Paul. I have looked into the Ford EDIS ignition system
aeafter reading about it on the newsletter.  I bought the
EIDS-4 which is"electronic distributer for four cylinder"
It reads a 36 tooth minus 1 toothtrigger wheel to do the
timing which is 10 degrees BTDC from the installedposition
of the trigger wheel with the missing tooth aligned with
TDC.Mounting it 6 degrees advanced will give a 16 degree
BTDC spark event.


I alsobought the 4 coil pack which is
for lost spark use.  The lost spark wires thetwo plugs in
series connected by the engine block giving one
sparkelectrode to shell and the other shell to electrode.
The majority of the energygoes to the plug under
compression with little expended on the exhauststroke plug.
I also bought an assortment of EEC-IV Ford engine
computers.  Theycost from $1 to $44 dollars on E-Bay.
These were chosen by pre codedignition key(1996) and after
1988 to be mass airflow with 1993 thru 1995 mypreference as
these also work sequential injection and multi spark for
thelower rpm range.  They run off the stored tables at wide
open throttle and belownormal operating temp.  In betwen
they use algorithms to determine lamda=1from a wide band
oxygen sensor.



Any oxygen sensor voltage between .33 and .80 doesn'tchange
mixture, a pretty leniant range.  The ignition timing
comesfrom the variable reluctance sensor as it falls thru 0
volts to the EDISmodule which conditions the signal and
sends it to the computer.  Thecomputer (EEC-IV) sets a
pulse width signal output back to the EDIS every 5spark
events which advances the timing to a maximum of 59
degrees.  This rangeis a result of the binary count,
nothing to do with wanting that muchlead.  The MAF sensor
and injectors have to be a matched set such as an 80
MMmeter and 19 thru 24 pound injectors for the table values
to be correct.

The Map sensor is open ended and used for
barometric corrections and in someinstallations reads the
manifold pressure and sets the barometric presure atkey on
and wide open throttle.  If the throttle position sensor is
not usedonly the look up tables are available for mixrure
control making the oxygensensor also redundant.  The tables
devide the airflow into 30 divisions withmultiple tables
for all the perameters sort of like a multiple axismatrix
nor just a single table.  The computers have a 60 pin
connector and iffrom an economy box type car about 40?  of
the pins are unwired.  There aretwo types of injector
firing for V6 and V8 engines, both sequential andfiring
every injector on a cylinder bank called bank fire.  IT
appearseither system works the same on a rotary since we
need only two injectorevents.  The processor generates a
result aparently in 1 microcecond when usingthe tables ans
3 microseconds using the algorithms.  The avarage
injectorduty is 30% and maximum of 50% and mid RPM pulse
width is 3 milliseconds.


snips..........


george grimes

Stock systems are not a bad way to go but in the air leaning is the
problem. Perry has been flying a stock RX7 computer for years. O2
sensors are fouled by 100LL but Perry tells me the system defaults
to open loop. Open loop is too rich so the fuel burn suffers.

Paul Lamar


George Grimes -

Very interesting details.  I will need to remember to look you up when
it comes time to do Fuel Injection and Ignition.  You seem to know a
LOT of details about the Ford components.  That can/will come in
handy, especially since they are proven components (thousands of
working production parts).  The trick will be getting them tuned, but
don't be dissuaded from trying.

-Vince Orton