I have a 2018 Prime with around 60,000 miles. Probably 80% of my driving is EV mode, so the engine lives a pretty easy life. In the past few months I've noticed a few times where it idles for an extended amount of time. I'm not talking about the warm-up cycle, and it's been warm/hot here so it's not a cold weather thing. I use the Hybrid Assistant app to monitor it. Occasionally it's the Idle Check cycle, but at least once it wasn't. The engine will just stay on at 900-1000 RPM for a few minutes when it should otherwise be able to go into EV mode (warm enough, light or no throttle demand, etc). I guess it's not a big problem, but does it indicate some kind of issue I should be looking for? I've also had a few rougher than normal engine starts, if that means anything.
the same thing was happening on my 2012. i suspect it is because the engine runs so infrequently and often for very short periods of time. an italian tune up cured it, and it might have been the egr, idk. gen 4 egr is different, so i'm not sure if it is the same problem.
Primes are pretty sophisticated. Second guessing what the Prime does with EV while in HV mode is near impossible. especially if driver is looking closely at how efficiently the systems handle switch overs that you / we / us think could have should have bin done differently. Sure, if you really want to get a feel for how the car actually handles EVERYTHING it (the car) gets exposed to over its lifetime, (don't forget history data here), monitoring at slower than normal speed with no traffic or other driver distractions, provides insights most drivers never ever never see. Once those stats get confirmed by both trial and error as well as getting reproduced enough times for a driver to be comfortable adding them to the base stats, its way easier to adjust them to normal and rush hours type situations. I'm always second guessing the Primes behavior, especially when the car is doing something I think could be done more efficiently to meet() (my personal needs). That's my (problem), not the Primes !
This may not apply here, but when in Hybrid mode, the ICE will run occasionally to bring the charge in the traction battery up to a desired level. This is distinct from the warm-up cycle.
When it's charging that battery it's not idling (900-1000 RPM). It's usually higher, but I can't remember what RPM it prefers for charging while stopped. Or maybe it's not much higher, but it's at least under load. It sounds distinctly different when it's charging the battery. In charge mode it will occasionally idle when it can't charge (maybe when coming to a stop), but then it will start charging again when it can, after being stopped for a couple seconds or after starting to drive.
^ This. The RPM is about the same, but when idling it's, well, idle, as opposed to charging when the throttle has to open wider 'cause it's doing actual work. You can hear the deeper exhaust note. At least that's how the older generations do it; I haven't listened to a Prime.
