Gen3 warming up stages

Yes, where safe to do so.

Without a scangauge or similar tool to observe engine coolant temp, you are left guessing. Try at the end of the segments you describe. If the ICE does not re-enter S1a, then you've made it. That is, if the ICE stays off while stopped once you restart.

Those are pretty short distances mentioned to go from 50F to 140F, but it may get close. If it works, try it sooner.

But the big deal with this is when starting on a mostly warm but not quite warm engine, where you can end S1a early. That will not be the case cold. Assuming you have normal driving past the segments described, it will not be a huge deal because you will get from 140F to 157F rather quickly and get S4 with a coast below 45 mph.

Not wrong, but you only want to draw what S1a (and S1b excess power during your initial driving) will replace the next morning. All other regen is less than optimal for fuel economy. After that, put ICE to wheels and get a move on.

 

Thank you ksstathead. I'll try experimenting with the shut off.

 

Some observations from this morning:

ICE temp at S0 35 degrees F (1.7C) (ambient temp)
ICE temp when entering S1b 55 degrees (12.7C)
With heating system off in ECO mode, I was able to achieve a power off glide (RPM to 0) from 35 MPH with ICE temp at 107 degrees (41.6C). I'll try at a lower temperature tomorrow.

Nothing new here, I think this confirms previous observations by others.

 

Would someone with GenII AND GenIII experience please answer me a question:
Everyone says 'FEW' seconds when talking about getting from S3 to S4. Is there a difference in "FEW" between GenII and GenIII?

I find the 'idling check ceremony' in the GenII sooo annoying. Especially to be forced to a full stop in the GenII bothers me. Sometimes it takes over 10 seconds in a full stop to get over that crappy S3.
On my test drive with the GenIII I was under the impression that it only takes 2-3 seconds of deceleration to get from S3 to S4 in the new one. Is that right?

What sence does this 'ceremony' make at all?

thx
W.

 

Has anyone tried to modify the CPU to change the overall programming for all this pollution control code?
I would be interested in trading a small amount of clean/green for not having the engine automatically come on when the engine is still fairly warm. Just taper back the aggressive programming?
I ask because I have used CPU modification for performance cars, so it should be possible to do this for the Prius.

 

I would like to rank this thread as "very useful".
Had some posts quoted in Prius-Pt, hope the authors rightfully be "payed off" with this public appreciation.
Many thanks!

 

Hello all,

Ok, once again, very new here.. this post confused the heck outa me..

1. In the warmer temps, am I supposed to "warm up" my prius?
1a, In the winter, do I need to warm my car up?

Sorry guys and gals.. just trying to comprehend.

 

Frazz, I'll try to give you some basic information to fill in the blanks, you may already know this:

When the car is cold the ICE will start about 12 seconds after you push the power button with the brake depressed and enter the Ready mode. You can start it sooner simply by pushing the throttle to the floor and then releasing it, I usually do this.

Once the ICE is running (stage s1a) it will continue to run for about 50 seconds, during this time the ICE will supply no power to charge the battery or to drive the wheels. If you had to have power and pushed your foot way down it would provide some but it doesn't like to do so unless it has to. This time is used to warm up the ICE and the catalytic converter to help keep emissions to a minimum. Emissions come first and fuel mileage second.

So when you drive off during stage s1a you will be running on the battery. That means the power that comes out of the battery must eventually be put back in by the ICE and that results in a net loss due to conversion. One of our more knowledgeable posters (Ken1784) mentioned sometime ago that we would be better off just to sit in the driveway for the 50 seconds of stage s1a.

Remember all the power the car uses ultimately comes from the gas in the tank. If you charge the battery by going down hill or using regenerative braking the ICE had to use gas to get you up the hill or up to speed, etc.

There are better and more detailed explanations on here but that may help to start out with.

What we have here would indicate that if the ICE coolant temp is below 104 degrees F. the car will enter stage s1a. I am not sure that always happens so I will watch mine and try to find out. I believe it is a good idea to wait out the 50 seconds (or until the temperature reaches 149 degrees).

 

My understanding is that it's 10 seconds on both.

I've never experienced it taking longer than 10 seconds. A second is longer than most people think it is. Further, the engine management computer must be in idle mode - you cannot press the power pedal at all in the 10 second period.

The Gen 2 requires that the car is practically stopped - creeping - before it will drop into idle. However, it won't stop the engine below 38mph (indicated, on my car, so around 35mph actual) if it's already running, once in S3.

