1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Automatic switch to Power mode in snow....dangerous

Discussion in 'Gen 3 Prius Main Forum' started by mwok86, Dec 16, 2010.

  1. mwok86

    mwok86 New Member

    Joined:
    Feb 21, 2010
    203
    16
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    N/A
    I was driving on an road with about half an inch of snow (just started snowing). When driving down on a slight hill in ECO mode, I came to a stop at a traffic light. When the light turned green, I press the accelerator slowly and it automatically switched to PWR mode and the throttle response was very high.

    This is very dangerous because if you're in rush hour traffic and you're expecting the slow throttle response from ECO mode and it switches to PWR mode suddenly, you might rear end the person in front of you.

    Just want to know if this is by design or a defect.

    Also, when braking at 5-10mph (slow brake)...sometimes it engages the antilock which causes the Prius to slide forward at least 5 feet. I have no idea why it needs to use antilock when it's 5-10mph and I'm braking slowly.
     
  2. jim256

    jim256 Member

    Joined:
    Jun 18, 2009
    317
    69
    0
    Location:
    Eastern NC
    Vehicle:
    2010 Prius
    Model:
    IV
    It does not ever engage Power mode automatically, so something either caused a fault or you may have hit that button in error (gloved hand, maybe?).

    Braking slowly won't engage ABS unless on a slippery surface--the "slide forward" is because the road is slippery, and while ABS is your best bet for a controlled steering stop, ABS may not necessarily generate the shortest stop. It's rapidly releasing and re-applying brakes, basically at the threshold, so you're maintaining steering ability on a slippery or uneven, potholed, surface.
     
  3. 32kcolors

    32kcolors Senior Member

    Joined:
    Jul 14, 2009
    5,683
    952
    124
    Location:
    Redondo Beach, CA
    Vehicle:
    2010 Prius
    Model:
    V
    It's dangerous for you to drive, period.
     
  4. Teakwood

    Teakwood Member

    Joined:
    Jun 23, 2010
    491
    73
    0
    Location:
    New Mexico
    Vehicle:
    2010 Prius
    Model:
    II
    My thoughts, exactly.:D
     
  5. phoenixgreg

    phoenixgreg Senior member

    Joined:
    Apr 7, 2010
    1,157
    288
    66
    Location:
    Phoenix
    Vehicle:
    2010 Prius
    Model:
    II
    I was just playing with this feature a few days ago (in good weather - non rush). PWR mode will re-map the throttle response within seconds. I would think it's only there to impress a friend you let drive it to show Prius can really "get up and go", if need be.

    Well - if you were drag racing with your Prius...maybe you'd use it! :)
     
  6. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,073
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    There is no normal automatic switch to Power mode. If this really happened, then something is wrong. More likely you accidentally hit the power button.

    Tom
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,907
    38,356
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Just having a dyslexic day: I keep reading "Powder Mode in snow".
     
  8. Econ

    Econ Member

    Joined:
    Sep 4, 2009
    329
    26
    14
    Location:
    East of the Berkshires - MA
    Vehicle:
    2010 Prius
    Model:
    Five

    mine three !!
     
  9. kithmo

    kithmo Couch Potato

    Joined:
    Apr 25, 2010
    2,404
    2,773
    47
    Location:
    South Yorkshire, UK
    Vehicle:
    2016 Prius
    Did the PWR light come on ?
    Or was it just that you had given it too much throttle without realising it.
    The pedal is pretty dead in ECO mode until you press it right down, this is one reason I won't drive in ECO in bad weather. I just use normal mode as I'm more used to the feel of the pedal, due to the fact that I use normal nearly all the time.
     
  10. eglmainz

    eglmainz New Member

    Joined:
    Jan 21, 2009
    887
    141
    0
    Location:
    Chicagoland, IL
    Vehicle:
    2010 Prius
    Model:
    V
    I've never seen or heard of an 'Auto PWR Mode' switch in the Prius, but suspect that what may have happened is that you were trying to accelerate on the ice, and your Traction Control kicked in, limiting your acceleration. Then suddenly, you may have hit a 'dry' spot on the road, and kicked forward a bit as a result.

    As for the 'slide' you describe when slowing down, you are either sliding somewhat on snow/ice, and not realizing it, or it's possible that you are experience a slight delay between the regen braking and the disk-braking, which many have experienced what feels as though the car is lurching forward. In reality, this is because of a loss or braking, which can feel like acceleration. Many cars (including my 2010 Prius V) had a change to the software on the braking to reduce this effect.
     
