Throttle-by-Wire

[Programmer]

Well, kinda, not really...this is how it really works.

Fuel is supplied to the injectors through fuel rails inside the cylinder
heads. Also supplied to the injectors is high pressure engine oil. As the
computer determines that a cylinder should fire it signals the Injector
Driver Module. The IDM sends a 110 volt pulse-width modulated signal to the
injector solenoid. When the injector solenoid is actuated, it opens a poppet
valve which allows high pressure oil to flow into the intensifier piston.
The intensifier piston is forced down, pressurizing the fuel inside the
injector. When fuel pressure inside the injector reaches approximatly 2700
psi, it causes the injector pintle to rise off its seat and fuel is injected
into the cylinder from the nozzel. As long as the poppet valve is open and
oil is flowing into the injector, fuel will be injected.

The computer controls how long the injector solenoid is energized
(pulse-width, or time on in milliseconds), but it also determines the
pressure of the fuel being injected by controlling the pressure of the oil
(IPR duty-cycle, or the percentage of time on vs. off--AKA dwell) in the
cylinder heads. The computer determines this based on engine load and driver
demand by monitoring various sensors. Since the cavity at the top of the
intensifier piston is seven times the size of the fuel cavity at the bottom,
fuel is injected at a pressure seven times that of the computer-controlled
oil pressure--oil pressure 3000 psi = injected fuel pressure 21000 psi. Due
to the high oil system pressures, the spring which closes the poppet valve
once the injector solenoid is deactivated has to be very strong--and because
of this, the solenoid needs to be 110 volts. Once the poppet valve is
closed, spring pressure returns the injector to its normal state and the oil
is exhausted into the valve cover area to return to the sump.

Lyndon.


----- Original Message -----
From: "mike beebe" <mikebb1 at hotmail.com>
To: <diy_efi at diy-efi.org>
Sent: Saturday, January 19, 2002 6:58 PM
Subject: Re: Throttle-by-Wire


> the powerstroke does not use an injection pump. it controls an electric
> solenoid in the injector that stops oil flow through it force it to
> pressurize the fuel and popping the injector open. so it is rather easy to
> control the diesel with TBW.
>
>
> >From: "Programmer" <nwester at eidnet.org>
> >Reply-To: diy_efi at diy-efi.org
> >To: <diy_efi at diy-efi.org>
> >Subject: Re: Throttle-by-Wire
> >Date: Sat, 19 Jan 2002 17:58:24 -0700
> >
> >Ok...for the nit-picky folks out there, the Powerstroke is "drive by
> >wire,or
> >accelerator by wire, or fuel by wire, or...". Either way you look at it,
> >there's no direct
> >link between injection pump and accelerator pedal.
> >
> >So as my daughter would say ... "whatever" !!
> >
> >Cadillac ran a ISC motor based on computer inputs...and this system alone
> >could put your car into the wall on an icy road if it malfunctioned. It
> >physically pushed the throttle linkage. I don't think you'd get me into a
> >TBW gas job without my steady hand on the key.
> >
> >Lyndon
> >
> >----- Original Message -----
> >From: "Greg Hermann" <bearbvd at mindspring.com>
> >To: <diy_efi at diy-efi.org>
> >Sent: Saturday, January 19, 2002 12:21 PM
> >Subject: RE: Throttle-by-Wire
> >
> >
> > > TBW is indeed a tricky thing to do right. Thing is--I would
_seriously_
> > > question the qualifications of the OEM's to be doing it right long
> >before
> >I
> > > would question the qualification of _some_ of the folks here !!
> > >
> > > And, the TBW on a Power Stroke diesel isn't particularly relevant, all
> >it
> > > controls is fuel, no (air) throttle on a diesel, remember !!
> > >
> > > Greg (PID= Proportional, Integral, Differential, or would you rather
> >work
> > > with Fourier or La Place transforms?)
> > >
> > >
> > >
>
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> > >
> > >
> >
> >
>
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