Drop out of S4 for no apparent reason?

i think my car does the same thing, and it's particularly notieable when i go to work. i do 4 miles on back roads, 2 miles on the highway and then hit the back of a shopping plaza. it's a windy slow (10-15mph) flat access road that i should be able to do in all electric. but many times, even tho the battery is full green, just a slight touch of the accellerator turns the engine on.

 

I'll be watching this thread, hoping to learn, as I have noticed the same thing. I've told myself there are probably more variables than we are aware of that go into those software decisions.

 

Could be as simple as low coolant temp. If it drops back below 70C the car will run according to Stage 2 rules until it warms back up.

 

right, but unlikely on a 70 degree day after 15 minutes of driving?

 

OK, what is "S4".

 

This is a pain in the nice person when it happens. The engine will run when coolant is being transferred to the thermos, but the odd thing I don't understand is that when this happens (if that's the cause, even, I don't actually know...), it happens throughout an entire ride, not just once.

The times it's happened there's been a huge range of SOC, sometimes low, sometimes high. Coolant always plenty warm, but no one specific temperature. In other words, I don't see any "cause" from the numbers.

The other day I was so annoyed that I pulled over and turned off the car. Upon restart it was fine, that's the only way I've found to get around it. I can't remember if I had to get back into stage 4 again or if it was already there somehow when I did this.

 

http://priuschat.com/forums/knowled...12919-five-stages-prius-hybrid-operation.html
http://priuschat.com/forums/knowled...perating-mode-availability-reference-aid.html

 

Wanted to update on something.

It happened to me tonight, so after grumbling down the backside of a bridge with the engine running, I pulled over, turned off the car, and started it right up again. I didn't wait even a couple seconds, cause I wanted to make sure ScanGauge kept thinking it was the "current" trip. I started up again, and the problem was gone. Even better, it was in stage 4 right away! This was in a 2007 Prius.

 

interesting. what do you think happened? glitch?

 

P.S. Forgot I took this pic, too. You can see after I turned it back on the first five minutes were in stage 4.

 

It seems to be, doesn't it? I have no technical expertise to comment on it, but at least we know a somewhat easy way to fix it if the car is stopped.

 

Very interesting data, 2009. I've read before that the coolant can take a minute or so to do its thing. On some of those it looks like a full 100 seconds, so a minute and forty seconds(!!) that the engine wouldn't turn off.

 

whattayou got there, francais?

 

nice! wish bob wilson was still around.

 

Yuppers, exactly. Stopped completely, with foot on brake turned off car. Without removing foot from brake started it up probably within one second or so. Started driving and the car was in S4 right away. I pulsed up to 20 mph, let off the pedal, and I was gliding at 0 RPM. No more S4 dance for the remainder of the half hour trip, and no idle ceremony to get into it, was just there.

 

My 08 seems to work fine. I will attempt to log RPM today to confirm.

Is there an EVAP canister that is being purged?

What is the HV bat Temp?