Should We Let ICE Finish Warmup Before Shutting Down?

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by rorystewart, May 11, 2014.

  1. rorystewart

    rorystewart Junior Member

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    We've all been there: you run out of juice just before you reach your destination, causing the ICE to turn on.

    Question: is it bad for the car to turn it off before the ICE finishes its warmup (thus turning itself off automatically)?

    I've been in situations where I've sat in a parking lot with the engine running for a full 1-2 minutes before I leave the car because I'm worried that it's potentially harmful to the engine to turn it off before it finishes warming up. Any ICE experts here knowledgable enough to comment on what the best practice is? Sit in parking lot leaving ICE running or just turn it off even though the ICE has only been running for 15-30 seconds and hasn't finished warming up yet?
     
  2. GregP507

    GregP507 Senior Member

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    I'm not an expert, but the ICE is designed to run intermittently, not to maintain a steady output within a defined operating temperature range. The issue of operating temperature becomes much more important in much larger engines. This is due to potential warping of engine components due to higher thermal expansion differential within the engine. I've been running engines of all types for many decades in all types of climate extremes imaginable, and it's much more of a problem with larger engines than with smaller ones.
     
  3. 13Plug

    13Plug Active Member

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    I wouldn't and don't worry about it. I do that anytime (just shut it off)
     
  4. bisco

    bisco cookie crumbler

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    my only concern is the detonation some have had upon cold soak restart. for this reason, i let it run for a minute or more depending on outside temp.
     
  5. GregP507

    GregP507 Senior Member

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    Generally speaking, it's always a good idea to let an engine warm up before you put it under heavy load.
     
  6. El Dobro

    El Dobro A Member

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    If the ICE comes on, I let it run its course until it shuts off, it warms up fairly quickly.
     
  7. ny_rob

    ny_rob Senior Member

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    +1
    One time I didn't do that.. I got knock 0n startup the next day....
     
  8. -1-

    -1- Don

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    :confused:Makes sense, but if your traveling 60 mph in EV in the dead of winter and the ICE cuts on, I reckon it just has to "man up".
     
  9. mmmodem

    mmmodem Taste Tester

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    I think it's a waste of gas. I shut her off. I don't have any issues.


    iPhone ?
     
  10. rxlawdude

    rxlawdude Active Member

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    Who was there? :)
     
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  11. GregP507

    GregP507 Senior Member

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    "Knock-knock..."
    "Who's there?"
    "Pre-ignition."
     
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  12. ny_rob

    ny_rob Senior Member

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    Exactly! :p
     
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