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

Fuel Consumption During Typical Warm-Up

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by JBumps, Jul 14, 2014.

Page 1 of 4
  1. JBumps

    JBumps Member

    Joined:
    Apr 18, 2011
    167
    57
    5
    Location:
    Morgantown, WV
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Base
    Thought this may have been previously covered, but no luck with various searches.

    Does anyone have any data on how much fuel is consumed during a typical warm-up period for the Gen III? I realize there are variables related to ambient temperature etc... just curious what information might be available from the collective PC knowledge pool.

    FWIW: my interest is to get a baseline consumption figure to compare warm-up saving devices/techniques against.
     
    #1 JBumps, Jul 14, 2014
    Last edited: Jul 14, 2014
  2. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,313
    3,588
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    There are more technical experts here (and many threads), but suffice it to say the the first 5 minutes approx. 25 MPG vs. 50 MPG normal.

    There was a electronic hack (not sure if applies to Gen3?) to speed up the warm-up.

    Keep in mind all USA Prii are CA_certified SULEV super low emissions vehicles. I am thinking if there were a non-SULEV Prius version available for non-CARB states, it might get better MPG during the warm-up. Possible that other hybrids (eg; FORDs) if not SULEV may have freedom for better MPG first 5 minutes.
     
    #2 wjtracy, Jul 14, 2014
  3. GregP507

    GregP507 Senior Member

    Joined:
    Apr 5, 2014
    3,002
    480
    0
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    I read somewhere that the Prius consumes approximately 1 gallon every 3 hours while idling. I've started mine in -20 weather, and it's warmed up in about 3-4 minutes, due to the exhaust-heat recovery system. I know that the engine runs more frequently in cold weather in order to keep the interior temperature up to the set level.

    I'm happy enough with my current fuel consumption, not to want to resort to driving around in the Canadian winter with the heater shut off.
     
    #3 GregP507, Jul 14, 2014
  4. JBumps

    JBumps Member

    Joined:
    Apr 18, 2011
    167
    57
    5
    Location:
    Morgantown, WV
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Base
    I have the thermistor hack you mentioned installed on my PiP.

    My data interest is not in the 'MPG' during this time, but the physical volume of fuel consumed by the engine to bring it up to standard operating temperature, i.e. start temperature to engine shutdown, without the hack activated. I can resort to Scangauge tests if no one is able to chime in, but I have a feeling some of the more tech savvy members here will be able to offer better info than I could achieve on my own accord.
     
    #4 JBumps, Jul 14, 2014
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,747
    48,962
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    two egg size containers full on a cold winters day. too much imo to allow the ice to start if preventable.
     
    #5 bisco, Jul 14, 2014
  6. GregP507

    GregP507 Senior Member

    Joined:
    Apr 5, 2014
    3,002
    480
    0
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    If you disable the warm-up programming, it could lead to premature engine wear, and condensation build-up in the crankcase.
     
    #6 GregP507, Jul 14, 2014
  7. JBumps

    JBumps Member

    Joined:
    Apr 18, 2011
    167
    57
    5
    Location:
    Morgantown, WV
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Base
    This is a unit of measure I'm not familiar with. Are these eggs large? Jumbo? Brown or white?
     
    #7 JBumps, Jul 14, 2014
  8. JBumps

    JBumps Member

    Joined:
    Apr 18, 2011
    167
    57
    5
    Location:
    Morgantown, WV
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Base

    The unit does not completely eliminate the warm-up cycle, but rather tricks the car into thinking it has completed the complete process, after reaching 114 degrees. It has been used by many on these forums with great success. To your concern regarding condensation - no UOA reports have indicated any measurable water content.
     
    #8 JBumps, Jul 14, 2014
  9. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,747
    48,962
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    :p good question. i would say average size chicken eggs. there's a thread here somewhere...
     
