Gen3 warming up stages

Ken, great job. Thanks for the info.

 

Hi Ken,

I have a uk model 2010 Prius and from start up, whilst driving at slow speed for the first couple of minutes, the energy monitor shows red arrows from the engine to the front wheels and the battery. This appears to be contrary to the comments in Stage 1a above. Do you think this is a false indication?

John

 

Wow, Gen3 is a lot easier to get into S4 especially from S3.

 

In the Gen 3, does coming to a full stop trigger "idling check ceremony" quicker as opposed to during pulse and gliding?

 

So if stopped during warmup and reach 60C, I can power off/Ready and be in Stage 4?

Does ECO mode impact the stages, or just change shut-down and re-warm cutoff temps independent of the stages?

EV Mode available in S2 through S4 with the same conditions as S0? When does EV Mode limit go from 10mph to 25mph?

Engine-off glide available in S3 (but not earlier?) if 25mph<speed<45mph? (gen2 34<speed<42...)?

Great info. Thanks so much.

 

2010 Prius Warm-up Stages
With Notes on Their Significance and Detection
Selected 2004-2009 (Gen2) Differences Noted

2010 (Gen3) Prius continues the Gen2 preference for emissions control over maximum fuel economy, evidenced by limitations imposed prior to completing warm-up. Owners can mitigate these limits by understanding the warm-up stages and the associated limits on Prius operations. Mere understanding of Prius behavior is also of value to the owner.

All references to temperature refer to engine coolant unless otherwise noted.


Unlike prior versions, if Gen3 enters Ready Mode at or above 60C/140F, the warm-up process is avoided and Prius is in Stage 4 (S4).

Stage 0 (S0): An opportunity to enter EV mode* without the warm-up cycle if conditions are met. S0 begins upon entering Ready Mode (below 60C/140F), and ends when the engine starts (approximately 12 seconds later unless EV mode activated).

Stage 1a (S1a): Initial warm-up with late ignition timing and diminished engine power. Engine-off at stops: No. Engine-off gliding: No. EV Mode: No. Unless warm-up is avoided, S1a begins at the conclusion of S0. S1a terminates as follows, based on temperature when S1a begins:

At or below 40C/104F: approximately 50 seconds after the engine automatically starts [more testing at extreme cold temperatures needed?]

Between 40C/104F and 60C/140F: approximately 50 seconds after the engine starts (engine start delayed until accelerator pedal is depressed), or earlier if temperature reaches 65C/149F.

With a ScanGauge II (SGII), S1a is denoted with IGN=-10. Without SGII, listen for an audible change in running.

S1a is the worst stage because not only is Prius operation limited, but the engine does not even produce significant power unless power demand exceeds the HSI ECO area, and high demand on a cold engine wastes fuel and may shorten engine life. One should drive slowly or sit and charge the battery during S1a for optimal fuel economy.

Tip: If stopped at or above 60C/140F, power off then re-enter Ready Mode to reach S4.

Stage 1b (S1b): Continued warm-up with normal ignition timing and power (still no EV mode in Gen3 whereas the Gen2 allowed EV mode in S1b). Engine-off at stops: No. Engine-off gliding: No. EV Mode: No. S1b is much better than S1a because the engine will power the car and the generators normally, but it still cannot engine-off glide. This stage is avoided if temperature exceeds 60C/140F when S1a ends. Otherwise, S1b begins when S1a ends and lasts until the following points depending on engine coolant temperature at the start of S1b:

• below 40C/104F: until 40C/104F. (I got engine off at stop with 103F, but msantos reporting 46C/115F for this transition on his Canadian model. Need more data...)
• between 40C/104F and 50C/122F: until 50C/122F.
• between 50C/122F and 60C/140F: until 65C/149F.

With SGII, note the engine coolant temperature when IGN=-10 changes to a positive value, and note the S1b termination point from the table above. Without SGII, limited gliding capability or EV mode availability would indicate S2 has begun.

