Drop out of S4 for no apparent reason?

Discussion in 'Gen 2 Prius Technical Discussion' started by 2009Prius, May 20, 2011.

  1. 2009Prius

    2009Prius A Wimpy DIYer

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    This does not happen every time, only very occasionally.

    Not sure how to detect/monitor EVAP purging. Any suggestions?

    HV battery temps climbed from low 20s (C) to near 30C during the entire trip.
     
  2. planetaire

    planetaire Plug in 20 kWh 85 km/h or > 208km range

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    Hello, 2009Prius.

    For evap you can try these pid:

    7e0 02 21 2E response=purge in byte 3
    7e0 02 21 32 response=vapor pressure in byte 3

    But unlike all pid's i give, i never use them. Then they are not sure.

    I look at your graph and specially this one:
    [​IMG]

    Did you look at fuel injection also ? May be this could help.

    What i think strange is, at 810sec, your ice stop ! Why ?
    You were pressing the accelerator pedal and your car have a speed over 10 km/h (6 mph).

    It look's like a iddling cancel but the speed was too low !

    If you would have leaved S4 before for some S3 state, your engine won't have stopped.

    I never saw such phenomenon in my Prius. (Note that we don't have thermos, tank bladder...) Only two way to leave S4:
    -during driving engine becoming too cold because a long glide or
    -when my ice do his "dance" i stop the car, press power-off and power-on. If i don't wait at least half a second between off and on S4 is not reached.

    About catalyst temp note that there is a threshold near 350°C (The one you call cat1).
    Ice temp threshold 40°C is more known. But when starting with an ice under 40°C and not totaly cold, the prius will stop her engine when the cat is in temperature.

    I think the prius nead that ice be over 40°C AND cat over 350°C in order to stop engine.
    If you start with an outside temp under about 20°C the cat will be over 350°C when engine reach 40°C and stop.
    If you start over 20°C the engine will be over 40°C when cat is at 350°C.

    A bientôt :)
     
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  3. guinness_fr

    guinness_fr Junior Member

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    Maybe I'm reading the graph wrong but it seems to me that this mostly happens with the SOC being over 78%, am I wrong?
    In my 2010 Prius I noticed that the mpg indicator sometimes shows fuel consumption when I reach a SOC of over 78% and I am slightly depressing the gas pedal (where I would expect to run on 100% elec only instead of using gas).

    Slightly off topic but I also encountered some cases where S4 enters late in the game (because I was driving faster than min speed required for Idle check ceremony) and a couple of times it would take much longer than the usual few seconds without gas input for the check ceremony to end. I've not been able to detect what causes this...
     
  4. 2009Prius

    2009Prius A Wimpy DIYer

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    Thanks! I will give it a try.

    I have the passive data. I will take a look.
    Yes this is exactly what's puzzling. The ICE would not stop for no apparent reason, and then it would stop some time later for no apparent reason either. So it seems the car had mysteriously left S4, and then it mysteriously came back into S4.

    It's harder to avoid the S4 dance by turning the car off then on for the American model. I tried and failed in several occasions. Sometimes the thermos pump would come on to pull down the ICE temperature. Even when everything was fully warmed up the ICE would turn on after the car was turned back on, similar to the initial warm up when the car was turned on cold.

    Thanks for the info! Now I wonder if I could come up with a heater for the cat in addition to the engine block heater.
     
  5. 2009Prius

    2009Prius A Wimpy DIYer

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    Sorry the color may not show up well on your screen. The SOC is the pink curve that's around 60% or slightly below. You may be looking at the engine coolant temperatures (iceT, wT, wT2). They are the red curves and well over 70C.

    I am not familiar with gen 3 Prius. Let's wait for others to comment.
     
  6. 2009Prius

    2009Prius A Wimpy DIYer

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    Well I have been living with the S4 dropout phenomenon and grown used to it and learned not to pay too much attention to it. There aren't really many good places to stop temporarily so I just keep going until it goes away.

    Today I had a chance to try something similar but not exactly the same. I stopped by the dealer's parts department to pick up some washers. The car hadn't dropped out of S4 before I turned it off. It sat in the parking lot for about 5 or 6 minutes. Soon after I turned the car back on (and before the engine kicked on) I shifted to drive and started moving. What I found was that the car still went through S1, but after that it went into S4 without the idle check. See this graph of collected data for more details:
    [​IMG]
    The transition from S1 to S4 can be clearly seen around time mark 2880 sec, when the HV battery stopped supplying power and instead to be charged (green curve), the power from the ICE jumped up (red curve), and the ignition timing also jumped up to normal operation range (purple curve). And there were no idle check as the speed was way over the limit for idle check (black curve). After that transition we see RPM drops to zero when gliding (orange curve).
     
  7. 2009Prius

    2009Prius A Wimpy DIYer

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    Long time ago we were asked about fuel injection and Evap data and I finally got around to plot it up:

    [​IMG]

    We see that during the S4 dropout it does burn some fuel (red curve). I can't see any correlation with the Evap signal (thick orange curve). Interestingly the ignition timing (green curve) is fixed at 10 during the S4 dropout, same as the value during idle check I think - may not be a coincidence. :cool:
     
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