034 EFI

[auditude at neta.com]

On 4 Dec 2001, at 18:57, Huw Powell wrote:
>
> > Ok, I read Javad's recent post describing it as much easier to install the
> > efi and a CIS system a car that didnt have it.  I understand and accept
> > that.  But it looks like my current thought process is that I still have to
> > integrate the ignition side of the MAC11 setup into the 4ksq.
> >
> > What I'm wondering is how big of a job is it to swap over just the ignition
> > side of a 5kcstq into a 4ksq.
>
> I don't think it is worth it if you've got EFI on the horizon.  here's
> why:
>
> 1. the ignition and fuel system are integrated so you need more junk
> 2. the 5kt ignition system depends on a flywheel sender or cam pins for
> triggering
> 3. the 2.3 (NF/NG) system is separate from fuel system, and uses a 5
> window distributor to trigger it
> 4. You can put in the turbo plumbing, install and fire up EFI, and still
> use the stock ignition system at first.
>
> I don't see the point of installing all that wiring from the 5kt just to
> rip it out later.  Just do the turbo/EFI work, get it smogged, take a
> breather and start looking for your ignition system donor vehicle (there
> are many!)
>
> I haven't really btdt, but I did once spend a long afternoon on Marc
> Swanson's garage floor separating out that insane 5kt wiring harness
> from all the stuff that isn't even fuel or ignition related in it!

That's a very good argument against bringing over the MAC11 stuff.
 I'm convinced, especially if I can get it running with the stock 4ksq
ignition system for the meantime.

I'm now left wondering if there are any standalone ignition systems
that would be usable.  I'll search around for that.

Maybe I can get a J&S Safeguard and run the stock 4ksq ignition
with it?  That could be where the money not spent on a MAC11
chip mod can go.

I used to think a complete stock MC-1 swap were the best, as
opposed to fuel side only, just add a turbo and manifold, and many
other "outside the box" methods of changing a n/a to turbo.  But
the simplicity and performance of efi seems to open up more
possiblities.

I did think of one question about 034 EFI and systems like it.  If the
injectors are pulsed so that only some of the time they are
spraying, and it's not timed to valve opening, does that mean there
are times when the combustion chamber gets less fuel than other
times?  Is the air sitting in the intake port "on average" the right
mixture, and that's why it's okay?

I was thinking if it's firing each injector 5 times per cycle, then it's
not a situation where the injectors are pulsing so rapidly that the
mixture is the same.  Does it mean that in a 360 degree rotation of
the engine, each injector's pulses are evenly spaced?  Every 72
degrees, each of the injectors squirts for the prescribed pulse-width-
modulated time?

I think my paradigm is that each timed burst of fuel consists of the
injector quickly opening and closing repeatedly for a certain period
of time.  I'm thinking that the controller fires each of these injectors
in this matter, one after the other, until all 5 fire, and then stops,
this being one cycle.  These cycles are repeated as soon as is
necessary to support the air being sucked in.

But maybe it's not like that (I have no idea).  Maybe one tiny
opening and closing of the injectors is one pulse, and it's these
little tiny squirts of fuel that are sequential.  In this scenario, all the
injectors start out closed, the first one opens and closes very
quickly, followed by the second and so on.  At any given time, only
one injector is open, but they are all chattering away at the same
rate, which is 1/5th of some percentage of their duty cycle, that
percentage being determined by the controller.

So, there's just one "level" of modulating going on.  It's not like the
frequency is set by the controller (opening and closing at a certain
rate, for whichever injector is active), and that frequency is sent to
one injector at a time.

Another way to say it is, is this a rotation of _open_ time among
the injectors, or is it a rotation of _frequency_ time?

This probably doesn't make much sense, but maybe someone will
recognize what I'm trying to understand.

Thanks,

Ken