The Gen2 begins S2 at 40C/104F. So the Gen3 sometimes delays S2.


Tip: If stopped at or above 60C/140F, power off then re-enter Ready Mode to reach S4.

Stage 2 (S2): Engine off at stops: Yes. EV mode: Yes* This stage starts when S1a ends at 60C/140F or more OR when S1b ends. It concludes when temperature reaches 70C/158F. S2 is much better than S1b because engine-off gliding is available, provided the glide begins between 25 and 45 mph. On the Gen2, engine-off gliding only occurred in S3 (limited) and S4. Pulse & glide technique is thus available within limits (25 to 45 start point) in S2.

With SGII, watch engine coolant temperature for the start of S3, then watch for a good idle check glide opportunity. Without SGII, attempt the idle check glide; if it occurs, you were in S3 but are now in S4.

Tip: If stopped at or above 60C/140F, power off then re-enter Ready Mode to reach S4.

Stage 3 (S3): Idle check stage. Engine-off gliding available if glide begins between 25 and 45 mph. EV mode: Yes* S3 raises the EV mode speed limit from 10 mph to 25 mph. More importantly, it allows the idle check (rough shut down) to occur, which is the normal entry to S4 and full operation. In the Gen2, the idle check required a stop (or nearly so) of a few seconds, but the Gen3 just needs a glide without the accelerator pedal depressed for a few seconds. Once the engine shuts off, S4 is attained. Query: must the idle check occur below 45 mph?

If you can glide engine-off starting below 25 mph, you have completed the idle check and are in S4.

No advantage to power off/Ready Mode tip in S3, since idle check ends warm-up anyway.

From what is included here, one could argue that S3 is merely an ending to S2, but I have retained S3 because there are probably differences not mentioned, and for consistency with Gen2 nomenclature.

Stage 4 (S4): Full operation. Engine-off at stops: Yes. Engine-off gliding: Yes. EV mode: Yes* Engine will run if engine coolant falls below _C/_F (40C/104F(?) if in ECO mode) until that temperature reaches _C/_F (_C/_F if in ECO mode). [I saw these temps reported here, but cannot find now.] Gen2 defended at 63C/145F until 73C/163F was reached. Full glide availability is a major advantage of S4.

The availability of other driving techniques such as warp-stealth, warp-neutral, and super highway mode (SHM) is not yet addressed here. It seems unlikely they could be employed prior to S2, with some as late as S4 for unrestricted use?

*Notes on EV Mode

Recommended uses:
Moving around the driveway or parking area
Drawing power in expectation of major regenerative opportunity (e.g., about to crest a mountain)

EV mode conditions:
Engine coolant at or above 0C/32F (20C/68F on US models?)
Windshield defogger not in use
Hybrid system (HV battery) in the range 0C/32F to 46C/115F (no x-gauge yet?)
HV battery state of charge (SoC) at or above 4 bars
Speed below the applicable limit (10 or 25 mph)
Not in S1a or S1b

EV mode terminating conditions
Failure to meet initial conditions (do limits differ?)
Excessive power demand

EV maximum speed by stage:
S0 and S2: 10 mph
S3 and S4: 25 mph (10 mph if engine coolant below 70C/158F)

Note: Engine-off at stops and Engine-off gliding will not work while the window defogger is on, even if in a stage where they otherwise would work.

I take most of this from Ken@Japan’s fine work, and from reading the Gen2 Five Stages ‘literature.’ Without a doubt, further refinement of our understanding is needed. Please share your knowledge and experience, especially where the preceding explanation seems incomplete, incorrect, or misleading.

I have a Gen3 and a SGII, but have not really tested the guidelines above. So this is more an attempt to start a refining process within this community than a presentation of results. You are welcome to PM revisions to me or just post them up and I will incorporate by editing my post.

 

What I find odd (and frustrating) is that S0-S1a is effectively EV mode while the ICE warms up - but you're not allowed to actually select EV mode and keep the ICE off, even if you just want to move 20ft.

