Short trips? Here's a trick!

Discussion in 'Gen 2 Prius Fuel Economy' started by nooaah, Sep 19, 2008.

  1. Sheepdog

    Sheepdog C'Mere Sheepie!

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    I love it when threads get like this. Education on several different levels. New folks can learn, more established folks can learn, and more experienced folks can glean from Sages like Dr Fusco and the most honorable Ken San.

    If we could just get Dr Watanabe from Toyota in here.....
     
  2. N3FOL

    N3FOL Member

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    I have a trick for short trips. Put on my sneaker shoes and start walking for about a mile or two. It is not only good for the environment...it is also good for you. I am sure the doc will be happy with this idea.
     
  3. donee

    donee New Member

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    Hmm,

    Its 70 C (158F) for me before I can S2 glide. Then there are all sorts of shenanigans above that.

    Lately the car has been up to the mid 80's C, and it wont glide. Even after having been at multiple stop-lights. On my trip out doing errands yesterday, I was at 85 mpg, at 85 C (185 F), at about 12 miles into a 18 mile trip and then the car decided it was just going to run the engine. Outdoor temp was about 78 F. Being on a road I could not stop, it was down to 70 mpg, before I reached a residential area along my route, and did a stop/go. Then it was normal.

    This has also been happening on the way home. There is a long straight low traffic road that I like to glide about 7 miles out from work. About 70 % of the time the car will glide there, but the other times it wont. Temps are well up into the 80's by then.

    I have also noticed the thermostat opening around 80C. The temp drops down to just below 80 (78 or so) then comes back up. To get into S4, the temp needs to be above 80C apparently. If I am in a gliding portion of the route, the car will drop back into S3, and not glide after a glide.

    These situations are the reason I am not consistently exceeding 70 mpg. I am at 68.4 right now.

    Anybody have some insight that might help me out ?
     
  4. donee

    donee New Member

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    Hi All,

    I concure with Evan on the 35 mph S2 glide. I even have this in S4 glides when outdoor temps are below 40 F at the end of the morning drive.

    My stategy is to try to glide the most when the car is cold, to stay in S2. Then get through S3 very quick by timing it for unhill pulls prior to a stoplight I usually get caught at. Then into S4, but possibly with a fall back to S3 when the thermostat opens. After all this I am onto the highway and into SHM once the SOC gets greater than 60%. Which works out, because my initial highway is slightly uphill, which takes the SOC quickly up.
     
  5. nooaah

    nooaah New Member

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    Not possible when it's 4 miles round trip and you have about 30 minutes to get your errands done. :p
     
  6. darelldd

    darelldd Prius is our Gas Guzzler

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    Snotty-smug alert! You've been warned...

    This S-stuff is confusing. I prefer S5 that my EV allows. ICE off at start. ICE off at stop. ICE off at pulse. ICE off at glide. And S5 is so easy to get into! You just turn the key and away you go. Any temperature, any day.

    /snotty-smug.
     
  7. abq sfr

    abq sfr New Member

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    I think all the S#'s go out the window when the cat is not hot enough. I can have engine coolant at 184 and the ice won't shut down sometimes.... I figure to heat up the catalytic converter. You do a lot of gliding, or even P&G... and the cat cools down. Even when its not winter.
     
  8. GreenJuice

    GreenJuice Member

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    As temperatures fall, I've been able to experiment more at S2 as my Prius struggles to warm up on short trips. My initial experiences were that my European model seemed more similar to the US version, being unable to ICE-off glide until S4, but then I stumbled on something....

    If I turned off the interior fan (manually or by A/C AUTO off), I was able to ICE-off glide in S2 and the car's behaviour became exactly the same as Ken's 'Japanese Prius S2 behaviour is same as S4'! At S4 temperatures, any 'demand' for interior temperature comfort did not seem to affect ICE-on ICE-off behaviour.

    I wonder if this might contribute to explaining some of the different observations on this thread. If so, it might segue to a fuel efficiency lesson for short trips in cold weather - which is to wait till S4 before heating the interior :confused: (note that he's a bit blue..!)
     
  9. Bob64

    Bob64 Sapphire of the Blue Sky

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    I don't think thats correct.

    Typical commute: I don't use any air conditioning or heat (or fans).
    When I'm not in S4: Car ONLY glides (with ICE off) above 70c water temp and speed is between 35-41mph. If the water temp is below 70, it idles.
     
