"warming up" the engine

You can add a block heater if there's a need in your neck of the woods. That should keep it warm so it take less time to get up to temperature.

 

Or add the engine block heater like some of the guys here. Do a search on block heater or something to read more about it.

Like Tony said, if you idle, you are getting ZERO MPG!

 

i'd sooner get 25 mpg for a bit than 0 mpg for a bit

just drive it and you'll be set. by losing the guzzler you're already leaps and bounds ahead of the game

 

ITA with what the other responders have said. It doesn't do any good to let the Prius just sit still while the engine warms up, while it can warm up just as well (if not better) while moving.

 

To add to this, how is the car in the colder parts of the country. That is how long does it take to warm up when its 15 degrees outside?

 

If you have an EV switch, following is the best warming up strategy discussed among Japanese mileage enthusiasts.

- Push START, then ICE will start in several seconds.
- Watch your energy screen, you'll see some battery charging.
- After exact 56 seconds, the charging will stop and you'll hear the engine noize is changed.
- Push EV switch, then the ICE stops.
- Start your vehicle.
- Off the EV switch when you are accelerating (accelerate using ICE) and on the EV switch when you are slowing down (coast without ICE power).
- Repeat it until you are at Stage-2.
- Be carefull about the idling check in Stage-3.

Please refer to...
http://priuschat.com/forums/kb.php?mode=article&k=14

Ken@Japan

 

The Prius warms up just fine in the cold (Maine).

When it's shut down the car pumps the hot coolant into a thermos bottle to keep it warm. When the car starts up it, pumps the hot/warm coolant back into the cold engine to preheat it. It works fine.

FWIW, plenty of heat in the cabin. The engineers did their job well. For such a small 4 banger, it's the best at heating the cabin of any small 4 we've ever owned.

 

For the first 30 [or maybe it's 56] seconds, the car mostly pushes
you with the electric motors and tries to avoid loading the engine
at all. This is good -- it's generally bad to put a hard load on
a cold engine. If you request a *lot* of power right after starting
then it will load the engine to give you that, but you should never
have a reason to do that. So by starting up and promptly but gently
moving, you're creating the conditions it was designed to do best.
.
You can't "idle for 10 minutes", either, unless you put it in
neutral. If you're sitting there in Park, once the engine hits
40 deg C it shuts down until you wanna go. That's not very hot, so
it doesn't take long.
.
_H*

 

<div class='quotetop'>QUOTE(ken1784 @ May 3 2006, 04:28 PM) [snapback]249246[/snapback]</div>

I read the "5 Stages" article, but there's no mention of the "idling check" in Stage-3. Why do we have to be careful about it? Thanks!

 

<div class='quotetop'>QUOTE(XGasGuzzler @ May 3 2006, 12:15 PM) [snapback]249199[/snapback]</div>

To get back to your original concern:

As you may not know if you haven't run across it on one thread or another, the Prius is engineered to warm up the catalytic converter to its optimum temperature FIRST---in order to minimize emissions. During this time (roughly the first few/5 minutes, depending on the temp the engine already is) it's hard to get much above 25-30 MPG.

Once the cat is warm, you'll start getting "normal" MPG. And, as you'll note on the MFD, you may still see increasing plateaus of MPG for the next 2-3 5-minute increments.

That's what was meant. But as far as warming it up and "not having it count against you", forget it. That initial cat warm-up drags all of our MPGs down---and the shorter your trip, the more it'll hurt.

 

When the Prius gas engine cold-starts, it runs slightly rich and with retarded engine timing. It is then little more than a "hot gas generator", throwing unburned hydrocarbons and oxygen at the catalytic converter. CC very quickly gets hot enough to do its job; 350 - 400 oC.

If you ask for much power during this time, the ICE (I find) makes ugly sounds, but provides the requested power anyway. Hence, some will recommend that you limit your power demands during warmup. It may be abusive.

IMO the only reason to perform a stationary warmup is to clear ice and snow from the windows. This is a very good reason! Please don't anybody drive off until all the windows are cleared. Use your scraper.

