Sudden hard acceleration starts ICE, but it won't turn off - why?

People say it will run to lubricate the engine for 10 minutes or so. OK, but how about 20 minutes or more? I agree, it is a software bug not affecting everyone. And if it isn't a bug then it is engineering malfeasance.

Tim

 

I am new to Clarity so I certainly won't try and armchair problem solve, but I did spend years of my former life troubleshooting software. I would caution against assuming that everyone is experiencing the same issue. I'm not saying anyone is but it's easy to do, I certainly did it myself many times. One thing I learned is that if someone says "I have the exact same problem" it probably wasn't. There is usually one or maybe two problems with fairly specific symptoms, and a handful of people who have that specific problem. Then a bunch of other people who have similar but slightly differing symptoms. Often those people only see the "problem" once or occasionally which means they probably have something else going on, either a different cause/effect that can sometimes happen, or a mysterious to us but expected behavior, or the occasional "glitch" that computers like to do just to remind us that they are in charge.

Reading through these posts it seems there are a few people who clearly have a problem, they have a set driving routine that in the past was almost ICE free for much of it, and now on a persistent and consistent basis ICE runs for long and unexplained periods of time. I would recommend continue to concentrate on those people (as you seem to be doing already) and put on a shelf for now seemingly similar symptoms that others (or even everyone) experiences on occasion, as those may be unrelated as similar as they seem.

Even among the persistent there may be differences, which could mean there are two or more different problems, or it could be that the same problem manifests differently. I am interested in ClarityBill's "SOC chasing" theory. I like theories that be proven or disproven, as either result helps move the ball down the field. The theory is that the computer fixates on a particular SOC and is determined to maintain that SOC even though you are not in HV mode. Perhaps the erroneous target SOC is not the same on each trip, but the consistent symptom would be that it seems to chase an SOC. If people with the problem could watch for that, if one or more people find that to be true at least much of the time that would help isolate what is going on, at least for some people.

Tim66 seems to experience that it is clearly related to going past the detent. That could be a clue, assuming Tim66 uses Normal or Sport mode, maybe those in Eco mode could try Sport mode and see if going past the detent causes the problem. Maybe Tim66 can check if he exhibits SOC chasing, which may take several trips to determine. The more data the better. Or maybe Tim66 has a different problem that happens to have similar symptoms.

I am also interested if clearing memory by disconnecting 12V fixes the problem even temporarily for some or most of the people with persistent problems. If it does fix it even temporarily that points to data that is somehow getting corrupted. A software bug would still be the root cause but it helps programmers tremendously if they know that the problem is in the data.

I hope I am not muddying the waters, I don't want to add complication, just some things to think about as you sort through a maze of various symptoms and try and piece together a coherent description of the problem(s).

 

There is no EV Only mode in the Clarity. EV Normal mode can and does use both power sources so to me this isn't a bug.

And that's another opinion.

I'm thinking the engineers are using this software logic: If the ICE is going to come on (for whatever reason; known or unknown) and go through a long warm up cycle, then it is more efficient to keep using it at its peak operating conditions rather than shut it down for rest of the trip only to possibly have it come on again much later during the trip when it has cooled and have to go through another warmup cycle. Warmup cycles are the worst case scenario for both mpg's and emissions.

 

So today, I tried to replicate the problem. Hammered the accelerator and the ICE kicked on as expected. However this time, it shut off after about 10 minutes (which most people think is the expected behavior) and it stayed in EV mode for the rest of my commute. I lean towards the bug theory.

 

I lean to not a bug. The engine ran for a longer period of time and now doesn't because it has satisfied the "need to run longer because it has been a long time since I ran the engine for a longer time period" requirement which is exactly how the car is intended to act.

The logic that X amounts of months has gone by without the engine running so now that it runs something must be wrong is flawed logic. That is exactly why it is running. We know this; it has been discussed and discussed often. If you do not run the engine in these cars for long periods of time then after a period of months it will start to run more and longer. We do not know the exact schedule or triggers but there are likely several that go into a formula such as: date of last time the engine reached full operating temperature, amount of time engine ran last, average age of fuel, etc.
Also I am not convinced the logic is such that one event of running longer will satisfy the requirement. If may want to run some number of times within a certain period until it meets some criteria. Unfortunately we don't know. The real flaw is Honda not sharing more about how the logic works on these cars.