  10. warrior

    warrior New Member

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    Nihongo shabaru?:)
     
  11. GreenJuice

    GreenJuice Member

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    That's interesting - so its looking like there is a difference between the North American and European/Japanese versions of the NHW20 in the way they are programmed (I already know that we don't have a fuel bladder).

    Here is a picture about three minutes into this morning's commute showing my ICE-off glide in S2:
    S2 ICE-off Glide.jpg
    IGN = 5; RPM = 0
    57c water temp; 24 mph in no arrows glide on MFD.
    ICE also remains off when stationary.

    For other UK/European owners thinking about getting something like ScanGauge, I can confirm ICE-off glides work with engine water temps around 40c to 70c, and also as [email protected] indicated, when pushing the envelope into S1a using the EV mode.

    It is fascinating to watch this behaviour, say at 68c, and then only seconds later, as the water temperature rises just a few degrees, the car slips into S3 and the ICE simply refuses to cut until forced into S4 at the next stop - what was the genius behind programming that into the onboard computer?!

    I wonder if there is something else in the North American model that is setting the 'demand' for ICE in S2 - different catalytic converter perhaps? Possibly something optional, as we don't seem to need it over here.

    In any case, I'd like to take this opportunity to congratulate you on being able to get such great mileage despite having this handicap!
     
  12. Rest

    Rest Active Member

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    Interesting, I only get around 38mpg in a very hilly area with my tires at 50psi all around.
     
  13. van-island

    van-island New Member

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    That's shaberu. :)
     
  14. nooaah

    nooaah New Member

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    I'm down to 46-47mpg since the temperature hit the 30's. However, I did inflate my tires back to 42/40 and this is what happened when the temperature got a little bit warmer:
    [​IMG]

    It hovered around there until the temps dipped again, then plummeted.

    Anyway, the real trick to getting that kind of milage is to find a route that doesn't have frequent stops. I'm convinced that street route and terrain are the two main factors in determining your ability to consistently break 50mpg. I'm no hypermiler, by the way.
     
  15. Fred_H

    Fred_H Misoversimplifier

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    The heat storage thermos perhaps?
     
  16. donee

    donee New Member

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    Hi Fred H and Green Juice,

    What Green describes is the same behavior the NA Prius has. I do not think it has to do with the thermos, because, the thermos pumps the coolant into the block in during the first half of S1. After that the car is probably programmed the same way.

    The key to getting good medium (15 to 25 miles) trip mileage is to get a route where you have no stops during the first 2/3's of S2 and a speed above 35 mph. Remember, in S2 you need to be above 35 mph to get an engine-off glide. A stop in the last 1/3 of S2 will help to keep the car in S2 longer. Then during the first part of S3, its good to have an uphill followed by a stop. This gets one through S3 as fast as possible.
     
  17. dominicsavio

    dominicsavio New Member

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    Would someone be kind enough to tell me what the following denote:

    1)S1, S2, S3, S4...?
    2) "EV Button"
    3) EBH
     
  18. efusco

    efusco Moderator Emeritus
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    http://priuschat.com/forums/knowledge-base-articles-discussion/37699-priuschat-glossary.html

    1) The 4 computer controlled stages of hybrid operation. From initial warm-up (S1) to full hybrid mode (S4). S2 and S3 are limited hybrid operation.

    2) EV button--a standard feature on non-North American Prius and now on the Highlander hybrid as well. Allows you to extend the range of electric only operation of the Prius before the ICE kicks in.

    3) Engine Block Heater
     
  19. nooaah

    nooaah New Member

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    Ding.

    The Prius is absolutely a terrible "big" city car. My highway MPG no matter what is in the 50's. When I drive in downtown Philadelphia, I sometimes don't even break 40 MPG. While I can get to all battery if I let the car chill out for a few minutes after I start it up, I still don't get efficient acceleration in battery-only until several miles into the trip.
     
  20. jdenenberg

    jdenenberg EE Professor

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    Your problem is that a Prius must warm up before it can get good MPG (especially in cold weather). All cars get poor MPG in the winter, but it is even more noticeable in a Prius since the ECU is programmed to keep the ICE (Internal Combustion Engine) and the Catalytic converter at temperature to minimize exhaust pollutants. This causes the ICE to run more often in the winter than in the summer and lowers the MPG.

    JeffD
     
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