My Clarity really annoyed me yesterday!

I have the same year and model and have not experienced that. I’ve heard just turning the car off and back on may resolve issues such as you describe. Though it clearly should not be necessary, did you try that? If it continues to be an issue, maybe disconnect and reconnect the 12v battery to reset everything.

Good luck. Sounds VERY annoying.

 

Obviously loud is subjective, but as a CT resident and someone who often drives behind the EV range, I do notice more engine noise when cold (even when having EV range left). It's never bothered me, but noticeable. I believe it's tied to HVAC usage - ie the car believes it is more efficient to use the engine to heat. I keep the temps pretty low when I'm driving solo but passengers usually don't tolerate that lol.

Wish this car would have had a heat pump but no such luck.

 

Living in the south, I haven't driven a lot with temps below freezing. I do believe that the heater load is a lot when working hard to heat the car. I think I have read that it can draw as much as 6-7 KW, but I'm not sure about that. If it is that much, it doesn't surprise me that the engine would have to rev a little with both the heating load and propulsion load. Probably nothing wrong with your car, but I hate for you that it was annoying.

 

Approximately how fast were you going while this was happening? I too am thinking that it was a perfect storm of propulsion demand, heater load, and possibly the "hilliness". It will be interesting to see if this just resolves when you return to your normal routine. I think the chances are good that everything is fine, but I agree that this can be disconcerting.

 

Unless we were sitting in your car when it happened and heard it for ourselves, it's very hard to tell from these type of reports if it's just normal behavior that is simply misunderstood by a newer owner, or if there was really something out of the ordinary going on. But based on the fact that you seem to have quite a lot of experience with your car (three years plus?) and that you are already used to the higher rev sounds that the car can make at times, including on the same route and in similar temperatures, your description of extremely high RPM's that lasted for over an hour on relatively normal terrain and with plenty of battery charge, sounds to me like the problem that a small percentage of Clarity owners have experienced. In virtually all of these cases that I have heard of the high RPM's can only be stopped by switching to EV or by turning the car off and on. Some people have also reported a massive power along with the high RPM's, although there is a theory that they were actually backing off the throttle unconsciously when it happened because of the loud noise. In fact that seemed to be your reaction as well, although in your case you were conscious of doing it.

It's a problem that seems to be nearly impossible to reproduce, at least not on cue, and there never seem to be error codes, so taking it to a dealer typically goes nowhere. However there is some indication that doing a 12V reset as Fast Eddie B mentioned will help prevent it from happening again. Unfortunately most of the people who report the problem on forums like this or on the NHTSA website tend to come and go and we never hear if or how the problem was resolved. But doing a 12V reset is easy and safe to do, all you have to do is disconnect the negative terminal from the battery, then after a minute or so reconnect it. You will know that you have successfully done a reset because the next time you start the car you will be presented with several error messages about failed systems on your car, but those go away quickly once you start driving.

 

Well of course I meant to say a massive loss of power. But I'm guessing everyone probably figured that out anyway because no Clarity owner would ever be reporting a massive amount of power! Not that it isn't adequate, but not exactly massive.

 

I have felt that way many times... That was when I started doing the 'HV reset': Just switch to EV mode for 2 seconds by pushing the HV button twice, slowly. This puts the drive back to engine drive mode, and reduces the engine RPM. You need to have some battery capacity available to do this.

For me, the noise is higher when the ignition timing gets a little out of whack. For the first 70K miles of my driving, it was consistently noisy at high engine RPM. I used some 90 octane fuel, this seemed to jump the timing, and the noise has been much better even when I use 87 octane. I still get an occasional drive with high noise. Last time it happened, the timing was over 30. (It normally runs 8-20)

 

This is the first time someone has described a way to force the Clarity PHEV into Engine Drive Mode.

In my experience, you have to coddle the car at speeds greater than 45 mph to achieve Engine Drive Mode--then any significant pressure on the accelerator takes it out of Engine Drive Mode.

