Cruise Control Triggers ICE?

Discussion in 'Prime Technical Discussion' started by PiPLosAngeles, Dec 8, 2019.

  1. PiPLosAngeles

    PiPLosAngeles Active Member

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    I've been trying to narrow down the conditions, but when SOC > ~90%, engaging cruise control triggers ICE 100% of the time in my vehicle. I have carefully ruled out cruise control causing other conditions that would normally trigger ICE like excessive regen, going uphill, or acceleration. Setting cruise control on level ground at the speed I'm already going still triggers ICE every time. Of course, this initiates a warm up if I've been driving in EV for a while so I can't use cruise control until my SOC is below 90%.

    Is my car an anomaly, or is this "normal" behavior?
     
  2. schja01

    schja01 One of very few in Chicagoland

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    I use cruise control all the time and it does not trigger the ICE ever. I run in ECO EV exclusively.
     
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  3. Bob Comer

    Bob Comer Active Member

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    CC never triggers the ICE if it's in EV here on my Prime. No clue how it could!
     
  4. PiPLosAngeles

    PiPLosAngeles Active Member

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    Even when your SOC is over 90 - 95%? I can toggle CC on/off and the ICE goes on/off with it. Every time if the SOC is in the 90's.
     
  5. Bob Comer

    Bob Comer Active Member

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    I don't keep that close a watch on the SOC (State of Charge% full?), but mine only uses EV if I have enough charge.

    Perhaps are you doing it on an incline? (we're as flat as a pancake down here with slow speed limits.)
     
  6. jerrymildred

    jerrymildred Senior Member

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    It has never ever happened to me and I use cruise all the time when not in a residential area. At all SOC percentages right up to 100%. I can't imagine why yours would do that if it's in EV (not EVauto which can be unpredictable) and not calling for engine heat -- neither of which would have anything to do with cruise control.

    However! You are not the first to observe this. I did a little googling for you. See post #13 from this thread last year. Engine turns on randomly in EV mode | PriusChat

    It seems that temperatures under 50F can cause what you've experienced.
     
  7. PiPLosAngeles

    PiPLosAngeles Active Member

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    I suspect it's more nuanced. I think there's a relationship between SOC and outside temperature in deciding whether CC triggers ICE, but the "why" I have no idea. It's not strictly <50°F.
     
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  8. jerrymildred

    jerrymildred Senior Member

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    I don't think anyone really understands why that happens.
    171697_HeadScratchingEmoji.jpg
     
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  9. Skylis A

    Skylis A Senior Member

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    Normally I don’t use cruise at 45mph except to send a polite message to the tailgaters on backroads with 45 speed limits (obviously not the highway), this morning was one of those mornings...

    and about 20F outside, and my hybrid’s engine also stayed on until I switched from hybrid mode to EV mode. Confirmed with ScangaugeII, going uphill with cruise engine RPM stayed around or just below 1100 while the battery current went up to 80 amps.

    I still wish for Toyota to release a software update to address these nuances, or maybe a “here’s why your engine is still on” the HUD would be nice.

    Then again I’d like the HUD to display a reel of the latest sports stats, wishful thinking perhaps yeah
     
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  10. sam spade 2

    sam spade 2 Senior Member

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    "Can't" is not the proper word to describe this situation.
    ;)
     
  11. vvillovv

    vvillovv Active Member

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    I've never had cruise trigger ICE, although one difference is I'm very conservative at switching modes. I typically drive EV Normal probably 85% of the time - HV Normal 10% - ECO EV and HV 4% - Power EV and HV 1% estimated.
    I wouldn't go on and on about my beliefs of how the computers crunch the data and how I believe it effects the way the car behaves, because it's only my beliefs and they are just as prone to be wrong as right.
    Hope you figure out why it's behaving like that.
     
