ICE running for a few minutes at start of trip on full charge?

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by mercat68, Oct 5, 2018.

  1. mercat68

    mercat68 Active Member

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    Over the past few weeks, I've noticed the engine kick in on my '17 Prime after about a minute when I'm underway on my morning commute. It runs for a few minutes and then goes back to full EV for the rest of the commute. The car's just over a year old and I don't recall it doing this until recently. Conditions are moderate/warm ambient air temp (60s - 70s), full overnight charge, moderate speed (30-40 mph). I've seen it do this in the winter, but only on particularly cold days and when I turn on the heater. Any idea why, all of the sudden, it's decided it needs to run the ICE?
     
  2. schja01

    schja01 One of very few in Chicagoland

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    If you haven’t run in hybrid mode for a long time it could be normal.
    I've "heard" it's to burn off stale fuel and/or exercise the ICE periodically.
     
    #2 schja01, Oct 5, 2018
    Last edited: Oct 5, 2018
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  3. priuscatprimeguy

    priuscatprimeguy Senior Member

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    When was the last time ice kicked in before this time? How many miles have you traveled total?

    Posted via the PriusChat mobile app.
     
  4. mercat68

    mercat68 Active Member

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    Thanks. My daily commute is about 33 miles one way total EV and about 28 miles EV / 5 miles hybrid on the return leg (overall uphill topography driving home, so less EV range). If I use it sparingly on weekends, I can go at least 1 month and often 1.5 months between fill-ups, so the ICE isn't getting a lot of use (I just went 2,227 miles between fill-ups). But it does run some (the daily hybrid portion of my commute home during the work week). Car has just over 20K miles total.
     
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  5. EyePrime

    EyePrime Active Member

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    Yeah, that happened to me too. I asked the dealer and as others have said on this forum is that the car doesn't want the fuel in the fuel lines to go bad so it has to run the ICE
     
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  6. mercat68

    mercat68 Active Member

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    Thanks - glad to know it's normal behavior.
     
  7. bisco

    bisco cookie crumbler

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    could be that slightly cooler temps are causing the battery not to accept early charge as you start out. any downhills in the beginning of your commute?
     
  8. mercat68

    mercat68 Active Member

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    About 400 feet of steep downhill driveway, then gradual downhill road for a couple tenths of a mile, then a steep uphill climb. I thought maybe the uphill climb was causing the ICE to kick in, but noticed it starts when I’m about halfway down the gradual decline before the big uphill.
     
  9. bisco

    bisco cookie crumbler

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    that might be it. but it didn't do it last fall?
     
  10. mercat68

    mercat68 Active Member

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    No, not that I remember.
     
  11. bisco

    bisco cookie crumbler

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    i don't agree on the burning off gas theory, because there is no mention of it in the manual, and few have reported it.
    and it wouldn't do it everyday, just if you had gone a long time without the engine starting.
     
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  12. VTBIGDOG

    VTBIGDOG Active Member

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    When the engine kicks on, are descending a hill with your foot on the brake pedal?

    Posted via the PriusChat mobile app.
     
  13. fuzzy1

    fuzzy1 Senior Member

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    Starting with a full battery?

    My first swag is that the battery starts by accepting some downhill regen, but can't take much before getting REALLY full, so must spin the ICE for engine braking.

    If you could stop the overnight recharge at something not quite full, leaving a bit more room to accept downhill regen, does this still happen?
     
    #13 fuzzy1, Oct 6, 2018
    Last edited: Oct 6, 2018
  14. mercat68

    mercat68 Active Member

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    Yep, @fuzzy1 , starting with a full battery. And yes, riding the brake down my driveway, but that’s maybe 10 seconds’ worth. Then, after turning onto the main road, minimal accelerator down the gradual decline. That’s when the engine kicks in. Although it might happen when I let up on the accelerator and regen starts (just before I hit the big uphill climb). I’ll keep a close watch on it Tuesday, when I head back to work and let you know in more detail what it does.

    I should add that my routine above is what I’ve been doing every work day the past year I’ve owned the car, but it’s only been doing this the past few weeks.
     
  15. fuzzy1

    fuzzy1 Senior Member

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    Not yet being a plug-in owner, I'm interested in how you got any downhill regen on a full battery. Maybe it always left a small buffer, and that has shrunk from some combination of aging and colder temperatures.

    Without some uncharged buffer, the engine should have spun up for engine braking almost immediately upon turning downhill and beginning regeneration. People living at the top of hills shouldn't be recharging to the fill line, but should stop a bit lower to leave some room for regen.
     
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  16. bisco

    bisco cookie crumbler

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    the software allows more regen on a full battery in warmer weather. of course, prius batteries are never close to full, so it is always a programming call.
     
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  17. VTBIGDOG

    VTBIGDOG Active Member

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    There are other posts on this site which describe the ICE coming on because the battery is fully charged so regenerative braking does not work. The ICE is coming on to assist with deceleration going downhill.

    I think this is normal behavior so I am not sure why it never did it in the past.

    Posted via the PriusChat mobile app.
     
  18. mercat68

    mercat68 Active Member

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    Update: Yesterday and today, the ICE did not kick in at the start of my commute. No change in road conditions or climate. Same time of the morning, same full charge, same use of accelerator vs. coast/regen. The only significant thing that has changed was that I took the car in Friday for the 20K service w/ oil change.
     
  19. bisco

    bisco cookie crumbler

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    probably the dirty oil, sounds like you're good now.(y)
     
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  20. mercat68

    mercat68 Active Member

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    Thanks. But to what end does the car run the ICE when the oil’s dirty? Just to circulate and keep sediment from building up?
     
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