But you are able to take your Clarity out of HV for 2 seconds, then re-engage HV and your Clarity will immediately switch on Engine Drive Mode? Is Engine Drive Mode engaged this way any more willing to accept hill-duty?

 

I think @ClarityBill may have mis-spoke?...
I think all he is describing is a way to reset the HV 'setpoint', and NOT engaging 'engine drive' mode.

 

I think it may be likely that once the engine can rely more on the battery (after resetting the battery level 'setpoint'), the power output required (RPM) from the engine lessens and the car can go back into Engine drive mode (gear illuminated on center screen). It's an interesting idea. I'll certainly be more likely in cold weather and hilly drives to hold all of my battery at the start of the drive (I usually hold a little more than half) so that this technique can be used if RPM seems to be getting out of hand. It might also be a good use of the battery to improve overall efficiency.

 

I know that I have discussed this previously... Maybe you were not involved in the conversation.

That was 7/20/20

It is resetting the HV mode set point, but when you are over 45 mph, the car will go into engine drive mode. I would say that it goes to engine drive mode 100% of the time. (When starting with RPM over synchronous speed.)

Most of my driving is at 78 mph on interstates, so I have a lot of experience with hills and high rpm's.

 

I've experienced where the HV mode sets the battery charge that it attempts to maintain while driving - say 20 estimated EV miles. As I drive, especially in hills, cold, with few stops that help regen, the HV fails to keep up. At a certain point, say 3 or 4 EV miles under the set point, the engine starts to rev in an apparent attempt to bring the charge back up. For me, I think the underpower feeling is the disconnect between the RPM noise level and the speed response of the car. The engine runs faster, but the car doesn't go faster, so it feels underpowered. I've never had any problem maintaining speed, however.

Your trip back with more back roads would give your car more opportunities to regen. HV seems to struggle to maintain the charge set point with a lot of accelerating from stops or up to higher speed limits. We did a trip with back roads when it was 0 to -5F. We lost more charge to accelerating than we gained from regen. Our stops weren't long enough to build up charge with it that cold.

 

If you get a chance to test this again, and experience similar, and assuming EV (battery) not = 0, I'd intentionally push the accelerator hard like you don't care if you ruin your car. My car has in many cases made huge and uncomfortable sounds (that have caused passengers to ask if my car is OK), but it has never lost power. When it rev's high, temptation is to decelerate but that won't tell you if you have what can be normal sounds, or a more serious problem.

If the car ever loses power while you're pressing the gas hard, that's a more serious problem. That abnormality is very rare, but I have seen it reported. Of course if that occurs its a safety issue. Hopefully your Clarity isn't in that situation.

So the gist of my note is that there's some value in determining if your human response to the high rev sound is to decelerate (oh my god, I'm killing the car kind of thing), or if you really are losing power. Both are possible. The human response is understandable, but easily surmountable. When my Clarity does "angry bees," sound I turn up the stereo and move on, but I've never lost power.

-Dan

Oh and Clarity Bill mentioned an important trick. To change the set point when high reving, just go to EV only for a couple seconds, then re-engage HV. i.e. tap HV to turn off HV, then turn it back on.

 

@ClarityBill's trick also included getting the Clarity to activate Engine Drive Mode, which will definitely lower the RPMs as that mode links the car's engine speed to the road speed.

 

Why would there be an electric heating load when the gas engine is running? Unless some impossible temperature was selected such as 80 when its way below zero out.

 

You are probably right. With the gas engine running, there probably aren't many conditions which would run the electric heating load once the engine warms up. Hadn't thought that through well...

 

There seems to be a growing suspicion that the electric heater is used even when the engine is running. Apparently it only uses engine heat in extremely cold conditions when the resistance heater can't keep up by itself. As nonsensical as that sounds, one theory is that they felt they could control the temperature better with the resistance heater than with engine heat. Would be nice if somehow the OBD scanner was able to report the usage of the resistance heater and how much power it is drawing at any time.

 

Can anyone demonstrate that the Clarity will remain in EDM outside of the range of operation shown above, regardless of the method used to engaged EDM?