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  12. MarVel

    MarVel New Member

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    What is ICE- (I am a newbie)
     
  13. PiPLosAngeles

    PiPLosAngeles Active Member

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    If you want to drive in EV it is. If you stay in cruise control the ICE stays on. You will never deplete the battery below 90% to trigger actually driving in EV, or at least prolong the switch for a very long time.
     
  14. jerrymildred

    jerrymildred Senior Member

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    Well, either there's something wrong with your car or there is a condition that has never ever happened to me (or apparently @vvillovv and others) in the 15,000 miles that I've had the car. For example, at the end of the day, I unplug and hit the highway immediately. 45 mph limit, so I set the cruise at about 52 indicated, usually before the SOC gets below 98%. Day after day. Same with other driving conditions. Unless I drive beyond EV range, I can go for weeks without the ICE starting and use cruise control most of the time. The only time my ICE has started that I didn't expect was when I accidentally bumped the defrost "button."
     
  15. Salamander_King

    Salamander_King Senior Member

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    My daily commute does not have long enough stretch of road with high enough speed limit to use CC. But for a few occasions I was testing DRCC on my commute, I don't think it triggered ICE. I use CC when I am on an Interstate Hwy going ~65mph or above, and I am always in HV mode for those situations. I can test it later today on my way home.
     
  16. PiPLosAngeles

    PiPLosAngeles Active Member

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    That's what leads me to believe there's more to it than just SOC. The only other factors I can think of are temperature and speed, but I see it happen whether temps are in the 50's or 70's. The speed is usually around 65. Maybe a wild-assed guess, but if they reused code from the PiP, maybe that old 62 mph limit on EV driving is still there waiting to be triggered under some unanticipated scenario. I do not know.
     
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  17. vvillovv

    vvillovv Active Member

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    Man, that old 62 - 64 mph limit on the PiP was frustrating. Most 55 mph speed limit roads locally run around 65 to 70 consistently.
    The other was climbing hills on 35 mph limit roads where traffic ran near 55mph. Pushing up those hills from a red light was a sure way to trigger the ICE.

    Reminds me of Sammy Hagars " I can't drive 55"
    One foot on the brake one on the gas ----
     
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  18. Bob Comer

    Bob Comer Active Member

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    Have you ever hooked up a scangauge to read the codes? Maybe it's throwing some kind of error.

    There's a couple other things that effect whether the ICE runs or not, and one is the defroster, and the other is speed (over 80 somewhere, I haven't hit it so I don't know). Do you have a Prime that was bought in europe? I know EV is programmed a bit differently over there.

    I can definitely say my car doesn't do that, I start out from work and put my CC on almost immeditaly, with my charge as high as it can get and it never turns on the ice.
     
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  19. m8547

    m8547 Active Member

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    I had the cruise control trigger the engine yesterday morning. I was at 93% charged, going 47mph, and the battery was around 41 degrees. There's often a speed trap on this road, so I like to use cruise control to not worry about accidentally going too fast if I'm not paying attention As soon as I set the cruise control, the green EV light turned black, but the display still said 999.9MPG. Eventually it decided to do the warm-up cycle and start using gas. I've used the cruise control on this same stretch of road with higher SOC, but usually when it's warmer. I think low battery temperature is the main cause of this, besides high SOC.

    Later when I was on the highway and the engine had warmed up, I switched back to EV mode and had probably between 70-90% charge. I experimented with the cruise control, and each time I set it, there was a blip of negative power to the engine (engine braking) on Hybrid Assistant, and the EV light turned off. Since the engine was warm, it's more likely to use the engine in EV mode. But it makes no sense to have a blip of engine braking when I'm driving at a constant speed.

    I've also had the cruise control turn on the engine at a very low SOC (probably around 20%) when the battery is cold.
     
  20. jerrymildred

    jerrymildred Senior Member

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    I don't think it's speed unless you're up over the 80+ limit for EV, which would turn on the ICE before you had a chance to engage the CC. I very rarely drive EV at freeway speeds, but the times I've done it, the ICE never came on with or without CC. I guess I would have to deliberately experiment with it to be absolutely sure.
     
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