If the HV battery is too cold to provide or accept much charge during this time, it won't. But all that is out of our hands. Just drive, as soon as the windows are cleared. It's gonna be OK.

 

<div class='quotetop'>QUOTE(XGasGuzzler @ May 3 2006, 12:15 PM) [snapback]249199[/snapback]</div>

Do not warm up your Prius, in fact it is totally unnecessary to warm up any cars newer than 1980! (I thought most car sales people tell their customers explicitly not to warm up - just start and drive off.) It's a waste of gas and pollutes unnecessarily. Running an engine at idle is also bad for the catalytic converters - shortens their lives. There use be an old-wife tale about having to let the oil circulate - that's a bogus claim - the oil should be circulating in your engine within a second of cranking - and if it does'nt circulate properly, it doesn't matter whether you are moving the car or not. Even if you leave your car parked for days or weeks in a very cold weather, there is still a film of oil between the bearings to keep it lubricated for the first few turns of the crank - warming up without moving the car does nothing different so why stay at idle to warm it up?

In the old days of carbarretted engines, it was necessary becuase the fuel/air mixture depended on the size of the orifice and spring tension of the floats etc of the carb and when it's cold, the mixture is way mal-adjusted and the engine runs rough and cannot sustain the load - causing the engine to stall if you just drive off. All modern cars use computer controls and do not have that problem.

What is true is that a warm engine have lower emission than when it's cold. For the prius, when you turn off the car, you can hear a little gurgling sound in the engine. It's a little electric pump filling up a thermos flask located in front (near the head lights) with hot coolant to store. So, the next morning, as soon as you start the car, the hot coolant stored in that thermos flask is ciculated in your engine - warming it up right away to get the lowest possible emission. .. see they think of everything.

 

Redwood City CA. You might very well benefit in the MPG category with a block heater and a timer! I cut my time to Stage 4 operation to a few blocks this time of year with 2 hr of pre heating. I am then in the optimal temperature range. It does not take long to heat up the catalytic converter. (One wonders if that is on the CAN Bus, but that is another discussion). It heats up fast. Get the coolant temp up and you are in the "zone". I sometimes wonder that those of us in the mild climates where it does not get too warm or too cold may get more bang from a block heater than those in more extreme climates. What do people think?

 

<div class='quotetop'>QUOTE(plasm @ May 4 2006, 11:55 AM) [snapback]249486[/snapback]</div>

The article says "In S3a the ICE will not shut off unless you come to a full stop for 5 or 10 seconds."
The idling check is done at a full stop for 5 or 10 seconds.
The ICE won't stop even on coasting. This means you are wasting your fuel.

Ken@Japan

 

You can determine the cat state by looking at the O2 sensor readings.. The first sensor will tell you when the engine is running in closed loop and the second tells you if the cat is up to temperature and working.

What I've been experimenting with recently is spoofing the coolant temperature sensor to get my Classic Prius into its equivalent of "stage 4" as quickly as possible (the Classic behaves similarly to the HSD Prius, but the transition temperatures are a bit different and it doesn't have a Stage 2- the car absolutely will not go into auto-stop until the coolant temperature reaches 70C). Because of the differences in the start-up algorithm and the fact that the Classic does not have the thermos, the Classic's first 5-minute consumption is much worse.

By spoofing the coolant temp sensor and rapidly ramping up the apparent temperature to 70C, I see improvements in the first 5-minute consumption by 20% or more.. If nothing else, a spoofed ramp to 50C makes the cold temp light on the dash go out and stops the retarded timing mode so that the engine can start producing power. Looking at the differences in actual engine temperature, the Classic Prius "warm up" sequence does get the engine to temperature slightly faster (about 500m-1km of additional driving distance faster from a cold engine (sitting overnight)), but it also burns at least 20% more fuel to do this.. I haven't done the math, but it seems that the difference in emissions is probably on the side of the spoofed warm up vs. the default sequence- needing to going an extra km to reach temp while burning 20% less gas would seem to be the right choice vs. burning more gas simply to get extra heat.. I would think that as long as I'm not idling, but driving away immediately after start, that my emissions would be far better despite bypassing the warm-up sequence..