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

Discussion in 'Clarity' started by bbct, Apr 16, 2019.

  1. bbct

    bbct New Member

    For the most part I really love my Clarity. Most of the things it does make sense to me. On this though I'm stumped. I was getting on the highway, had to hurry, and floored it. The ICE kicked in to help, and all went well. I was in EV mode, and it remained in EV mode on the display, but the engine kept running and running and running. I tried switching from EV to HV and back. This happened a second time, and off the highway I actually parked, shut the car off, turned it back on, and continued my drive. I had 20 miles of EV left, but the engine ran and charged the battery right up until I parked in the driveway and turned it off.

    Is this a bug? Sure seems like one. If nobody can offer a good explanation, I'll ask my dealer to look into it. I can understand the engine kicking in at that time of need, but as soon as I let up on the accelerator, it should go back to "normal" and act according to the selected mode.

    Has anyone else experienced this? I've only maxed the power twice, and it has had this same effect both times.
  2. Walt R

    Walt R Active Member

    Once the ICE is on, it will run until it is fully lubricated and warm - about 5-10 minutes. It should be for the health of the engine, since repeated cold starts would be bad for it. Also, the engine will behave a little better if, when you know you'll be using it, you turn it on during steady cruising or light load, instead of triggering it immediately into providing significant power.
    KentuckyKen likes this.
  3. bbct

    bbct New Member

    Walt - while that sounds feasible, I don't think that is the case. It happened again today. I had over half a charge, about 23 mile EV range. I got on the freeway, and the ICE kicked on the same way I originally described. It would have run the whole way home, but I was pushing buttons trying to get it to turn off. At a light, I put it in HV mode. The blue line showed up and the engine shut off. I started moving slowly, still on electric, the top icon said Ready EV. I pressed the HV button to turn HV mode OFF (which should put me in pure EV mode, I've got plenty of battery). Instead of the blue line extending further, it disappeared and the engine turned on. I put HV mode back on, the blue line appeared and the engine shut off. The entire rest of my drive, when HV mode was on and I was hardly accelerating, Ready EV showed and the engine shut off. But every time I turned HV off, the blue line would turn all white, it would say Ready (no EV) and the engine would start up again. This was the case for my entire 15 minute drive home. When I stopped to park the engine was running, charging my battery. It burned very little gasoline, but my range on fuel came down a couple miles. I think I'll call the dealer and ask if there is some sort of software glitch they know about.

    I cannot think of any reason, with over half a battery charge, that turning off HV mode should turn ON the engine under virtually no load, especially when the engine started out OFF in HV mode.
  4. vin seeram

    vin seeram Member

    Though the Clarity ICE behavior is still a little bit of mystery, there are known scenarios when ICE turns on to protect the car, as explained in many threads. I'd suggest you observe for a few days without fiddling too much with the modes, or turning the car off and on to turn off ICE.
  5. KentuckyKen

    KentuckyKen Well-Known Member

    Let me preach alongside @insightman and reiterate that there is no pure EV mode selectable or otherwise available in the Clarity.

    When you try all those machinations to turn off the ICE, all you are probably doing is interrupting the programmed cycle which will cause it to keep turning on the ICE as it tries to complete the programmed cycle. Just let the ICE run because the vast majority of reports indicate it will turn itself off after it reaches operating temperature and that’s exactly what mine does. My Clarity has gone 9 months between out of town HV trips and the occasional ICE runs haven’t even cost me one bar on the fuel gauge.

    So enjoy almost all EV driving and don’t sweat the occasional ICE runs.
    You and your Clarity will be much happier.
    dnb, 4sallypat and ClarityDoc like this.
  6. KClark

    KClark Active Member

    I was going to post my own Clarity head scratching experience with ICE. I’ve had my car 4 months and except for one long trip I’ve just commuted with it, 44 miles round trip. Up until about a week ago I did all of that in pure EV. So when my ICE kicked in last week on my way to work with 75% charge I thought that maybe after almost two months of pure EV driving it was time for it to do that. But every day since then the ICE has started on my commute, sometimes each way. I always have plenty of charge, I can’t figure what has happened in the last week to cause it.
  7. fotomoto

    fotomoto Active Member

    You may have reach a fuel maintenance mode (FMM) if you've been nearly 100% EV for 4 months. PHEV's typically engage this mode to burn off gas at the rate of a tank/yr if it's not being driven in HV. So the computer may stay in the mode till it burns off "x" amount of fuel. I don't know specifically about the Clairity tho'.
    ken wells likes this.
  8. KentuckyKen

    KentuckyKen Well-Known Member

    Good speculation but I don’t think the Clarity has the FFM that the Volt does.
    I say that because mine has been happy to let my tank of gas sit there for 9 months without losing a bar on the gas gauge. I do get a few very occasional and short ICE runs that I attribute to the System Check of page 13 in the manual but it certainly is not trying to burn up an appreciable amount of gas like the Volt.