Why not? If it was a problem for the electric motors, the car shouldn't be allowed to move at all until reaching S1b or higher...

 

Excellent point, Tom. The problem as I see it is that we cannot tell the car our 20-ft intention, and it is a slave to emission control, assuming we are starting our commute or whatever. In the summer, you are more likely to meet the EV mode conditions in S0, but in the winter, unless already pretty warm, you are stuck with the warm-up cycle.

It is an even bigger issue for the PHEV folks who would like to tell the car when to use the extra batteries, but, depending on the PHEV kit design, may be stuck with warming up the ICE only to shut it down.

 

From a driver, non-technical point of view what does this mean to me when I get in the car, press start, get 'Ready', and go driving? Are any of these warm-up stages important--or just interesting to note? Thanks.

 

They are important for hypermilers. Just get in the car and drive, it will take care of itself .

 

Ken, I can confirm that EU gen II Priuses are also able of engine-off gliding in S2. At least mine is .

 

Good stuff indeed. My comments below:

Anyhow, I also wanted to make a couple of observations that may help a bit as I believe there remains some detail to be added.

With regards to S1b:

As I had mentioned before, at the moment 40C/104F means very little to me as I yet to see the lower S1b threshold occurring at that value. I do see it happening at 46C/115F though...

Also, I believe there should be (at least) an alternate state that provides an override/inhibit of some of the features on the account of the OAT (Outside Air Temperature).

This is because when the OAT is below -20C/-4F (approximately), ICE off at a stop and ICE off glides are literally impossible even when the ICE temp has reached and exceed 70C/158F.

By the same token, WS and SHM on my Gen 3 are also not available when the OAT is that low (at least in my car)... again, this is observable even when the ICE temps exceed 70C/158F.

I'm beginning to suspect we have something interesting going on with the Gen 3 that we did not notice with the Gen 2 Prius... particularly with regards to the OAT element. If this is the case, then we may have to rethink the sequencing of the warm-up stages especially if it becomes anything close to the warm-up nightmare the HCH-II has.

Cheers;

MSantos

 

what's the typical time in S1b?

 

I think since it's temperature dependent the OAT and how fast you are driving would be the most important factors. Most mornings I set in the driveway until I'm out of S1a and by the time I reach the stop light about a mile down the road the engine will stop if I have the heating system off providing OAT is in the high 30s (degrees F) or above. So that would be about 3 min, somewhere in there it reaches a point when the engine will shut down when stopped but the ICE temp is still only 115 degrees F or so. I would still need to drive at approximately 40 MPH for another couple of miles to get the temperature up to 140 and enter S2. I use ECO but I think Ken indicated that the mode may not matter.

 

[Tip: If stopped at or above 60C/140F, power off then re-enter Ready Mode to reach S4.]

Does this mean that at a stop sign I should turn off the car and then turn it back on?

Also, when I first leave the house in the car I have two options for starting out: I can drive about 20 meters to a stop sign and then turn onto a residential street, where I usually am forced by traffic to accellerate in the upper part of the bar before power and go about 150 meters to another stop sign. The next stop sign is about 300 meters, and the car will often, but not always glide up to this stop sign. By the next stop sign, the car will pulse and glide from 40 mph. Where in this process would I turn off and on the car to get to S4?

My other starting option would have me driving without stops at whatever speed I like (speed limit 10 mph) for about 500 meters before the first stop sign, then about 50 meters to the next stop sign and 300 meters to the next.

So should I drive the second route at 10 mph and then shut off/restart the engine at the first stop sign to get to S4?

The car is garaged and the garage temperature is typically in the 50s in the winter and the high 60s in the summer.

A second question: on the way home, I've been using EV mode in the last half mile/one kilometer or so and parking in the car for the night with 3 or 4 battery bars. I've figured, and maybe read, that since the ICE will recharge the battery in warm up anyway the next time it's driven, this is OK. Is this wrong?

Thank you everybody for all of your knowledge and your willingness to share.