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When to Kick in ICE to Add Just a Few Miles Range

Discussion in 'Prime Fuel Economy & EV Range' started by mr88cet, Jul 16, 2017.

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  1. mr88cet

    mr88cet Senior Member

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    So, is the belief that failing to warm up all the way after it starts causes permanent damage to the engine causing this sound forever after, or does it just make that noise if you start it up again shortly thereafter?


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    #21 mr88cet, Jul 19, 2017
  2. bisco

    bisco cookie crumbler

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    just when you start it the next time. but no one has done a tear down to look for damage. it's unclear exactly what is happening inside the engine.
     
    #22 bisco, Jul 19, 2017
  3. mr88cet

    mr88cet Senior Member

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    Does this apparent effect go away over time, and if so, then how much time? In other words, does it seem to happen only if you re-start the engine, say, 15 minutes later, or can it be observed days afterward?


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    #23 mr88cet, Jul 19, 2017
  4. bisco

    bisco cookie crumbler

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    typically, someone has started their car, and moved it around on their property. maybe 30-60 seconds, then shut it down until going out the next day, and that's when it happens. but there have been many variations.
    there is a tsb for an updated manifold for the early gen 3's, but it hasn't proved very helpful.
    best remedy has been, 'don't do that!'
     
    #24 bisco, Jul 19, 2017
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  5. alexcue

    alexcue Active Member

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    Has anyone observed this on a Prime or Gen 4 for that matter?
     
    #25 alexcue, Jul 19, 2017
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  6. bisco

    bisco cookie crumbler

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    not that i recall.
     
    #26 bisco, Jul 19, 2017
  7. NJ-PrimeAdvanced

    NJ-PrimeAdvanced Member

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    Looks like Toyota addressed this issue? modern engines shouldn't really get into trouble, especially in a modern and tech-advanced car like the Prime... surely! :)
     
    #27 NJ-PrimeAdvanced, Jul 19, 2017
  8. mr88cet

    mr88cet Senior Member

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    My guess would be that other factors were at play...


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    #28 mr88cet, Jul 20, 2017
  9. bisco

    bisco cookie crumbler

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    yes, design errors that probably required throwing the baby out with the bathwater.
     
    #29 bisco, Jul 20, 2017
  10. mr88cet

    mr88cet Senior Member

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    Actually, now I'm thinking the best bet is to fire up HV mode right as you start up the car, on that won't-make-it leg of the journey (if you know ahead of time). Then, after the warm-up cycle, drive a little HV only during the faster parts of that leg of the drive.

    I suggest that because, if you take the warm-up-cycle hit, at a stand-still in Park, will charge the battery whereas, if the warm-up cycle hits while you're driving, it appears to keep driving on battery power until it completes. At least I presume it does, since that's what it did on our gen-2.

    So, you take the warm-up hit either way, but at least it charges the battery during the warm-up cycle rather than draining it!


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    #30 mr88cet, Jul 30, 2017
    Last edited: Jul 30, 2017
  11. mr88cet

    mr88cet Senior Member

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    I had to burn a few tablespoons of gas just now, so I tried this. Kinda works, but not quite: Unlike our Gen-2, the P.Prime does not immediately run the warm-up cycle if you switch to HV mode at a standstill (and BTW I think my stepdaughter's Gen-4 regular Prius is the same).

    They seem to have carefully designed it to make sure that the fuel burned in the warm-up cycle is for-sure wasted! Well, I'm glad it's at least shorter than the Gen-2, in part because using the cat to warm up the engine.


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    #31 mr88cet, Jul 31, 2017
  12. mr88cet

    mr88cet Senior Member

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    Actually, thinking back to it, the energy monitor, I believe, did show power going to the wheels during the warm-up cycle.


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    #32 mr88cet, Aug 1, 2017
  13. Oniki

    Oniki Active Member

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    My answer to OP: never
     
    #33 Oniki, Aug 3, 2017
  14. mr88cet

    mr88cet Senior Member

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    So, if you run out of EV range, the engine will kick in (unless you're it of gas too! ). The question is how and when to kick it in for just a few miles somewhere on that leg of your journey, to burn the least amount of gas during the few minute/miles when it is on.


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    #34 mr88cet, Aug 3, 2017
  15. bisco

    bisco cookie crumbler

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    if i know where i am, i kick it on just before reaching my destination. the distance depends on the weather, speed and hills. that way, it's off when i reach my destination, and the warm up has added enough ev to get me there,
    if i don't know where i am, i kick it on a little sooner, so i know it will be off before arriving.
    if gen 4 doesn't mind partial warm up, i suspect letting it come on after ev depletion is most efficient.
     
    #35 bisco, Aug 3, 2017
  16. mr88cet

    mr88cet Senior Member

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    On at least one occasion, I've seen it continue to run off battery power during the warm-up cycle, rather than the warm-up cycle adding power to the battery.

    Perhaps the trick is to, whenever you kick in the engine, and while it does the warm-up cycle, put it in charge mode...?


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    #36 mr88cet, Aug 3, 2017
  17. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    That is exactly what I routinely do ( for other reasons though - see my other post).
    Nevertheless from what I observed on the energy flow display it takes a while after engaging CHG mode to see the arrow indicating that traction battery is charging.
     
    #37 Krzysiek_KTA, Aug 3, 2017
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  18. Oniki

    Oniki Active Member

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    I understood your question. When EV ends, ICE begins. End of story
    I might feel differently in the winter cold but for now the ICE warm-up is fast and efficient.

    The problem with force charging is that you may be taking the Prime ICE out of its efficient ICE load to charge the battery. Left to it's own, the car is optimized to handle the warm-up. Without instrumentation you have little idea of how you are doing.

    The other problem is that you never know how many EV miles to reserve. Anything extra you arrive with was wasted; estimate too little and you go through the warm-up cycle twice.
     
    #38 Oniki, Aug 4, 2017
    Last edited: Aug 4, 2017
  19. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    From what i observed engaging CHG does not affect the warm-up cycle. Regardless of D, B or CHG mode the war-up cycle is managed by the car. That is what I observed.
     
    #39 Krzysiek_KTA, Aug 5, 2017
  20. heiwa

    heiwa Active Member

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    After driving my commute in different sequences of EV/HV I've come to the same conclusion as Oniki. My only concern is the long term battery health because I must be draining the traction battery well into the HV reserve when I turn the car off still in ICE warm up state. I never experienced ICE shaking next day start up as Bisco described.

    Another benefit of running in EV till EV range is out is that I often find myself making it home in all EV by turning off AC and fan at the precise moment.

    Posted via the PriusChat mobile app.
     
    #40 heiwa, Aug 5, 2017
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