    So I don’t think it acts like a Volt that is programmed not to let gas sit in the tank more than a year. (Told that by a Volt owner/not seen in a GM source doc)
    ClarityDoc likes this.
  9. fotomoto

    fotomoto Active Member

    Do we have official confirmation on this? The C-Max, Prius plug-in, and the Prius Prime (all with much less EV range) have this mode too. In fact, we had one guy on the Cmax forum back in the day who was going to go back to the dealer to have his tank drained so it wouldn't engage the ICE, ever. On a car with only 19 miles EV available..... <cough, nutjob, cough>
  10. insightman

    insightman Well-Known Member

    We're talking about the HONDA Clarity Plug-In Hybrid, so "official confirmation" is a pretty rare thing. The only official confirmation would be if it was discussed in the Owners Guide, the Owners Manual, or one of the many papers published by Honda engineers. None of those sources has mentioned a feature that starts the ICE to use up old gasoline.
    ClarityDoc likes this.
  11. fotomoto

    fotomoto Active Member

    Well until we can confirm this otherwise, one has to work on the assumption it's a possibility. After all, here's what the maintenance minder does (bold mine):

    "The Maintenance Minder™ system monitors operating conditions such as oil and coolant temperature along with engine speed to determine the proper service intervals. Depending on operating conditions, oil change intervals can be extended to a maximum of 12,000 miles, potentially sparing the owner considerable expense and inconvenience over the life of the vehicle. The owner-resettable system monitors all normal service parts and systems, including oil and filter, tire rotation, air-cleaner, transmission fluid, spark plugs, coolant, brake pads and more."

    Monitoring fuel usage is just as easy to monitor as the above so it's certainly within the cars ability.
  12. KentuckyKen

    KentuckyKen Well-Known Member

    I have no official source doc from Honda on this. I just make the claim based on my experience over the past 14 months of ownership of 9,000+ miles.
    1. In 9 months without selecting HV or allowing SOC to deplete and auto engage HV, my Clarity’s computer has been happy to let my gas stay in the tank with no loss of bars on the gas gauge.
    2. Over a 12 month period, with one HV Trip and 3 gals used and replaced, again no loss of bars after putting in the 3 gal.

    Basically it’s only very occasionally running the ICE for very short periods with no significant gas consumption. There is no indication at all over the last year+ that it’s trying to run the ICE to keep the gas fresh like the Volt does.
    This is why @insightman kids me about shilling for the Stabil I’m using. (And RainX!)
    insightman likes this.
  13. fotomoto

    fotomoto Active Member

    Thanks for the data. You basically burned and replaced nearly 1/2 tank of fuel so could that possibly be enough to avoid FMM in your case? (if there is such a mode in the clarity) Have you heard of anyone here who's been 100% EV since purchase?

    I've never experienced FMM in either my CMax or previous Volt since I do numerous out of town trips; that's why I prefer PHEV's.
  14. KentuckyKen

    KentuckyKen Well-Known Member

    No I haven’t, but I did go 9 months in “EV” and it didn’t try to burn up the 3 gal of old gas in 12 months on its own. I guess you’re saying until someone goes a full year with no HV that we won’t know for 100% sure. But I’m going out on a limb and say no Volt like FMM in the Clarity until proven wrong.
    ClarityDoc and insightman like this.
  15. KClark

    KClark Active Member

    Did it again today, 65mph on a level freeway, ACC engaged, 70% SOC, no sudden acceleration. This is the 5th day in a row.
  16. ClarityBill

    ClarityBill Active Member

    Interesting experience (for those not having it, frustrating for those that do)...

    So, out of interest:
    How long after starting to drive did the ICE come on? and how long at 65 mph before coming on?
    Did the ICE rev, or just warm up rpm's?
    Did the ICE shut off on its own?
    Does the SOC keep decreasing like EV mode, or is it keeping charge like HV mode? HV charge mode?
    Do HV miles decrease (using gas)?
    Did it go to gear mode?
  17. KClark

    KClark Active Member

    My commute time on the freeway is about 25 minutes. It has been maybe 5-10 minutes after entering the freeway. No revving, no angry bees, not really objectionable at all and at first I wasn't sure if the ICE was on or not and so I started viewing the energy flow diagram on the display more often. I let the ICE run as long as it wants and that varies, I have several hills and sometimes it turns off for good once I start downhill, once it stayed on until I left the freeway and came to a complete stop. The charge stays relatively stable while it's on. I haven't seen the gear but I may have missed it. I have noticed power going to the wheels and charge going to the battery at various times according to the energy display.
  18. fotomoto

    fotomoto Active Member

    I spent some time searching but will readily admit my internet search skills are lacking and couldn't find any specific mention of it. But no denials either. So, the question remains.....

    I did find that Pacifica minivan plug-in has a 90 day limit. It would be very unusual that one of the longest range PHEV's, which is the most likely to avoid gas usage, doesn't have FMM. <shruggs>
  19. fotomoto

    fotomoto Active Member

    This might be your sign. Too much throttle at too high of speed (highway?), can be a trigger. Remember, there is no pure EV mode in the Clarity.

    Normal hybrid power flow behavior once the ICE is running.
  20. Tim66

    Tim66 Active Member Subscriber

    Exactly my issue. After the ICE engages (pedal past the detent) I've tried pushing the buttons to disengage or done nothing and it remains on. I've waited for several miles to go past the detent in EV mode and ICE engages but won't shut off, no buttons pushed (stayed on for an hour until I exited the freeway, got home and shut off the engine). I reported this issue and the stuck HV range to the dealer. They said both issues were fixed. But only the stuck HV range issue was corrected. I've engaged the ICE below 40 MPH and above and it always stays on no matter the SOC or length of operation. The service guy said it wasn't supposed to work that way. Back to the service department.

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