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I've been using NICE-on (Shift to Neutral if the ICE won't shut off) during warm up on my '07 Prius and I've been asked if it improves FE. My unscientific answer was "seems to for me", but wanted to know if anyone who has a better understanding of the THS ECU would be able to give a definitive answer.

I also had to followup questions regarding NICE-on:

1) If the ECU will transition to stage 2 while in "N". Or more specifically, if while coasting in "N" the collant temp hits the magic number, will the ICE cut off, or will it wait till I'm in "D" to kill the ICE?

2) Will this freek out the transmission or ECU on an '07 Prius going into "D" from "N" at 20 mph?

Hi Dan:

___I have to be very careful with my answers as I am more guessing and remembering past posts wrt the following.

1) The ICE will not shut down in N if it was previously running. A shift back to D should engage AS after a very very brief period once all the temp interlocks have been made up.

2) The transmission is never disconnected but field builds on the MGSet’s may or may not have to be taken into account? I have not read of anyone doing a current analysis on the MGSets while in N to see if they have actually been disabled. In the case of the FEH, I have seen current flows on the FEH Energy screen mimic while in N meaning nothing was actually shut down other then if the ICE is running, it will stay running or if it is off, it will stay off.

___Good Luck

___Wayne

Great questions Dan. I'm looking forward to any and all answers. There is one part of my commute in where I shift to N to avoid using EV mode for a prolonged highway exit (I need that EV later for some extended glides), and wonder myself if there is any risk in doing this daily.

I have an additional question. At the beginning of my commute, I'm fortunate enough to have a very steep decline for 3/4 mile. It's so steep that I can just regen down it..........I don't even need to NICE-on to avoid using gas. It seems like a no-brainer that regen'ing down a hill is preferable to NICE-on, since neither uses gas but regen does power up the pack. But I thought I'd throw it out there since it may not be a no-brainer after all.

Hi Mparrish:

___You appear to be on track with that initial portion of your commute as Regen means Fuel Cut (no fuel) and if you have to slow down for a sign or light, why not. I have to little experience or knowledge of N in the Prius to know so I had better let the Prius II guys and gals answer those questions from here on out.

___About that off-ramp … Can you approach from a slightly higher speed and Warp-Stealth down to 40 and run a std. Glide the rest of the way in with a touch of regen near the bottom or stop if needed? If you can avoid using N with no loss, why consider the shift as it is another distraction?

___Good Luck

___Wayne

Wayne,

Thanks as always for the input.

The off ramp is not your typical ramp, in a good way. I recently added it to my commute. It drops dramatically in elevation underneath both the highway just exited and another highway crossed, only to rise back up to a stoplight on a boulevard at the original elevation. If I time that boulevard stop light, I have another two miles of descent gliding. It's a beautiful thing when I can pull the whole doggone thing off.

But to pull it off I have to warp stealth at the beginning of the exit ramp at around 45-50 mph, increase speed on the downhill to 60-65 mph, and bleed off speed on the uphill so that I hit the light at around 40. That's a good distance above 42 mph, and a good amount of EV. Neutral coasting saves me that EV for later, when I could use it.

But this slingshot ramp is so good that it would be worth using up that EV..........if daily shifting to neutral were problematic over time in some way. We'll see what the Prius guys and gals think.

A buddy of mine could not believe I got 75 mpg on the way to work. So I took him on part of my commute, his first ride in a Prius. After learning about P&G and watching it in action, he said "No Fair! You have a soap box derby car!"

So true, so true. :)

To review quickly, the definition of N in the Prius is to
disable the "gates" that allow the inverters to work. That
removes any control from both motors. A side effect is that
if the ICE is running, it stays running [but drops down to
base idle], and if it's off it stays off. [Including when the
car is rolling above 41 mph, giving rise to "warp neutral".]
.
NICE-on is a convenient second-choice mode for warmup stages,
but even better is to force shutdown with an EV button at the
same times when, if you were in stage 4, the ICE would shut
down anyways. When it's really cold the hybrid ECU won't let
EV mode work -- battery's too cold to be useful, it figures.
So at that point I use NICE-on for the coasts, which doesn't
bring in any torque from the engine whereas a light foot in "D"
actually does [but down in that mega-inefficient range].
Then the game becomes whether or not I can crest 35 mph,
over which backing off the accelerator is more likely to
cause normal shutdown, whereas otherwise it insists on
still running even when coasting/decelerating. That's an
annoying paradox that this car has...
.
_H*

NICE-on is a convenient second-choice mode for warmup stages,
but even better is to force shutdown with an EV button at the
same times when, if you were in stage 4, the ICE would shut
down anyways.:eek: BRILLIANT!. People have been suggesting I get an EV button, but since I didn't want to use the pack, I didn't see the point. Never thought of it as an ICE-off switch. Just to clarify, if I'm have the EV mod and activate it, then feathering can achieve black arrows, or is it just a very light EV mode (like stealth-warp)? Now I just need to determine if I want to start mod'ing my 5 week old car yet :o .

I'd also thought of taking a purest approach so that my bragging rights were based on an unmodified car, but I could just argue that is just like all other Prius just not like the US ones. Since I use my brights flash a lot (popular motorist exchange in Houston :mad: ) I'll have to install the button. Hear that's kinda scary.

Ohh well... Balls in my court now... Thanks for the great tip!

Yeah, an "ICE off switch" is a very accurate description of the EV button. If you feather the accelerator in EV mode it will glide just the same as any other time. The only hitch is that there are restrictions, as this just activates software that Toyota built into the car for every other market besides us. It won't go in if the pack is too cold or hot, if the engine is in the process of warming up, if you demand too much power, etc. I really don't think you can do any harm to the car because Toyota's engineers are pretty much looking over your shoulder and vetoing anything that brings the system out of its designed operating parameters.

Of course they won't stop you from harming your FE by overusing EV mode. But I think you're in good shape if you just use it to force an engine-off coast, or for the designed purpose of moving the car around the driveway without the ICE starting up unnecessarily.

So at that point I use NICE-on for the coasts, which doesn't
bring in any torque from the engine whereas a light foot in "D"
actually does [but down in that mega-inefficient range].
Then the game becomes whether or not I can crest 35 mph,
over which backing off the accelerator is more likely to
cause normal shutdown, whereas otherwise it insists on
still running even when coasting/decelerating. That's an
annoying paradox that this car has...
.
_H*

Excellent points, I've also noticed this behavior when it's too cold to use the EV button (like all of last week). EV won't engage but NICE-on seems to be a good second choice, esp. in stage 2 when it's harder to get no arrows by feathering (it is more likely to jump straight to red+green from regen, bringing in low torque).

I have a 1/2 mile downhill at the end of my morning commute, and when it's too cold for EV, I think I think the second-best thing to do is to get up to 35MPH and get ICE-off rather than crest the hill more slowly and maybe not get up to 35 (with ICE-on the whole way).


Dan - thanks for moving this to a separate thread, and thanks to all who have responded so far! Very informative. :)

Heh... my EV button went in within about a day and a half
of taking ownership. But I just *had* to know what it was
like. It's even sort of blogged (http://techno-fandom.org/~hobbit/cars/prius-log/004.html), not that I ever got time
to really continue on that when I wasn't ranting into lots
of other forums!
.
_H*

Hobbit, Thanks for the tip.

Now I'm looking into the EV Button (can't do the brights override, either OEM button, or CC cancel override).

I've started yet another thread to figure out if using the Engine-Veto (EV) button will increase net emissions.