Cruise Control Triggers ICE?

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

  1. m8547

    m8547 Active Member

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    I experimented with this some more. Last night with a warm battery and <90% charge I turned cruise control on and off numerous times, and it didn't seem to trigger the engine or do anything unusual. I tried DRCC with a setpoints below and above my speed, with and without cars ahead of me, and it didn't make much difference. I also tried standard cruise control (hold the cruise control on/off button for 3 seconds to activate), and there was no significant difference there.

    This morning with the battery at 50 degrees F and 98% charge, cruise control instantly turned on the engine. I was surprised it happened with the battery relatively warm. After the engine warmed up, I switched to EV mode and each time setting the cruise control turned on the engine. The behavior was the same with non-DRCC, so that's good I guess. As soon as I dropped below 90% charge it stopped turning on the engine.

    I definitely did see a blip of engine braking on Hybrid Assistant one of the times, but I was mostly watching the road and the EV light. I'll review the Hybrid Reporter graphs and see if I can find anything interesting. During that engine braking, the car didn't actually slow down, it was just the engine braking against one of the motors, and the overall power output was roughly coasting.
     
  2. PiPLosAngeles

    PiPLosAngeles Active Member

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    Even if engine braking is triggering ICE, I don't understand why it stays on when it's already warm and there's very little or no acceleration.
     
  3. vvillovv

    vvillovv Active Member

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    I know for sure, the Prime doesn't always behave the way I think it's going to or should. The only other suggestion I can think of ATM is try regular cruise instead of dynamic cruise to see if the car behaves the same, if you haven't already done that. Or try setting cruise at it's bottom end (28 mph dynamic ) while feathering the go pedal as you set cruise. Than raise to your desired speed using the stick and watching the MID and speedo at the same time. And get a feel for how the computer handles that.
     
    #43 vvillovv, Dec 24, 2019
    Last edited: Dec 24, 2019
  4. PiPLosAngeles

    PiPLosAngeles Active Member

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    I had it trigger at 53°F and about 95% SOC the other day.
     
  5. PiPLosAngeles

    PiPLosAngeles Active Member

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    Welp, it's now triggered itself on level ground cruising at constant speed at a cozy 76°F so I'm thinking cold isn't a necessary factor. I also tested DRCC vs. standard cruise control and there's no difference - ICE toggles on and off when speed is set/canceled.
     
  6. Bob Comer

    Bob Comer Active Member

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    That's so bizarre. How are you determining the ICE is on?
     
  7. PiPLosAngeles

    PiPLosAngeles Active Member

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    The little EV light in the HSI goes dark.

    In other words, this:
    [​IMG]

    Instead of this:
    [​IMG]

    Except in EV mode.
     
    jerrymildred likes this.
  8. Bob Comer

    Bob Comer Active Member

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    That looks like a bug to me. Change your main screen to the one with the car and electric flow on it, you can see if the engine comes on with that. (or the main EV light just to the left of there.)

    I did some testing the other day but couldn't ever get the engine to come on by those displays, but I never look at the one you're looking at. (I use the HUD instead and I don't think that shows that little car.)

    I'll see what that indicator says next drive...

    Anyway, I still think it's bizarre, and it shouldn't do that!
     
  9. Bob Comer

    Bob Comer Active Member

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    That little car stays EV for me as quick as I can get to it, as the cruise control screen overlays it when I turn it on or change speeds, so I have to press the back arrow to see the HV display quicker.
     
  10. m8547

    m8547 Active Member

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    It sounds like the engine isn't coming on for you. If it does, it will stay on for a while until it warms up. It's most likely to happen when the battery is cold (<40 F) and >90% charged, but it can happen other times too. Note that if you drive regularly the battery is probably always 10-20 degrees above the outside temperature, even the next morning, and if you plug in overnight the battery heater will keep the battery between about 34-37F minimum.

    Hybrid Assistant confirms that the engine comes on when the EV "light" goes off. Sometimes the engine is on even if there's no power flowing from the engine. In rare cases the engine might be on for a short time even when the EV "light" is on, but it's not common.
     
  11. PiPLosAngeles

    PiPLosAngeles Active Member

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    Thanks for this. It hadn't occurred to me to test what other screens were reporting. It turns out there is a bug, but it's not in the HSI ... it's in the Energy Monitor. While switching screens at a stop light with ICE running the Energy Monitor screen indicated that the engine was not running. That means either the engine is running and no charge is being sent to the battery, or that the Energy Monitor has a bug. Either way, I think it's a bug.

    The screen appeared like this while the engine was definitely running (you could hear it running).
    [​IMG]
     
    #51 PiPLosAngeles, Feb 25, 2020 at 9:57 AM
    Last edited: Feb 25, 2020 at 10:02 AM
  12. m8547

    m8547 Active Member

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    Often while the engine is warming up it's just idling, so it's not charging the battery. So no power flow is shown on the energy monitor screen. It would still be helpful to have it indicate if the engine is running or not.
     
  13. PiPLosAngeles

    PiPLosAngeles Active Member

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    Interesting. Since the HSI shows the engine running and the Energy Monitor shows no power transfer during these cruise control-triggered episodes it seems as though the bug is in the car thinking either a warming cycle is needed, or that there's excess energy that needs to be dissipated by running the engine. I don't believe it's the former since I see this even when ambient temperatures are near 80°F. That leaves the "excess energy" option.

    This is particularly interesting to me as a semi-professional bug hunter in other software. The Energy Monitor tells as that the battery is not receiving any energy input, yet the car's control system thinks there's extra incoming energy that needs to bleed off. If we could just cross reference the inputs to the Energy Monitor with the inputs to the engine control decision matrix we'd likely find the bug in the discrepancy between the two.

    EDIT - I have a suspicion that engaging cruise control also engages "B" mode, which would explain triggering the engine to bleed off power.
     
    #53 PiPLosAngeles, Feb 25, 2020 at 11:04 AM
    Last edited: Feb 25, 2020 at 11:49 AM
  14. m8547

    m8547 Active Member

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    The energy monitor is just a dumbed down cartoon representation of what's going on. Hybrid Assistant shows much more detail (actual power levels for the engine and motors) and updates much faster. I've noticed that setting the cruise control causes a short blip, less than 1 second, of engine braking sometimes (negative engine power), for some reason. If the engine is cold and it runs even a little, the car will complete a warm-up cycle. I don't like the engine coming on, so I haven't experimented with this too much to find the limits of conditions when it will or won't start.

    I think the engine coming on is definitely a bug. But I don't think the car provides enough information for us to troubleshoot the bug. Hybrid Assistant is a little more helpful, but without knowing why the engine comes on in the first place we might never know why this happens.

    During the unintended acceleration scandal, it was revealed that there were millions of lines of "spaghetti code" in the car's programming. I think it's safe to say that Toyota doesn't have the best software. Their infotainment systems are further evidence (even if they are probably done by a different team).
    Toyota Unintended Acceleration and the Big Bowl of “Spaghetti” Code | Safety Research &amp; Strategies, Inc.
     
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