ICE didn't stop running

Hi Guys,

The other day while driving home from work (about 10-mile drive one way). I am more than half-way through and waiting on a traffic light. I realized the engine (ICE) didn't stop running. Battery was showing about 5-6 bars and the engine was warm. Outside temps were in mid 70s. That's what you get in December in FL.
I remember something similar in the past and ignored it. A few miles later, I am on another stop. The engine is still running. The Energy monitor is showing no Green or Red arrows. That's the status you get when the ICE is not running, and the car is at a complete stop. I pressed the brake pedal a bit harder to see if that would help. It didn't.
Traffic started moving and once I was close to my home in neighborhood roads (25-mhp zone), I pulled over and shut off the car. Yes, the engine was still running (probably never stopped running for the past 10-15 minutes). I waited for a minute and turned it back on. The engine stayed off. And the battery level indicator jumped to 8 bars. This would normally never happen in Florida roads. I was about 3/4 of a mile away from home and I got to my home on all electric. When I got home, I still had 7 bars on the battery.

The car overcharged the hybrid battery by refusing to stop the engine.

This never happened to me before. Any idea what might have caused it?

 

Thanks for the ideas. The car has 194k miles on it. I bought it in 2017 at 142k miles. And in 2018, I cleaned the EGR circuit. The EGR cooler was very bad but not entirely clogged after 7 years and 142k miles. I cleaned it so meticulously. I can't imagine it is getting clogged again. Would EGR circuit cause this type of behavior? I doubt. Throttle body? I removed and cleaned it the same time I cleaned the EGR system. Not sure what I can check on it with no code in the system.
I wanted to focus on my deteriorating hybrid pack, but the pack is holding charge. It is getting weaker I can feel it, but it is still doing its job.

I cannot think of what might be causing this other than the computer system. ECM decides when to shut down the ICE. And when the conditions met, it sends the signal (probably cutting the ignition or stopping the injectors). The ICE cannot keep running if either the fuel flow or the ignition is cut. Clearly the vehicle's engine management system didn't shut off the ICE or it didn't see all the conditions were met to shut off the ICE. Really interesting.

I drove the car yesterday for 40 miles and it worked just fine.

 

Hi guys,

I have been away for a few days; just catching up with the replies. For those who suggest that my engine kept running to deplete the excess charge, this is not the case here. I experience that once in Atlanta after going downhill for a while and hitting 8 bars the engine refused to shut off.
I wasn't at 8 bars when it happened here last week. It hit 8 bars after I recycled the power.

The idea (by ASRDogman) of it kept running to charge one of the weak blocks (out of the 14) could be possible. I have a Dr. Prius app. I used it in the past to monitor the battery blocks, but I didn't find it useful. The block voltages were fluctuating every second. You don't understand anything unless maybe you record the screen and watch it later. The other issue with it is the OBD II dongle. If you leave that thing there too long, it will interfere with the braking system and cause the yellow brake and exclamation mark to illuminate on the dash. This happened to me. I removed the dongle and never had the issue again in 3 years passed. This may not happen with every type/brand dongle but some of them causing it. There are reports of it on the forums.

After week of driving regularly, I didn't experience the issue again. But if it is a battery related, it will eventually happen again. And if it is a weak block, I can replace a pack or two and could possibly fix it. I have removed and replaced packs on friends Prius a few times. The last time I checked my hybrid packs was about two years ago. They were all about the same level. I didn't replace anything other than shuffling them.
So, I still have the original hybrid battery packs at 195k miles. I know they aren't gonna last forever.

 

I like the strategy ASR. That's what I am doing as well. Don't want to replace my car till the price goes back down to normal levels.
What is the Prolong system?

 

Thanks for the link.

It looks good but kind of overpriced to me with around $400. I think one can DIY this thing for around $100 (if he had the knowledge of course.)
I saw the other thread started by CatNinja. He came up with his own charging set up. Good info but there is no step-by-step instructions on how to build it.