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Solved : Transistion to S4 without idle check.

Discussion in 'Gen 2 Prius Main Forum' started by uart, Mar 23, 2011.

  1. 2009Prius

    2009Prius A Wimpy DIYer

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    I tried it yesterday and it did not work. The car stayed in S3 after being turned off and back on quickly. The coolant T was 163F (high enough for normal S4). Maybe the coolant T needs to be higher for this "OFF->ON" trick to work? Or maybe my car needs the 5 seconds delay between the off and on as Ken said?
     
  2. uart

    uart Senior Member

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    Try it with a bit longer delay 2009Prius. This is pretty weird because I've been doing it now for several months so I know it definitely works. I've done it dozens of times and it hasn't failed me once.

    After you power off, make sure you wait until all the lights go off on the instrument panel (one to two seconds) then just hit he button again and wait for the ready "beep" (another two seconds).

    I don't have any way to measure the coolant temperature so I just do it after I notice that I'm in stage 3 (engine continues to run if gliding from below 55 km/h).


    Maybe the Australian Prius is different????

    Maybe the 2004 to 2006 models are different???

    Has anyone else tried it, let me know if it works.
     
  3. mikewithaprius

    mikewithaprius New Member

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    When the engine is running and I'm going very slow near a stop, the engine will do its idle ceremony and shut off under 6 mph it seems. Even if this takes a couple seconds, I prefer the momentum conservation, since I can be going 5 mph and then switch to EV for first part of acceleration.

    uart, question...

    I have to admit I'm not fully understanding something here - I think it might be holes in my comprehension of the stages.

    How could you know, if you entered into a glide over 55 km/h (34 mph), whether or not you entered that glide in stage 3 as opposed to stage 4? In both stages 3 and 4 you can enter into a glide over that speed. In other words, I see the point of the operation if the engine is running and you have to stop, but in the case you mention above, turning the car off and on while you've been slowing from an engine-off glide assumes stage 3 operation, which you can't know in that particular situation.
     
  4. uart

    uart Senior Member

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    Yes it doesn't need to be fully stopped to do the idle check but it does need to be going very slow (about walking speed in my case). In general driving the only time that I ever go that slow is when I'm stopping so it really makes no difference. Even if I could arrange the opportunity to drive at that speed at some point where I don't need to stop then the momentum "saved" would be negligible and the inconvenience of slowing to 5MPH in a situation where I didn't need to stop considerable.

    What I'm saying is it's a good strategy if you actually have some point in your trip where you really have to go 5MPG without stopping, but otherwise not so useful.

    Ok I'm not fully understanding either. When you start a glide from over 55 km/h then yeah you cant tell if you're in stage 2 or stage 3 or stage 4 because they all behave the same. Basically I just know I'm in stage 3 after I've driven long enough for the engine to be fully warm and if I haven't done the idle check yet.
     
  5. uart

    uart Senior Member

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    I should also point out one other thing that I've been overlooking in this discussion. In Australia UK Canada and most of Europe the Prius measures the instantaneous fuel consumption in L per 100 km. This actually makes it very easy to tell if the engine is still running when you're gliding.

    You see 100 MPG (US) is only about 2.4 L/100km, so that means in the US model you cant detect fuel injection if it's less than a rate equivalent to 2.4 L/100km. This means that if you're trying to glide but are in stage 3 with the engine idling, you may not notice it because the MPG's will probably stay pegged at 100 unless you're going really slow. With the Liters per 100 km units however we can see fuel injection basically all the way down to zero. So yeah I've kind of been overlooking that fact that not everyone can tell so easily if they are in stage 3 or stage 4, but trust me it is very easy if your Prius displays fuel consumption in L/100km.
     
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  6. uart

    uart Senior Member

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    Ok I just tested this again and paid close attention to exactly what I'm doing (I've been doing it so much lately that it's like second nature). I particularly paid close attention to how long I wait before restarting.

    When you come to a stop and hit the button to turn off, the speed and fuel gauge displays go off really quickly (about a second) but the gear selection display ( R-N-D-B ) hangs around for about another second and a half after that. So I'm actual waiting for all of the instrument lights (including the gear select display) to go out before I try to turn it back on. Maybe this is what you did differently 2009?
     
