Steve Powers wrote:
> I was under the impression that with no fuel (i.e if
> you run them out of gas) the current cars as-is 04-05
> models can run up to about 45 MPH with decent
> performance using absolutely no fuel.

You may be referring to my recent experience with running
out of gas and using my 10 mile ev range PHEV superpowers.
http://autos.groups.yahoo.com/group/eaa-phev/message/1042

> I'm very surprised that no one has tried a manual
> shutoff of the fuel injection system. It's just like
> any other fuel injection system in its basic form.
> Remove the injection signal and / or fake it so that
> it thinks it is injecting fuel, and it will still run.
> Have I misunderstood this? I understand that it will
> still spin the ICE between 34 and 45 MPH, but still
> use no gas.

While you could do this I don't think that it would be
very practical for a number of reasons.
- When the Prius detects that it's out of gas it shuts
down the fuel system to prevent partial or incomplete
combustion which could damage the catalytic systems.
Disabling the injectors or fuel pump would most likely
send the car into this same protective mode. When you
are in this mode the dash lights up and numerous DTC's
are set. The car won't recover from this mode until
it is power cycled, so you would need to stop, shutdown,
clear the codes, and then start again to leave this mode.
So it's not something that you could enter and leave on
the fly as you continue to drive. This mode also lacks
the MG1 protection of spinning up the ICE to keep that
motor under 6000 RPM, while this motor is now rated for
a peak of 10,000 RPM (ie. 60+mph with no ICE spin), the
software normally avoids this, thus the 42mph limit.

As Ron mentioned Hybrids-Plus doesn't use the EV-Mode
as a part of their normal PHEV operation. Rather due
to their ability to report arbitrary SOC values to the
rest of the car they can simply tell the car that it
has an SOC of 70% or 75%. With such a high SOC the
car is more inclined to enter and stay in stealth mode,
which is the natural Electric mode up to 42mph. Above
this speed if demand is low enough the car will also
drive in "ICE Spin" mode which is yet another electric
mode above 42mph. With a high SOC you can use "ICE Spin"
mode on the freeway under low load conditions drawing
up to 40 or perhaps even as much as 60 amps (about 12kW).
So, with our current batch of PHEV conversions which
rely primarily on SOC manipulation there is plenty of
mileage gains and electric driving to be had.

> What else would need to be faked out to make the car
> still run if you intentionally shutoff the fuel
> system?

I'm not sure if it would be possible to do this. I
don't think that any of the current PHEV converters
will be pursuing this due to the acceptable performance
under our current strategy, and the potential for damage
and increased dangerous due to poor vehicle performance
without the ability to rapidly restart the ICE.

> Or look what is being done at 99mpg.com. Build a
> whole new parallel dual 3 phase motor controller and
> forcibly take control of the drive motors through your
> own system. But, it needs to be a reversable change
> (unlike the machanical hack at 99mpg.com). I envision
> 2 complete electrical control systems - one for EV
> mode, one for the car as is.

That is entirely possible, I have personally started a
project (no ETA as I'm focusing on the Prius now) which
would add to the rear of a Honda Insight a fully freeway
capable EV conversion. We also saw such a conversion of
a Saturn Vue done by Argon Labs(?) at Hybrid Fest 2007.
This type of setup is called a "Through the road parallel
hybrid configuration" since the gas/hybrid portion is
connected to the all electric portion via the road surface
only. That is the ICE need not produce electric power
directly to support a Charge-maintaining mode and the
electric portion can operate independently or in parallel
with the ICE in a Charge-depleting mode. I really think
that this sort of conversion hold a lot of promise for
transforming traditional vehicles into hybrids and/or
giving them full electric modes of operation.

> Otherwise, someone needs to reverse engineer the
> software and work around the 34 MPH EV mode limit and
> the other power limits imposed in the current system.
> I see it very unlikely that Toyota will provide us a
> new software version for the existing 04-05 cars with
> the restrictions removed. Why would they?

As Ron mentioned it's unlikely that any of us has the
resources to make such modifications to the current
Prius systems. We're pretty confident that Toyota could
do this, but I agree that they are unlikely to make such
upgrades available for the current 2004+ Prius. I think
that they should, what with the 500,000 Prius out there
that could take advantage of such an upgrade. We'll just
have to wait and see what changes are made in the new
Toyota Prius PHEV and if any of the new systems could
be applied to the older vehicles.

> I still think the current mechanical hardware and
> electrical hardware as-is in the current 04-05 models
> could be made to perform in EV mode up to 45 MPH
> (which would motivate a lot more people to convert)
> with no hardware changes - only software and / or
> spoofing of various signals and / or mechanical
> shutoff of the fuel system.

In the end I don't see the 42mph stealth mode limit as
a problem. A larger battery would remain a requirement,
so that would remain a hardware change.

L8r
Ryan



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