    #9 bisco, Jul 14, 2014
  10. GregP507

    GregP507 Senior Member

    Joined:
    Apr 5, 2014
    3,002
    480
    0
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Depends on the ambient humidity over a certain period of time, and the usage cycle of the engine. I've read postings in here which mention cloudy engine oil. Using it extensively in EV mode, and only allowing the engine to warm up briefly is a recipe for allowing condensation to build up in the crankcase. Allowing the engine to work at full operating temperature fairly regularly is good for the engine in a variety of ways.
     
    #10 GregP507, Jul 14, 2014
  11. rxlawdude

    rxlawdude Active Member

    Joined:
    Mar 31, 2011
    701
    219
    0
    Location:
    So Calif
    Vehicle:
    2015 Tesla Model S
    It depends on the henweigh.
     
    #11 rxlawdude, Jul 14, 2014
  12. JamesBurke

    JamesBurke Senior Member

    Joined:
    May 19, 2009
    1,222
    493
    27
    Location:
    Morgantown, WV
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    You could collect some data but then those might turn into Molotov eggs from the anti warmup/remote starter crowd if you do. El Captain John (john1701a) has some observation on this related to heater settings while driving in winter.
     
    #12 JamesBurke, Jul 14, 2014
  13. GregP507

    GregP507 Senior Member

    Joined:
    Apr 5, 2014
    3,002
    480
    0
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Styling mods are one thing, but modifying the computer programming is something else. Since the Prius is already the best at squeezing out more miles per gallon than any other car in its class, I think it's very presumptuous to think that simply reducing engine-run-time is something beneficial.
     
    #13 GregP507, Jul 14, 2014
    CharlesH likes this.
  14. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,691
    38,232
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Saying there's a hack that speeds the car's warm-up is a bit of a misnomer. It'll con the car into thinking it's warmed up sooner, and where does that go?
     
    #14 Mendel Leisk, Jul 14, 2014
  15. JBumps

    JBumps Member

    Joined:
    Apr 18, 2011
    167
    57
    5
    Location:
    Morgantown, WV
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Base
    Defending use of the thermistor hack was hardly the intent of this thread, but since you ask:

    Using it to speed warm up times prevents unnecessary engine run time (run time that wastes fuel by warming an engine that won't be called upon during the trip). Often times my trip could be completed without the engine coming to life at all, but temperatures may cause a start/idle. This mod works seemlessly for this purpose and was designed and tested throughly. In two years of use (in two different cars), I've had no issues whatsoever.

    Again, the point in asking this question to the masses was not to stir debate on the use of certain mods, it was to get a baseline fuel consumption reading against which to compare the effectiveness (fiscal effectiveness, i.e. is the installation and use cost effective) of using an engine block heater. Our neighbor's son needed an experiment for a school science project and I'm helping him out.
     
    #15 JBumps, Jul 14, 2014
  16. GregP507

    GregP507 Senior Member

    Joined:
    Apr 5, 2014
    3,002
    480
    0
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    But at what cost?
     
    #16 GregP507, Jul 14, 2014
  17. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,691
    38,232
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I'd suspect you could get away with a modest shortening of warm up behaviours; there's a buffer. Still...
     
    #17 Mendel Leisk, Jul 14, 2014
  18. KV1955

    KV1955 Member

    Joined:
    May 27, 2014
    49
    36
    0
    Location:
    Manassas, VA
    Vehicle:
    2014 Prius Plug-in
    Model:
    Plug-in Base
    No one else is gonna let you say it. So.....what's a henweigh?
     
    #18 KV1955, Jul 14, 2014
  19. rxlawdude

    rxlawdude Active Member

    Joined:
    Mar 31, 2011
    701
    219
    0
    Location:
    So Calif
    Vehicle:
    2015 Tesla Model S
    Oh, about two pounds. <drum roll-cymbal hit>
     
    #19 rxlawdude, Jul 14, 2014
  20. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

    Joined:
    Jun 21, 2009
    2,938
    2,288
    0
    Location:
    Silicon Valley
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Cold day: a chicken egg or two
    Hot day: hummingbird egg or two

    Mike
     
    #20 3PriusMike, Jul 14, 2014
(You must log in or sign up to post here.)
Page 1 of 4