 

@bbct,
It is not often that I have accelerated hard enough for the engine to start but I do recall thinking it took a very long time to turn off but it did eventuality turn off. I am willing to do some experimenting and report back.

 

Adding my recent experiences. After owning the vehicle for seven months and never having this problem, I experienced this issue three times last week. Car was at full charge in eco mode only a few minutes out from my house and on flat roads at around 40mph. Weather was 70F. No hard acceleration. The engine did not run for the ten minutes that we have previously speculated was needed to warm and lubricate the engine, it only ran for a like a minute each time and probably 4x each trip. It’s not to keep the gasoline fresh because I occasionally need to use fuel. I can’t explain why.


Sent from my iPhone using Inside EVs

 

This was most likely a System Check as described on p 13 of the manual.

Note that during a System Check:

-The engine may periodically turn on and off. This is normal.
-The curved blue line on the Power/Charge Gauge will not appear. (EV indicator may still turn on)
-Engine will run until operating temperature is reached.
-The curved blue line will reappear when the System Check is completed.

P 13 also lists 5 circumstances when the engine may turn off or if already on, may not turn off.

1 going uphill or accelerating aggressively.
2 Climate Control is in heavy use.
3 Ambient temperature is too hot or too cold.
4 The High Voltage Battery state of charge is very low.
5 The vehicle is running a System Check.

IMHO, this page explains most of the complaints about “unwarranted” or unexpected ICE operation.
On my Clarity which is driven 90% plus on battery and up to 8 months between HV trips, the infrequent and brief ICE runs haven’t even cost me a bar on the fuel gauge. So I don’t begrudge the computer deciding to occasionally run my ICE, since it keeps it healthy, ready for when I need it, and costs next to nothing for the year.

 

The system check is a valuable piece of information, thanks for letting us know. But in my case where I've had almost constant ICE engagement over more than two weeks now, I'm in CA and it's 50-60F so #3 doesn't apply, the battery is always more than 50% so #4 doesn't apply, CC is off so #2 doesn't apply, it's happening on flat ground and I'm careful about avoiding aggressive acceleration so #1 doesn't apply. I find it hard to believe it has been doing system checks every day for 14 days but I'll keep an eye on the power gauge to see if the blue line disappears.

 

@KClark, have you tried the disconnect of the battery to reset / clear data to see if that helps?

 

Not yet but I will, maybe this weekend.

 

I got my Clarity Touring at the end of November, and have put about 6K miles on it to date. The "a1 service" message just appeared a couple of days ago, so I'll be taking it in shortly and plan to ask about this issue as well as make sure that any/all updates and service bulletins get applied. I really have no idea what, if any, updates were applied to the car before I got it, so I guess I'll find out!

 

Well in my case, due to my travel patterns, the engine runs at least once weekly for at least 10 minutes, and in fact a few days before the event, I neglected to plug in the charger before heading to work and ran on gas for my entire 40 minute commute. So I doubt this is a case of the engine running because its been dormant for an extended period of time. OTOH, who knows what Honda uses for an algorithm. Could be they require some minimum monthly run time that my 10 minutes a week wasn't satisfying. Could be a bug. Who knows.

 

Don’t know if anyone’s mentioned this in the thread, but there’s a bug that will prevent the arc of the “power meter” from switching back to blue if you engage the gas engine via the petal. For people experiencing this problem, I would recommend verifying that the engine is actually on via the power flow display on the dashboard or main screen. Could be that your ICE did, in fact, turn off after warming up.

 

@bbct and others,

My test this morning @ 55F & full SOC. Clarity is just over 3 months old, very low miles so far.

As I left my neighborhood I floored the accelerator. Engine started and ran for about 13 minutes. I switch to between Eco, Sport, Normal (no Eco/no Sport) a few times. Mostly sport in the first 5 to 7 minutes and all Eco in the last 3 to 5 minutes. I did not touch the HV button.

 

BINGO!

 

I did another test. I was on the highway well beyond the battery range therefore the engine had been running often because the battery was depleted. The car was effectively in HV mode even though I didn’t use the HV button. So floored the accelerator and built up some speed with help of the engine then let up on the accelerator to coast. The engine shut down right away.

 

I wondered about that when the ICE would not shut off after a quick acceleration. Was the ICE really running or was the arc just not returning to blue. So I would switch the information display to the power flow display and the ICE was indeed on and supplying power to the battery and or front wheels depending on the SOC. More telling is when I come to a stop you can hear and feel the engine running even though the large display shows the ECO mode.

Tim