  11. kithmo

    kithmo Couch Potato

    Joined:
    Apr 25, 2010
    2,404
    2,773
    47
    Location:
    South Yorkshire, UK
    Vehicle:
    2016 Prius
    braking lightly at 5-10 mph you are most likely to be regen braking, which is only on the front wheels. The ABS (anti-skid) has no effect on regen braking, so what you felt was one or both of the front wheels losing traction. Pressing the brake pedal harder will activate hydraulic braking and the ABS which will prevent this slide. I've experienced this when travelling across a wet manhole cover and I can reproduce it every time I drive across this manhole cover (on my way home from work) and I allow for it.
     
  12. donee

    donee New Member

    Joined:
    Aug 15, 2005
    2,956
    197
    0
    Location:
    Chicagoland
    Vehicle:
    2010 Prius
    Model:
    III
    Hi mwok..,

    You are not getting ABS action, but dropping into friction braking from Regen. If your friction brakes are wet, or not used allot, they will not match the regen braking pedal force / braking power ratio.

    In standard cars we subcontiously learn to lift brake pedal as we approach a stop, to avoid locking up brakes. In the Prius, you have to learn to do the reverse. Just push harder when you feel the regen brakes kick out. Its no more difficult than the action we use in standard cars, just the reverse of it.
     
  13. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,851
    16,089
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    It shouldn't. Besides, it's takes a few seconds for the mode to take effect (e.g. if you're in ECO mode, driving along and then press the PWR button, the engine doesn't rev up immediately. It takes a few seconds before you'll see an increase in rpm without moving your feet so something isn't right).


    5-10mph.. you're in friction braking (i think regen is down to 8mph??). Maybe when you switched over from regen to friction, the brake pads grabbed the rotors a bit too hard?

    I would say 5ft is a bit exaggerated. I know when I braked hard to stop at a yellow light and I was depressing the pedal steadily until I activated ABS and slid into the intersection, that was about 6 ft from where ABS kicked in and I was going faster than 5-10mph.
     
  14. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,722
    2,121
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    Just been thinking (yeah yeah doesn't happen often eh) about this thread.

    Do you think the op is mixing up Power Mode and the red power band on the hybrid system indicator?
     
  15. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,851
    16,089
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    It's possible. Good thinking.
     
  16. Skoorbmax

    Skoorbmax Senior Member

    Joined:
    Mar 19, 2010
    2,641
    264
    0
    Location:
    Western NY
    Vehicle:
    2010 Prius
    Model:
    II
    The problem with mwok's threads - http://priuschat.com/forums/search/search-id/2783453/ - are that he wastes a lot of people's time with real responses before somebody comes in and points out that all of his threads are reeking of a clinical level of obsession (or trolling, I am not sure which).

    Back to the topic. Mwok's findings are salient and exact in this area. I myself crashed last week three times while driving my Prius and in one circumstance even ran a family off the road. They are ok, thankfully! I have since spent the weekend welding huge bars on the front of the car so that when it does this autonomous jolt of power (138 horsepower when it kicks in is like those rocket boosters some military cargo planes use to help achieve speed during takeoff, no kidding) and slams all the cars ahead the damage to my car can be minimized.

    Actually jokes aside if Mwok is NOT trolling (which is very doubtful) he shouldn't even have a driver's license.

    I really do think he's trolling, though. Too many simply stupid threads for me to think otherwise.

    BTW mwok did you know that after ABS on the prius kicks in 10 times you need to get it serviced at the dealership and it costs about $500?
     
  17. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,722
    2,121
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III

    I think you might be right. The original post indicated that he was a newbie yet the op has way over 100 posts. Hmmm.

    Also, he hasn't posted any follow up to the responses which again is settin my alarm bells ringing. I'm thinking he works for a motor manufacturer or dealer - and not a Toyota one.
     
  18. Skoorbmax

    Skoorbmax Senior Member

    Joined:
    Mar 19, 2010
    2,641
    264
    0
    Location:
    Western NY
    Vehicle:
    2010 Prius
    Model:
    II
    This is his MO. When his posts are called out by enough people he will just ignore the thread and then a week or two later make another one asking or stating some other incredibly crazy question/viewpoint about the Prius.
     
  19. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,722
    2,121
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    And I thought my life was sad! Oh well, there's hope for me yet! ;)
     
  20. Skoorbmax

    Skoorbmax Senior Member

    Joined:
    Mar 19, 2010
    2,641
    264
    0
    Location:
    Western NY
    Vehicle:
    2010 Prius
    Model:
    II
    BTW, I hope the weather is ok, but a plus is that now you can engage in the "How is my Prius in the snow?" threads :)