ICE comes on anyway

I think you lost your "at"!! Sorry couldn't resist!!

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Something just occurred to me. Are you leaving it outside and unplugged?

 

I've not run into unexpected ICE firing up yet, except for once on a 30 degree night with the heat pump on at 74 degrees (too high) and the fan at level 5 (higher than normal), and charge level down to 9%. To me that was understandable as probable engine preconditioning. Didn't like it, but boom, there it was.

One week from now the high will be 18 and the low 8 degrees. I'm about to find out the lower limit of EV usage. Car will be left out (no garage) for more than 8 hours with various levels of charge, and unplugged. I usually don't have the heat turned on for my 1.5 mile trip to work. Maybe even turning the headlights or the radio on will be enough to trigger the ICE? Slowly decreasing temps until then.

Besides the lower temp tests in my normal usage, I might try the cruise control theory when it isn't 8 degrees. Note: at 8 degrees F the ICE should start anyway - or anything below 14, according to the manual.

 

Thing is, if the outside temperature goes below 14F and you need the heater, then the engine will turn on (page 87 of the manual). Of course, I would also expect that below this temperature, less current draw is available from the battery, so the engine may turn on. Perhaps this is an ideal opportunity to use Charge Mode so that gas is put to some use on very cold mornings, and then use electric on the way home. (Your mileage may vary, as they say.)

 

I'm thinking that freezing temperatures, lots of snow buildup, shoveling a path in the driveway, scraping ice off the back window and windshield is an excellent opportunity for Charge Mode usage. It can take 10 minutes or more to do those chores before driving off. The weather isn't at that point here yet, but give it a couple more weeks and I'll put full time EV mode behind me for the duration.

The L2 charge cable, which is outside, is already getting mighty stiff to move from the coiled storage position in these 20-30 degree cold night nights. I can't yet imagine what it will be like at 0 degrees F. Or I might not have to imagine since I'll be in HV mode 100% of the time.

 

Replicated the symptom the third time and captured on dash cam:

1. Fully charged and cold soaked at 40-41F (4-5C)
2. Was parked back ended, drove straight away, heater off
3. Several max accelerator and two stops
4. Accelerated to ~50-52 mph
   1. Use "," and "." to back or forward a frame
5. 1:47 -> Cycled cruise control: ON-SET-OFF (accidental OFF)
6. 1:49 -> Still in EV when hit SET and OFF (accidentally)
7. 1:54 -> Cycled cruise control: ON-SET
   
8. 1:57 -> Engine starts and runs, the heater was off and stayed off

Engine stopped about 5 miles down the road on its own. The heater did not come on by itself.

Bob Wilson

 

We really need to do A-B-A testing with enough samples to say ... 'we got it.'

It would help if others can replicate our results so we can map out the limits ... temperature, early operation (does backing out inhibit the symptom,) e.t.c. We really need a rock solid way to replicate the problem so we can document and teach Toyota how to do it too.

Bob Wilson

 

I use cruise control constantly, and I've never had this happen. I'm rarely at full-throttle, however. I suspect that was the culprit here, but not in the original case because it happened at almost no throttle.

 

Good work, Bob! Yes, we definitely need repeated A-B-A testing. People here on this thread don't seem to know much about problem solving (it's okay, most people in general suck at it). You can't just take it to the dealer and expect them to fix it. It is impossible to fix a problem that you cannot reproduce. They know that. They know that they do not have enough data. We are closing in on it here, though. Let's keep it up.

It's more than just cruise control, though. The formula seems to involve quite a few aspects, and something you are doing (or not doing) is still different from @priuscatprimeguy. We haven't found what that is yet.

You need to do what makes the ICE come on so we can be sure. I'm guessing you used cruise control with the rental car, no? If so, continue using the cruise control as you always do. Do it for two days in a row to be sure. Then try not using CC without changing anything else.

Anyone else who wants to attempt to reproduce the event needs to try to make as close to the conditions @bwilson4web and @priuscatprimeguy had. Make sure it's cold enough, below 50F. Park outside, overnight, plugged in, fully charged. Back in, so you drive straight out forward (I've been wondering for a few weeks if this might be critical) right away. In EV with heat off. Little or no hills (let's not introduce that variable if we don't have to). Speed up to at least 35mph within the first couple of minutes. Use cruise control.

Unfortunately, in spite of living in the appropriate climate, I am not able to try to reproduce this myself, for several reasons.

1. I park in my garage,
2. I drive in forwards and back out,
3. I live in a hilly area,
4. I have to drive quite a ways before I can go fast enough, even farther if I want a non-hilly place to speed up, and most importantly,
5. I do not (yet) have a Prime

 

i thought you stated the ice has also come on in the past without cruise.

 

Details, details, details!!

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I think we'd better call you Mr. Columbo, from now on!! Oh, and just one more question....!!

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Stubborn Sleuth; Dedicated Detective!