other words, I think it is possible to significantly improve electric power I'm allowed to use on the car before the Prius decides to use gas as well to make the car accelerate and reach its speed.
    I discovered (I long time ago) that going downhill and uphill make a big difference in using electric power and that it is normally "impossible" to climb up a hill (let's say more than a 10 % one) without the use of the gas engine.

    I also discovered this article yesterday night that was at first supposed to solve a gas tank sensor problem but ended up saying it had changed car allowed electric power :
    http://priuschat.com/threads/inclination-sensor-calibration.92867/#axzz3Eild9jZE
    And found this tech sheet with official procedure :
    http://www.greenhybrid.com/images/news/tsb_gasgauge.pdf

    I did the test late at night, placing my car NOT on a levelled ground but instead in a 5 % hill on the road next to my house (nose facing top of the hill). After having acheived the spoofy new inclinaison calibration (with my car now thinking it is on perfect ground level when in fact it is on a small hill), I took the Prius for a ride and discovered this was fully working. I was even able to climb a stronger hill in the neighborhood (around 15 %) WITHOUT using gas!

    Not that I could now fully press down my accelerator pedal but I do now have much more electric power allowed. (I was at a stop sign this morning, with someone behind me anxious to get to work I suppose and was able to accelerate normally. I was not able to do that kind of acceleration before without my gas engine kicking in..)

    Having to deal with a normal Prius that could be a problem (draining the batteries quickly), but since I drive an Hymotion one, I just have plenty of power left for an electric ride!
    So far, I did not noticed a change on fuel level digital gauge but will keep the car full for a while, just in case I don't have a correct lecture of what's left in the tank anymore....

    I also think I will keep this change for another day or two and maybe try a more steeped hill (like the 15 % one I have close to my place) and see what's happening... (procedure can always be corrected in minutes in case I am doing something wrong)

    I also read in the first linked article that it changes amperage of the car regenerating power. But since I can't take advantage of that power, I only manage not to have too many, reaching then full bars of charge (with the common problem of having the gas engine starting because computer thinks original batteries are full). I use then my rear defrost button to lower that extra power. Since it is heat, it needs a unegligeable amount of power and it works!

    Anyway,
    I'll wait for your thoughts on that!

    Regards
    JMB
     
  2. bisco

    bisco cookie crumbler

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    is there any way to make the inclination sensor display on the mfd? i would love to know if i'm going up or downhill.
     
  3. Easy Rider 2

    Easy Rider 2 Senior Member

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    NO. Flawed logic.

    What makes the engine operate differently depending on the incline is NOT a measurement of the incline but a tiny measurement of ground speed versus energy input. That way it takes in all of the factors, like wind speed for instance, without actually measuring the wind speed either.

    On any given incline, you can make the gas/electric ratio about anything you want just by varying the position of the throttle.......almost.
     
  4. Easy Rider 2

    Easy Rider 2 Senior Member

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    You could use the old pilot's trick. Tie a weight to a piece of string and hang it from the rearview mirror. :)
     
    krmcg, Jean Michel and bisco like this.
  5. Jean Michel

    Jean Michel Junior Member

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    Ha. ha. Very funny. :cool:

    I drive the exact same road everyday. Just with the small hill at the end of my home entrance, I can see a noticeable difference!!

    I'm not a blind believer in this, but I am questioning myself a lot...

    As I said, I will wait a couple of days and see if I can get a significant MPG difference...

    Easy rider 2, I do like your "speed versus energy" input! What I don't understand is the amp change (seen with the scan gauge) in the threat :

    Inclination sensor calibration | PriusChat

    To me, it's still a mystery!!
     
  6. Jean Michel

    Jean Michel Junior Member

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    Ok, it's been nearly 3 weeks now and here's my position on that sensor tricking idea :

    It does make a very-tiny-little-slight difference about electric power I can get but that is only at very low speed (less than 15 MPH).

    Plus, I did not see any "power" change between a 1-2 degres spoof and a 15 degres one. I have tried very steeped hills and almost levelled ones and it does the same effect... So I decided to reset the sensor again to a minor 1-2 degre fake correction.

    After a 300 miles evaluation, lets say I have done a 90,47 mpg instead of the 87,1 mpg I could get before...
    (Again, I have drive the exact same road with same atmospheric/traffic conditions)

    So,
    With the problem of having an unaccurate idea of what's left exactly in the gas tank, I feel this idea may not be as good as I thought at the beginning.... It's a too small difference for the disadventage it generates.

    To me, this is the End of that project.

    :)

    Good weekend to you folks!!

    JM
     
  7. bisco

    bisco cookie crumbler

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    good experiment, reasonably controlled, sensible conclusion, well done!(y)