It sounds like the full 10 seconds idling is still required, but it no longer requires the car to be practically stopped to drop into idle, just no demand for the engine.

My understanding is that it's calibrating the Mass Air Flow sensor, to decide if it can trust the values that it's sending. The MAF is used to calculate how much fuel to inject in closed-loop fuel control (which is Stage 4). If it can't trust the MAF it flags a DTC instead of going into Stage 4.

There's really no need to do anything special. You can't get the best fuel economy and lowest emissions without waiting for the warmup process to finish, but on Gen 3 this should normally be possible just in regular driving. On the Gen 2 the engine would mysteriously stay on at times when there was plenty of battery power, if you hadn't slowed to under 7mph for ten seconds (and not accelerated during that time).

Waiting for about a minute for the car to warm up to stage 2 or 3 reduces stress on the traction battery a little bit. It may be a good idea if you need to accelerate hard shortly after switching on. On my commute home, immediately after switching on I pull out onto a 40mph road and less than half a mile later, the speed limit increases to 50mph. Traffic expects you to be doing these speeds. It's common to see the battery drain to three or even two bars because the car prefers running on battery until the engine warms up to 40°C or so.

The Gen 2 car will also run the engine at this stage if you do need to accelerate hard; it's a bit disconcerting for it to go from idle to suddenly racing as it decides to try to accelerate with very late timing (and very little power).

 

I've done extensive modification to the ECU programming in my GM diesel truck with EFILive....not copying in someone else's stuff...doing my own.

I've also researched Toyota ECU programming. From what I can tell, Toyota doesn't use tables, they use formulas in the programming. The tuning is also very buried in the computer and noone has done much reverse engineering for Toyota ECU's.

I wish they had though...I'm with you.

If anyone finds a software package to retune (no not Techstream, that's for maintenance) Toyotas (like EFILive does for GM) please post it up here.

 

is this car drinking gas or just normal?

 

I have 20 then 30 then 40 mph posted speed limits on my commute, so I like to move during s1a, because I can cover a lot of ground gliding which is way better than sitting still. Would be different if I were getting on freeway cold. So, it all depends. When I drive during s1a, I just try to be gentle on the accelerator.

 

I think there is Stage 5. Talking from gen2 experience, please chip in if anyone also noticed the same with gen3.

Once in Stage 4, you drive at highway speed (55-65 MPH) and keep the MPG above 50. With a steady foot moving the accelerator very slowly (to adjust for hills), you will enter Stage 5 (fully calibrated) in five minutes. Basically drive like grandma with an egg between the pedal and the foot.

Once in Stage 5, you will notice the MPG is higher than before for the same speed. You can even go faster for the same MPG as Stage 4.

 

I am confused. This Prius seems to have a lot of funny quirks to deal with.

I live at 7000 feet in the Rockies. The morning temperatures can be well below freezing for 4-6 months of the year. I do not have a garage; my vehicles live outside.
When I leave my driveway, I have to climb two hills to get to the paved road.

I am not interested in "hyper-miling,' but neither am I interested in damaging my Prius, or becoming stuck in my own yard.

Is the suggestion here that I get an engine heater for my Prius? .. or is it simply to allow a couple of minutes of warm-up time in the winter?

 

if you're a couple of degrees below freezing then the EBH would help, but probably not a huge difference. if you're >10 degrees below then it will make a bigger difference.

The only warm up you really need to do is the 50 seconds after startup. you can hear when the 50 seconds is up (engine note changes, or engine stops) and from that point driving normally would be better than letting it sit and warm up.

 

Most people I've seen with a block heater do it mainly for extra MPGs. My suggestion would be to do whatever you do for any other car you might own; if you like having the car warm and ready to go when you leave, get the EBH. If you don't mind it being cold when you start, it's not going to kill the car; it's designed to take good care of itself. It's probably better than most cars, since it will try to avoid putting a load on a cold engine, for that matter. On the other hand, that can put a big drain on your MPGs, since that means the battery has to provide most of the power, which is less efficient than driving straight from the engine. Most people will recommend accelerating quite slowly for the first minute or two until the car makes more engine power available to you.

Now if you live at the bottom of an on-ramp for the interstate, or if the first thing you do in the morning is drive straight up to the nearest peak on the steepest road you can find, a minute or two to warm up or an EBH wouldn't be terrible options to help the engine so it's ready for that sudden heavy load. But it really depends how much you want to baby your car.

 

Flaninacupboard, macman408:
Thank you both for your courtesy, and especially for the detail provided by macman408.

 

Isn't that simply the heretical mode?