Prius C warm up stages

Makes me wonder if you would have automatic stage 4 like gen 3 or would have to the 'dance' like gen 2 since its the same engine.... Good question!

 

FYI,
Following is an interim report from Japanese Aqua forum.

• The ignition timing is normal in S1a, so no more EV drive in this stage, and the duration is now approx 90 seconds instead of 55 seconds on Gen3 Prius.
• If the coolant temperature was below 40C after the S1a, the ICE continues to run until the coolant temperature becomes 40C, same as Gen3 Prius.

Ken@Japan

 

Ken

Not sure that I am understanding but, this has been my experience so far with initial startup...I have a scanguage II and monitor battery amps and I have noticed that no matter whether the ICE is warm or cold the engine still comes on after initial start and there is a period of time where when I start driving the Amps skyrocket to 80 or 90....then between 30-60 seconds later there is a slight change in engine speed and "feel" and the engine begins charging the battery (confirmed by scanguage) and propelling the car...this can significantly deplete the traction battery SOC. I believe this is when the car is in S1a?

"Stage-1A is the time it takes for the O{2} sensors to begin working and controlling the fuel-air mix and typically lasts 45-60 seconds. During this time the engine runs a rich mixture and if the Prius accelerates, most of the motive power comes from the traction battery. Different models of Prius behave differently during this phase"

Question 1: Is my assumption correct and what is the best way to handle this stage...start driving or wait until the ICE transitions back to charging the traction battery and providing propulsion?

Question 2: Even when warm (water temp above 104F) does the car revert back to S1a to get the mixture correct and then move to S2 or S3?

Sorry if I have this all wrong. I am just trying to understand the behavior of the car and drive for most fuel efficiency...

Thanks

-M

 

Ken

I think you already answered my questions with this post about the gen3 warm up stages...great info! I just needed to search a bit more...

thanks!!!

-M


The Stages:

S0:

it is from power on until the ICE starting for warming up (approx 12 seconds)
you can enable the EV-Drive Mode during this S0, if the conditions are allowed so (refer to your owner's manual)
the EV-Drive Mode can not be turn on when (1)the temperature of the hybrid system is high (ie; the hybrid battery is above 46C), (2)the temperature of the hybrid system is low (ie; the hybrid battery is below 0C), (3)the hybrid battery charge level is low (three bars or less), (4)the windshield defogger is in use or (5)the engine coolant temperature is below 0C (maybe 20C on the US Prius)

S1a:

when the start coolant temperature is below 40C, the warming up starts and continues for approx 50 seconds after S0.
you can not enable the EV-Drive Mode during this S1a.
the ignition timing is very late, after the top dead center. therefore the engine does not have enough power to drive Prius or charge battery.
basically, Prius can not use the engine power when you drive. Prius is driven by battery power and the battery is discharged.
it is good idea to drive slowly or stand still warming up in this stage.
when the start coolant temperature is between 41C and 60C, Prius is in this stage, but the engine does not start automatically.
when you press the accelerator (including driving), the engine starts and runs for approx 50 seconds or until the coolant temperature reaches 65C. the ignition timing is very late too.

S1b:

this is an extended warming up stage.
you also can not enable the EV-Drive Mode during thisS1b on Gen3. (you can enable the EV-Drive Mode on Gen2)
the ignition timing is now normal, and the engine is able to provide power and charge battery.
you are now ready to drive without any penalty of battery discharging.
( A ) if the the coolant temperature is still below 40C after S1a, the warming up continues until 40C.
( B ) if the the coolant temperature is between 40C and 50C after S1a, the warming up continues until 50C.
( C ) if the the coolant temperature is between 50C and 60C after S1a, the warming up continues until 65C.

S2:

after the S1a or S1b, Prius goes to this stage.
Prius acts as normal until the coolant temperature becomes 70C (going to S3).
The EV mode speed is limited below 10 mph on the NA Prius.