  7. mikewithaprius

    mikewithaprius New Member

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    Thanks uart :), it never occurred to me you could conceivably be in stage 3 an entire drive even with pulse and glide if you only start glides over 55 km/h or 34 mph - basically it'll act like stage 4 unless you are going slower, and only then you find out it ain't shuttin' off.

    That is very useful with L/100km and fake glides! Luckily with Scangauge now I can see RPM, so at 0 RPM I know the glide has succeeded.
     
  8. 2009Prius

    2009Prius A Wimpy DIYer

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    I probably didn't wait more than a second. I saw lights went off on the instrument panel but did not pay enough attention to remember if the gear selection light went off or not. I will give it another try and report back. Thanks!
     
  9. ystasino

    ystasino Active Member

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    I've been doing this for years, but the brakes make a whale/seal-like squeak so I'll try the two "P" methods listed here.
     
  10. reeed

    reeed Junior Member

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    yup. Technique works here in Singapore (2007 Prius, L/100km units), even if switched off <3 seconds.
     
  11. 2009Prius

    2009Prius A Wimpy DIYer

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    I tried in three occasions and the results were unfortunately less than spectacular. In all three cases I made sure that the gear selection lights were off before I turned the car back on.

    1. Coolant T at 158F which was just above the threshold. It did not work.
    2. Coolant T at 170s. Upon turning the car back on, the computer decided the T was high enough to run the CHS pump to store hot coolant in the thermos. As a result the coolant T got pulled down to 120s, thus not only S4 was not reached, but also S3 was lost. "Back to square 2".
    3. Coolant T at 180s. After the car turning back on and still at a stop, the engine automatically kicked on and did the idle check on its own. Neither time nor fuel was saved as compared to a normal idle check.
    It looks like either my car (US model) or my driving conditions do not allow the avoidance of idle check unfortunately.
     
  12. uart

    uart Senior Member

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    Thanks for taking the time to test it thoroughly 2009. That's a bit disappointing. It looks like the US model is different in this regard. I know that only the North American models have the coolant storage thermos, that seems to complicate the issue somewhat.

    I see above that "reeed" had no problems replicating the results in Singapore. I think that they have pretty much the same specifications as we do in Australia. I'm guessing that the UK and European Priuses would also be similar but we'd have to get some feedback from them to know for sure. So far we only know for sure that it works in Japan, Australia and Singapore.

    If anyone from UK/Europe or Canada can test this please let us know.
     
  13. spinkao

    spinkao New Member

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    Let me propose a different technique I've been using for a long time. If I stop at the lights in S3b and I am certain that the idle check is in order, but the engine is not running since I decelerated from more than 60km/h, I simply step on the brake with my left foot firmly and shortly stomp on the throttle. This fires the engine up, which than proceeds with the idle check as usual, transiting to S4.
     
  14. uart

    uart Senior Member

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    Yes I know about that technique spinkao, that's an old one.:) I used that before, but again it was frustrating because sometimes as soon as I'd kick the engine on the traffic would start to move and I'd have to drive off before the 10 seconds was up.

    This new method is faster and bypasses the idling altogether. I get more opportunities where I can reliably use this method than any other.

    Anyway it looks like it doesn't work for the US models. It looks like their startup/shutdown logic is different because of the thermos. Can you please test if this off/on method works on your Czech/European Prius.
     
  15. spinkao

    spinkao New Member

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    It works on my car. I noticed many times that if I power off the car in S3b and power it up again in a very short time, it would jump directly to S4. This often happens when I stop for gas at a highway, for example.

    I noticed many times that I can actually skip the idling ceremony by turning the car off and on again. However, it never occurred to me that I could do that intensionally while waiting on the lights ;).
     
  16. mikewithaprius

    mikewithaprius New Member

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    Just fyi, it didn't work for me today either, I gave it a shot with coolant plenty warm. I was decelerating with engine off in stage 3 from a glide over 35 mph. I also made sure gear lights were off before rebooting. Someone else above in Europe says it works - must be some weird US quirk like 2009Prius suggested?
     
  17. markderail

    markderail I do 45 mins @ 3200 PSI

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    Always stuck in S3...probably because a combination of the following factors :
    - winter wheels on Corolla rims
    - Sub-60f temps
    - heater on automatic set for 80f
    - no grill block