multiple shut-downs

I don't know what you mean? Does the car stop for no reason when you are driving it?

 

If you mean that the ICE cycles more often, you can attribute that to cold weather.

 

Normal. The colder the weather the more the engine has to run to keep itself (and you) warm.

 

I still don't understand what you're trying to say

Your posts are still confusing.

Assuming sufficient charge and that it doesn't have to run the ICE to keep the heat going, it SHOULD shut down when you come to a stop. Also, it might shut down (w/o you knowing it) when you're below 42 mph.

What's wrong w/the shut downs? There's no reason to run the ICE when it doesn't need to run.

 

The engine will turn off when ever it can. If you need it to power the car it will come on and if it gets cold it will run. It will turn off every time you lift your foot off the accelerator once warm. It will restart if you accelerate.

 

Answer:

Either you are not in stage 4 OR your engine coolant temp has dropped below 70c.

If your not in stage 4, the engine won't "shutdown" unless it reaches a speed of 35mph-40mph and a coolant temp of over 70c.

If your coolant temp is over 70c and your not in stage 4, it will only transition to stage 4 if your at a very slow speed - like 1-2mph with your foot OFF the gas (or a complete stop, for about 7 seconds).

Once your in stage 4, it will usually bring you back to stage 4 (if you drop below 70c and thus enter stage 3a) once your coolant temps reaches 70c or above.



Clear as mud?


Workaround: Blocking your grill to decrease warmup time as well as heat retention, thus decreasing the chances of the coolant temp dropping below 70c.

 

Yes. The engine wants to be around 180'F, so even 50'F ambient seems cold to it. Stop worrying about this.

 

The simple translation is, every time your ICE shuts down it starts cooling off. In the winter, it cools off faster. Consequently it has to run more often to warm itself back up. This is why a lot of people start blocking their grills below 50 (some even below 70). The reduced airflow over the engine helps it retain heat, reduces engine cycling, and improves mileage (and probably emissions).

Rob

 

I'm not sure if this is the same situation I've been experiencing in my 2008 Prius:

The temperatures here in So. Cal have been relatively mild (low to mid 50's in the mornings) compared to other parts of the country. In the mornings on my way to work, I usually have to stop at a traffic signal about two minutes from my house. The gas engine in my Prius will cycle on and off repeatedly while I'm waiting at the traffic light. Depending on the duration of the red light and how long I have to wait (usually no more than 20 seconds), the engine will cycle on and off up to 5 times. This is accompanied by a "shudder" each time the engine does this. However, once I've driven the car a few more minutes, this situation goes away. Is this due to the car needing more time to warm up? I'm wondering if other Prius owners have experienced this and is it normal.

 

Certainly normal. I wondered about this too during SoCal "winter" because I had a similar situation. When I moved up to the frozen tundra (not really, but it's all relative), the engine definitely runs more. Try turning off the climate control until after you take off from that first light, and you'll have far fewer restarts. Cheaper and easier than installing an engine block heater.

 

Is your heater (temperature above LO) on at all or are you using the auto climate control? If yes, that could cause the ICE to come on and/or stay running.

I've sat at traffic lights soon after leaving work w/the ICE running. Right when I press the Off fan "button", the ICE shuts down.

Also, if the HV battery is low, the ICE will come on to charge it.

 

Normally, I just have the vent running on a lower fan speed. I don't need to use A/C or heat.

 

The climate control is a bit more complicated, and you may be drawing heat anyway, even if it's not on "A/C auto". On the climate screen, if your cabin temp is lower than your target, the car will open the heat exchanger and pull heat from the coolant, making the ICE run more. At the same time, even if the A/C light is activated, it won't turn on the compressor unless the target temp tells it to cool the cabin by being lower than the cabin temp. or it is needed to dehumidify the cabin.

Try turning the fan all the way to off or push the "A/C Auto" button on your wheel until your MFD says "Air Conditioning Off." If you do this, the ICE won't turn on at stops unless your coolant is under ~104(?).