Mysteriously Entering Hybrid Stage4 ?

Discussion in 'Gen 2 Prius Technical Discussion' started by uart, Oct 25, 2010.

  1. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,166
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    For those who know about the Gen 2's five stages of hybrid operation, we know that if you get the car up to operating temperature and then stop with the ICE running, then it will cut out after about 5 seconds and then enter "golf cart mode" hybrid stage 4.

    Ok the above always works, it definitely gets you into stage4, but it doesn't seem to be the only way to do it. Sometimes when I'm driving and I definitely haven't even stopped I suddenly find that I'm in hybrid stage 4 anyway. It usually happened that I release the accelerator pedal at some speed below 34 MPH and expect to see the ICE still running but it stops. After that I find it's in full "golfcart mode" stage 4, ICE cut's out at any speed when I release the gas pedal.

    Ok I'm not complaining. This is a good thing, I love being in stage 4, I wish it would be in stage 4 all the time. I just find it so mysterious, even after learning about the "idle for 5 seconds thing" which greatly helped me understand part of the mystery, it still surprises me sometimes by entering the stage 4 in some as yet unknown way. Has anyone else noticed this?
     
  2. Bob64

    Bob64 Sapphire of the Blue Sky

    Joined:
    Apr 9, 2007
    1,540
    84
    0
    Location:
    Virginia
    Vehicle:
    2007 Prius
    Model:
    N/A
    Perhaps your in stage 2? Whats your water temp at?

    from hobbit's website:
    S2:
    When the system temperature reaches 40 degrees C. (104 F.) the
    computer goes to Stage 2 operation. The original Japanese poster gave
    more detail than I clearly remember, but it appears that in Stage 2
    the ICE will shut off if it is not needed to provide power.
     
  3. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,166
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    I haven't measured the water temperature but I'm absolutely certain that it's not in stage 2. I'm in a fairly warm climate and this situation always happens after I've been driving for longer than it takes me to reach stage 3. Also, after it happens and I keep driving then I usually test it a few more times (after more driving) to be sure it's really in stage 4. If it was stage 2 then it wouldn't persist like this. In the climate here I'm usually into stage 3 by about three minutes tops.

    I'm practically certain that the car is at full operating temperature when it happens and I'm 100% certain that I haven't stopped. So it hasn't entered stage 4 in the normal way but somehow it's in stage 4 just the same.

    BTW. This doesn't happen all the time. It's just an occasional thing and I have no idea why. I wish I knew what it was that had caused so I could do it all the time. :)
     
  4. Rokeby

    Rokeby Member

    Joined:
    Jan 21, 2008
    3,033
    703
    75
    Location:
    Ballamer, Merlin
    Vehicle:
    2008 Prius
    it would appear that you are in Stage 2 or 3.

    See the attachment to the OP in this thread.

    I need to ask about the "idle for 5 seconds thing." I understood that
    after you get to Stage 4 and are stopped with the ICE off, you should
    wait some 5 or 6 seconds, and then do an "idle check," which is just a
    slight, quick stab at the go-pedal to get the ICE to come on
    momentarily.

    IIRC, Stage 4 is "switched." That is to say, once all the preconditions are
    met, the HSD stays in Stage 4, even though one or more of the
    preconditions falls below the threshold value, such as block/coolant
    temp falling below 157 degF. (Again, I've thought that the "idle check"
    was one of the Stage 4 preconditions and required for the "switch" to
    be activated.)

    I could be way wrong on this! Comments/corrections are welcomed.
     
  5. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,166
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    - No it's definitely not in stage 2. I've already explained that.

    - No it's definitely not in stage 3 because the behavior in stage 3 is quite different (ICE wont cut out if you begin your glide below 34 MPH in stage 3).

    Ok so no one believes me so I guess no one else has ever had this happen?

    For more info on the stages please refer to this : http://www.techno-fandom.org/~hobbit/cars/five-stages.txt
     
  6. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,166
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    Yeah if you stop from more than 35 MPH in stage 3 then the ICE will be off, so it wont progress into stage 4. Stabbing at the go pedal will get it to idle and after 5 to 6 seconds enter stage 4.

    All I'm saying is that sometimes (not very often mind you) I seem to end up in stage 4 without having stopped and gone through the idle thing but I can't find any rhyme or reason to it.

    That definitely could be true. Someone (I think it was Mike Dimmick) said that the 5-6 second thing was something to do with a MAF calibration procedure. Basically it can only do this calibration if it's up to operating temperature and stopped with the ICE at idle. So that's why it keeps us stuck in mode 3 with the engine running when we'd rather it wasn't, because it just wants to get the calibration done.
     
  7. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,961
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Yes, I have noticed it too once in awhile. It is because you can enter S4 if you stay under 7 mph for sometime. There is no need to be stopped for 5 seconds. Low speed before 7 mph counts too.
     
    1 person likes this.
  8. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,166
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    It could be that I suppose. It happened today and I don't remember going under 7 mph with the ICE running, but maybe I did. I only really know for sure that I didn't stop.

    One other question on this. Sometimes when I've only stopped (car turned fully off and fob removed) for a few minutes, when I return to the car and continue driving I sometimes find I'm unexpectedly in stage 4. So I'm also wondering if it can actaully "remember" stage 4 provided that don't have the car turned off for too long?
     
  9. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,961
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Yea once the car is warmed up, the first ICE shutdown will get you directly into S4. I have not test it to verify it but it is much easier to get into S4.
     
  10. Hal W

    Hal W New Member

    Joined:
    Sep 26, 2010
    872
    53
    0
    Location:
    Grand Forks,B.C. Canada
    Vehicle:
    2006 Prius
    Model:
    II
    I think your car is going to EV mode as you come off the throttle, or is already in EV mode when you decide to slow down. In that case the ICE will be stopped when the car finally stops. Is that what you call the golf car stage? H
     
  11. 2009Prius

    2009Prius A Wimpy DIYer

    Joined:
    Mar 25, 2009
    2,701
    477
    63
    Location:
    USA
    Vehicle:
    2009 Prius
    My car drops out of S4 if the coolant temp falls below 157F and goes back into S4 if the coolant temp rises back up to 157F or above.

    If the pollution control stuff (cat converter etc.) cools down too much then the car would also drop out of S4 even if the coolant temp is OK.

    Hope this helps. :)
     
Loading...