S3:

when coolant temperature becomes above 70C, Prius goes to this stage.
Prius acts as normal, but Prius requires an "idling check ceremony".
The EV mode speed is now allowed up to 25 mph on the NA Prius.
the "idling check ceremony" is done during an accelerator off gliding for several seconds on Gen3. (on Gen2, Prius needs a complete stop or very slow walking speed for the ceremony)
the engine continues to run during the several seconds ceremony.
after the ceremony, Prius goes to the S4.

S4:

Prius now completed the warming up stages and in a full normal condition.
if the coolant temperature is above 60C on power up, Prius is already in this stage.
note: this is not a complete list yet and it is based on JP Gen3 Prius, therefore "subject to change" and may not apply other country's Prius.

 

Ken, thanks for the useful information. If any other difference on the remaining stages has been identified by the Aqua forum users, please let us know.
Maxwell

 

That is some nice info. Almost like decoding DNA.

The variables are similar to what I experience on the Prius C

Do these stages compare or are they the science on the C?
or is this strictly for gen3?

 

Ok... That is...so technical... In terms understandable by normal humans ;-) What "ceremony" should I partake in so I let the Prius go through the warming up stages in the m ost fuel efficient way?

Should I:

a) Start the car (i have the blue button in my Prius C Three) than wait 55 seconds?
b) Start Rolling very gently (pulsing in EV mode only) for the first 90 seconds? What indicator tells me the car is in stage 4?
c) start driving normally?

I do really short commutes (less than 2.5Km), so i get low MPG. Maybe I don't let the car go through the Ceremony properly?

Thanks

 

I hit the highway from my home, about 2 miles, every morning (~55-60F). I tried to go through all necessary stages, if I understand the stages correctly. I start the car, the engine starts running for a while, it shuts down and EV mode light turns on. Then I drive in EV mode in this 2 miles and I don't hear the ICE running. However, when I step on the pedal entering the highway (MID showing my car is in the power range), the trip information display showing me that the MPG drops to ~12.5 which is not normally does when I drive my car uphill in the afternoon with the hybrid system going in power range and the displaying show ~25 mpg. I stop pushing the pedal when the indication shows me the power area is full.

Did I have the engine warm up enough? Did I do anything wrong during warm up? What is the correct way to warm up the car in this case? Thanks.

 

Great info Ken. Thanks.

 

It makes WAY more sense and you'll actually know what's going on/what stage you're in if you use something like ScanGaugeII : Linear Logic - Home of the ScanGauge, Torque app for Android + appropriate OBD2 dongle, etc.

 

Can the Prius be driven straight out of the garage normally? im the type of person that winter or summer I hop in, start my car and back out of the garage while fastening my belt and down the street I go.. to the freeway which is less than a mile from home...

in winter can the car get into S1A while im trying to get on the freeway causing me grief?

pardon me if im lame but I have no owned a Hybrid before and still researching what it will be like to have one..

I see people making reference to scangauge.. I have an SG-II I bought 5 years ago, will it work on a new Prius or will I have to get a new SG-II ?
-Christopher

 

When you start the engine, you can drive however you want.
If it is in warmup stages, most of the acceleration comes from the battery.
You wont harm anything.

Not 100% on this, but the scangauge should be compatible.
New just might have more features.

 

Unless your driveway exits directly onto the freeway I think you're safe!
After a mile the car is ready for the freeway, and will warm up quickly at those speeds. You may not be able to use a lot of the newer gauges on a 5 year old SG, but it should work fine for temp and basic stuff!

 

This help explain why my EV cuts off early sometimes, I'm still in S2. Thanks for posting this.

 

Finally got a Scangauge - still haven't quite decided where I will permanently mount it and so far all the new data is as overwhelming as the standard displays were when I first got the c.

Just out of interest - have any c drivers verified how closely the Gen III stages match how the c behaves? I'm fairly sure my Southern Hemisphere c is singing its own song anyway, but I'm intruiged to know what's "a c thing" and what's an "Australian market" thing.