Hymotion and 52 MPH EV Mode -

Momentarily cutting 12V power to the ICE ECU will cause the car to enter high-speed stealth. That's what I understood it to be anyway.

I'm going to try it at some point in the next few weeks for experimental purposes.

Nikki.

 

i also understand after reading the website that it wil set a DTC or dead sign

 

So which would be better cutting the fuel or cutting the engine ECU? Is there a difference?

 

i gues the ecu
gutting the fuel will stil start the ICE buth without fuell.. not sure if thats so good
even if it only try;s ones and then sets a dtc or so.

not sure...

cutting the ECU all togetter wil prefent any ICE movement i gues...

 

Reading what Hobbit has put on his website it's only a temporary cut in the 12V ECU power that results in the ICE cutting off until the next car reboot. I suspect cutting it off altogether would cause more problems.

As for which mod is the best, I would probably go for the 12V cut rather than the fuel-pump cut. As Hobbit pointed out, the fuel line is pressurized, and cutting the pump line cuases the engine to splutter a lot before completely cutting out. I suspect there's the quick and dirty way to get 52mph EV mod.

I'm going to try it at some point, but I must admit that I'm a little wary of the whole thing when compared to the 70 mph Ewert mod. But, without modifiying the battery setup I think it's the only way for most owners to get a higher EV only mode unless they're accomplished pulse and gliders!

Nikki.

 

What is it specifically about 52 MPH that all these guys are
going on about? I never understood that. 52 with the engine
still has MG1 going about -8000 rpm, no big deal and not even
near the dreaded 10,000 that strikes so much fear into them.
[We will note the reminder that pressing the go-pedal while
stopped in park does an engine run-up to 2400 RPM, which has
MG1 spinning over +8000 RPM so that's clearly well within its
safe design limits..]
.
Cutting the engine ECM is instant because the hybrid controller
immediately loses CAN communication with the engine ECM. That
causes it to give up on using the engine on the spot, instead
of waiting for the fuel pressure to run down and the engine
controller to finally admit "hey, I got a problem over here".
If the PHEV CAN-spoofer board kicks in soon afterward with a
mode $04 clear-DTC command the triangle can be extinguished
but that doesn't convince the hybrid controller that it should
try the engine again until *it* gets power-cycled. Meanwhile
all your emissions monitor results are toast and it may even
reset some other things like learned fuel maps.
.
If you're playing with this, note that there are at least
*three* power leads to the engine ECM: +B at E7-4, black, main
"ignition" power; +BM at E7-5, gray wire, special power to the
ETCS throttle motor; and BATT at E7-6, red, always-on memory
keepalive. Breaking +B is sufficient.
.
_H*

 

and breaking that line will not set a DTC or give a deadsign on the dash?

only problem is that if you want the ice to start again at some point you have to do a power cycle?

 

It *does* set a DTC. Immediately. And requires a full restart
to recover from.
.
I don't know how many different ways I can say it...
.
_H*

 

yes ok set a dtc
but there where more then 1 question in my post
also light up the dashboard triangle of dead or not?
or is that only going to light up with the fuel cut hack?

 

Thanks for the update.

 

_H*

Would it be safe to cut +B power during drive? Restore power after a few seconds? As pointed out earlier, removing the EFI fuse is one way of triggering this. In that case, +B power is lost, and of course a fuse could blow during drive. But if you compare this with just cutting +B, the difference is that in this case all the other systems on this fuse are still powered. Otoh, the +B connector could potentially come loose during drive, and it would be a strange design if something bad happened as a consequence.

Has anyone actually tried switching +B power on/off during drive?

If switching on/off power feels bad, another idea could be to disconnect the ECU from the CAN-bus. That should also trigger the "drive on motor mode", as Toyota calls this error condition.

 

Hi Guys,

I'm sure that several people have already posted about this, but there are a few things about this forced stealth mode button you should know.

You should know that using forced stealth mode sets an OEM diagnostic trouble code (DTC) which requires clearing /all/ stored diagnostic data to remove. That includes all stored service data and emissions data (which is legally required for emissions standard testing). It's not the end of the world, but since most states use OBD2 for emissions testing it can cause the vehicle to fail the emissions test (hilarious yes, but true) if forced-stealth mode has been used recently.

You should also know that driving the vehicle faster than 42 MPH in forced-stealth mode risks over-revving the drivetrain. Please see ( www . eahart . com / prius / psd / **Remove the spaces--couldn't post the full URL**). Note how if you drag the MG2 dot beyond 42 MPH the red zone becomes critical which indicates the motor is potentially being over-revved (Yes, it's true. Argonne National Labs has verified it). This can cause long-term vehicle damage. There is a reason why Toyota always forces the ICE on when you go above 42 MPH regardless of the accelerator pedal--just because Toyota allows the vehicle to go above 42 MPH in forced-stealth mode does not mean it's good for the car. Forced-stealth mode (also known as limp-mode) is designed to be used in emergency situations (critical engine problem or ran out of fuel) as an absolute last resort.

You should also know that in the event of an emergency where you need the full power of the Prius motor + engine, you will not be able to use the engine until you completely stop and restart the vehicle. That means that if you have to get out of an intersection quickly you will not be able to (you'll only have at maximum 21 KW from the motor). This demonstrates a pretty big safety risk.

In the event that you forget to turn the car off and exit forced stealth mode in time (when your PHEV pack depletes for example), the OEM pack (if you are using a CalCars style conversion) will drain into the 30s before the vehicle finally sputters out. This causes extra strain on the battery and will reduce the lifespan of your OEM battery.

If you're OK with all these things then it's up to you if you still want to use it but I thought I'd lay out the risks.

Andrew