2010 Prius Warm-up Stages

[msantos]

Originally Posted by ksstathead

...
When you say lower theshold, are you referring to the S4 section where the ICE restarts, or to the various mentions of 40C in the early stage transitions?

I was referring to the multiple references of 40C in the early transitions. 46C (114.8F) is the lowest transition temperature I've recorded.

Cheers;

MSantos

[msantos]

Originally Posted by Right Lane Cruiser

...
Too bad there is no way to force engine off whenever you want it…

Hi Sean;

Yes, that's true. Not being able to force an ICE shut off does suck a bit though... However, even though I can do it in the HCH-II, I have been choosing against it when the temps are really low simply because the price you pay for a FAS is so darn high and in so harmful in several different ways.

What I am trying to say is that with HSD we are forced to let it do its thing and take it for what it is. But while we can FAS with other hybrid systems (like the Gen 4-5 IMA) it does not mean it is the best option either. In the big scheme of things when it is that cold, it just is... and letting the systems do their thing often produces the better results in the long run.


Cheers;

MSantos

[Right Lane Cruiser]

Manuel, I've also found that engine off coasting is almost useless when the temps are low enough simply because glide distances are almost nil with all the extra friction in play... but being able to force engine off at stops still makes a huge dent in fuel usage. That's the one I'd really like to be sure I could do in a Prius in really cold temps.

[msantos]

Hi Sean;

The problem with FAS on a 2010 Insight or HCH-II (especially nasty on the HCH-II) is that when at temps below 15C (59F) the warm-up stage is reset back to stage 1 for 10-15 seconds after Power-off.

This will happen even when the engine is fully warmed up. So for short stop lights a FAS is not helpful at all since the fuel consumption is going to be higher after power-up and in the process you've dinged your 12V battery quite a bit too.

The other problem in colder temps is that the ICE temp drops like a rock in just 30 seconds so much so that even keeping the ICE ON and in N can slow but not stop the free-fall. The Gen 3 Prius also drops the ICE temp like a rock when it is very cold, so an ICE OFF condition does not help the Prius either. This I verify on a daily basis with a grille fully blocked on both cars.

Cheers;

MSantos

[Right Lane Cruiser]

Hi Manuel -- I see the same with my tiny aluminum block in the Insight-I... but I still find it useful early in the drive when the block hasn't really warmed up anyway. Such as trying to get through the first 10 lights on my route every morning (which occur in the first 3mi). Light timing is (as always) the most powerful tool in the arsenal... but if I have to stop I'd rather cut my losses. Later in the trip it is typically a different story.

[Yoshi]

Originally Posted by Right Lane Cruiser

Too bad there is no way to force engine off whenever you want it…

A thermistor hack will let the engine off if you want.
I will write up it soon for Gen3 Prius.

Yoshi@Japan, aka Ken@Japan

[Right Lane Cruiser]

Hello, Yoshi!! Good to hear from you again.

I wasn't aware that a thermistor hack would work in the 3rd generation. Very cool!

[Yoshi]

Hi,
I just posted yet another thermistor hack for Gen3 on the PriusChat forum.

Enjoy,
Yoshi@Japan, aka Ken@Japan

[Right Lane Cruiser]

As always, thank you for your hugely helpful contributions to the knowledge base.