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Forcing ICE on in P

Discussion in 'Gen 4 Prius Technical Discussion' started by The Professor, Oct 8, 2018.

  1. The Professor

    The Professor Senior Member

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    Just observed something...

    I was in P, and I pressed the accelerator, and the ICE fired up. Released it, and it stopped. Pressed it, it fired up again. Held the pedal down a little bit and the ICE remained on until I released it.

    On the energy flow display, there were no arrows going anywhere.

    I'm wondering why the vehicle does this, and if the display is wrong (i.e. does it charge the battery?). Anyone have any ideas if this might be useful?
     
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  2. qettyz

    qettyz Active Member

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    On Gen3 it actually drains HV battery since MG1 has to be turned to compensate ICE output away. I dont see any reason why Gen4 would be different.

    I have pressed throttle for many minutes to spin ICE(to warm up engine for oil change) and when HV dropped to 2 bars, car started ignoring throttle pedal and started charging HV battery as normally.

    EDIT: also when this is monitored from OBD2(Hybrid Assistant) it shows ~2kW drain from HV if i remember correctly.

    EDIT2: Warm up for oil chage -> car shuts ICE when temp is ~40C, for oil change more is better thats why i warm up engine doing so or drive around for awhile.
     
    #2 qettyz, Oct 8, 2018
    Last edited: Oct 8, 2018
  3. alanclarkeau

    alanclarkeau Senior Member

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    Mine starts and runs till the engine has done it's warm-up, a minute or 2. It shouldn't cut out part way through the warm-up process. Don't put it in "N" though - the battery won't charge, I believe.
     
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  4. The Professor

    The Professor Senior Member

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    Mine ICE was warm (now there's a contradiction!) when I tried this, so that fits.
     
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  5. Prodigyplace

    Prodigyplace Senior Member

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    Another way to force the ICE on is to turn on the front windscreen defogger.
     
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  6. GadgetVirtuoso

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    This would also be useful if you were trying to give someone a jump, as it would produce more power to the battery.
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Here's the third gen Maintenance Mode procedure, not sure if it's still applicable. This will keep the engine running. Do not rev the engine or drive in this mode, it's purely to keep the car idling:

    (e) Activating maintenance mode (Not using the Techstream)
    Perform the following steps from (1) through (4) in 60 seconds.
    (1) Turn the power switch on (IG). (Push the Power Button twice without foot on the brake.)
    (2) Fully depress the accelerator pedal twice with park (P) selected.
    (3) Fully depress the accelerator pedal twice with neutral (N) selected. (You will need to depress the brake to shift to Neutral.)
    (4) Fully depress the accelerator pedal twice with park (P) selected.
    (5) Check that "MAINTENANCE MODE" is displayed on the multiinformation
    display. (Engine should kick in, too. That's a clue... :rolleyes:)

    (Black text from the Repair Manual, my clarifications in red.)


    Again, third gen observation, and not sure how applicable with 4th gen that seems to have greater propensity to shut down, faster/sooner, or not turn on at all: with the car partially warmed and engine running, say stopped at a red light, if I have the cabin temp set to something like 23C, if I just tick it down to around 21C, the engine will shut down. Tick the temp back up, engine comes back on. So maybe having the cabin vent system on and temp set relatively high, is one way to keep the engine running.
     
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  8. Prodigyplace

    Prodigyplace Senior Member

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    NO!
    Toyota says to never jump somebody in a Prius. The engine running does not affect the power to the 12V battery. It is charged by an inverter from the HV battery.

    Jumping a conventional car may not work and would likely fry the inverter. Jumping another Prius may work but if polarity is crossed, expensive damage may occur to one or both vehicles.
     
    #8 Prodigyplace, Oct 8, 2018
    Last edited: Oct 8, 2018
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  9. Prodigyplace

    Prodigyplace Senior Member

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    How is this appropriate in a Gen 4 thread? There is no known maintenance mode in Gen 4.
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Did I not put enough disclaimers for you...

    You could try it, who knows, might still work.
     
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  11. Prodigyplace

    Prodigyplace Senior Member

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    No, not when a much simpler appropriate solution has been given.
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Self appointed moderators get my goat sometimes...
     
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  13. alanclarkeau

    alanclarkeau Senior Member

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    I've "suggested to" the ICE to start - by pressing lightly on the accelerator - in a carpark, driving at 10km/hr and someone walking in front who hadn't heard me.
     
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  14. Starship16

    Starship16 Senior Member

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    Agreed. (y) And unfortunately, there's quite a few of them. In all kinds of discussion forums. I've been "called out" by three or four of those self-appointed Priuschat nuts. Keep up the good work Mendel. (Sorry, that's off topic).

    I like my ICE to run for a few minutes in the morning, I drive slow and get all that oil warm & flowing. Maybe I'm re-living my V-6 Camry days. :LOL:
     
    #14 Starship16, Oct 9, 2018
    Last edited: Oct 9, 2018
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  15. Elektroingenieur

    Elektroingenieur Senior Member

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    It is (and also for the Prius Prime). The only difference for the fourth generation is that the message is now “2WD MAINTENANCE MODE.” The effects listed in the Repair Manual are the same, too:
    • Keeps the engine idling when park (P) is selected
    • Cancels traction control
     
  16. qettyz

    qettyz Active Member

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    So, i found Hybrid Assistant log file where i heated up engine for oil change and did what OP found out: Pressed throttle while in P and this is what happens in Toyota Hybrid:


    MG1 revs quite hard if throttle is pressed to the floor where engine rpm is around 2500
    PSD.JPG
    HV battery drains(SOC):
    CCL and DCL.JPG

    Temps:
    temp.jpg
     
  17. The Professor

    The Professor Senior Member

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    So if MG1 is spinning, and it's only used for starting the ICE and as an electrical generator, and the ICE is running (i.e. it's not being started), then MG1 must be generating electricity, yet the SOC is dropping... What's going on?
     
  18. qettyz

    qettyz Active Member

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    MG1 is spinning to compensate ICE output away since car is at park. If MG1 would be stationary then car would move.
    Car is spinning MG1 and when HV drains out, it starts using it as generator(and ignored throttle pedal like i wroted before).

    EDIT: so car actually uses HV power to spin MG1 if there is no need to charge HV .
    MG1 is also used as part of planetary gearset in PSD, it changes gear rate when it spins in different speed. When driving it can spin even reverse at sometimes to make proper gear-ratio.

     
    #18 qettyz, Oct 9, 2018
    Last edited: Oct 9, 2018
  19. qettyz

    qettyz Active Member

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    Here is log file of PSD when driving, lots of things happening;)
    PSD driven.JPG
    EDIT: please note that these log files are from Gen3 so slight rpm differences may be vs Gen4
     
    #19 qettyz, Oct 9, 2018
    Last edited: Oct 9, 2018
  20. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    MG1 needn't have an electrical load upon it for the engine to warm up. If anything they might be running it as a motor to work as a dynamic flywheel to smooth out the gas engine.

    There's no need for the car to charge- it looks close to half charged, and I understand that is always the target for a "cordless" hybrid like this. You want power in the battery to help you accelerate, and you also want uncharged capacity to offer as braking load. Ideally you have both available at all times.
     
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