S4 (Stage 4) Temperature

[efusco]

Originally Posted by tom1l21

My engine temp was at 172F when I came upon a red light. After waiting for 20 seconds, I accelerated off and tried gliding which didn't work. I then came to another red light at 180F 15s down the road and again waited for 30s. After accelerating, I was able to glide. How come I wasn't able to at the first red light?

Was the ICE running when you waited the first time? Probably not. If you come to a stop and are not sure if the ICE is running, just gun the accellerator (with your foot firmly on the brake) to get it running, then wait until you feel it idle off.

[hobbit]

Those little cooldowns are a good reason to install an ECT fakeout.
Even a little boost can get you back over a 70C reading as you
take off again and can get right back into the glides.
.
_H*

[ken1784]

Originally Posted by efusco

If you come to a stop and are not sure if the ICE is running, just gun the accellerator (with your foot firmly on the brake) to get it running, then wait until you feel it idle off.

Adding to Dr. Evan's comment...

Shift to P, then gun the accelerator.
Or,
Power off, then restart Prius after five seconds or more.

Ken@Japan

[tom1l21]

Originally Posted by efusco

Was the ICE running when you waited the first time? Probably not. If you come to a stop and are not sure if the ICE is running, just gun the accellerator (with your foot firmly on the brake) to get it running, then wait until you feel it idle off.

No, the ICE was not running while I waited at the first light. It ran as I approached the light, and once I stopped, it shut off. Since it was in the 170's, I thought when it shut off it would constitute as one of those "idle checks" you were talking about previously. I guess it shut down the ICE but it didn't do the "idle check."? Wonder why. Sorry if I am not understanding this.

BTW, I can tell when the ICE is running either by the sound of it or the RPM's on my scangauge.

[Bob64]

How fast were you going as you approached the first light? Over 35mph?

Heres what I think may have happened:

You were traveling between 35-40mph. You started to deaccelerate. Because you were in stage 3, the engine shutoff as you approached the stoplight (conditions for engine stop: between 35-40mph, coolant temp above 70c, stage3 or above). As you accelerated to the second stoplight, you did not reach 35mph, so the engine was running as you stopped at the second stoplight. Because the engine was idling for over 7 seconds at 2nd stoplight, you entered stage 4, and the engine stopped. After the second stoplight, you are able to glide at any speed under 41mph.

[tom1l21]

How fast were you going as you approached the first light? Over 35mph?

I believe so, the speed limit there is 40mph.

Heres what I think may have happened:

You were traveling between 35-40mph. You started to deaccelerate. Because you were in stage 3, the engine shutoff as you approached the stoplight (conditions for engine stop: between 35-40mph, coolant temp above 70c, stage3 or above). As you accelerated to the second stoplight, you did not reach 35mph, so the engine was running as you stopped at the second stoplight. Because the engine was idling for over 7 seconds at 2nd stoplight, you entered stage 4, and the engine stopped. After the second stoplight, you are able to glide at any speed under 41mph.

That seems right, I didn't reach 35 going to the 2nd light. Good insight, I think I might have it figured out now. Thanks!

EDIT: One other question. What would cause the engine to run if the temperature is ~180 and the battery is at 6 bars when trying to glide. No heat or air conditioner on. This seems to happen sometimes out of the blue, my guess is that it is the battery, even at 6 bars, will still charge if it drops below a certain SOC?

[TheForce]

If you just reach around 176F-180F the engine must run to curculate the coolent or something. I cant really remember right now. It takes about 30 or so to do this then you can get back into a glide.

[Bob64]

I've noticed this behavior before and I believe someone mentioned that it was storing hot coolant in the thermos when that happens. Tends to happen early on in the commute, after which the computers is like: oh, the thermos stored as much heat as it can, lets not bother with this anymore.

[tom1l21]

Thanks for clearing up the previous point. Makes sense.

Sometimes I can stop at a light for several seconds at 150 F and when I accelerate off, I can then glide even under 159F. Is this stage 3b or something? It never did the idle check until I came to another stop after that was at 170F. I could definitely feel the idle check shudder there.

[ken1784]

Under 159F, you were in stage-2.

Ken@Japan