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



Vince, In order to alter the tuning of a ford ecu an additional chip is
attached to the J3 service port. Company;s such as tweEECer  and before them
EECtuner provide software to download the ford tables and a chip burner to
make the chip. You can get base software less the data logging for free
from   www.tunerpro.markmansur.com  to see how involved it would be.  The
point to using a mass airflow system is that the tuning is done by the mass
airflow sensor. Theese appeared on 1989 and newer ford cars with sequential
injection replacing bank firing the injectors in 1993. I am doing a four
rotor which has an airflow equivalent of a 5.2 liter piston engine. I have
selected the 80MM MAF sensor from a 5.0 mustang and a 1994 EEC-IV computer
with the separate EDIS ignition parts. I got everything for $85 on E-bay
including plug wires and an aftermarket trigger wheel. This setup uses 19
pound injectors which I need 8 of  (two per rotor). If you are doing a 3
rotor a setup from a ford 3.8liter would be about right. The important thing
is that the mass air flow meter, the injectors, and the EEC-IV all have to
be a set for the onboard calibration to be correct.Also the number of
cylinders the EDIS (electronic distributor)  generates controls the number
of injector pulses as it is also an input to the EEC-IV computer. If you
have a two rotor the 2.3 liter could be used however it would have to be
recalibrated  to use a MAF sensor from the 3.8 liter engine because the MAF
would exceed the 4.7 volt limit the EEC-IV accepts for full flow since a two
rotor needs more than 2.6 liter parts and another 15% if it is a P-port. I
also bought some 5.8 liter parts for my four rotor since 5.0 seems marginal
on airflow. There is an operating limit on the EDIS4 ignition module that
occurs at 8000 RPM due to the dwell of the ignition signals running together
just after that point causing misfire. These systems determine the actual
amount of air into the engine and adjust for temperature, humidity, and
barometric pressure, and then add the appropriate fuel reguardless what
altitude or temp the engine is operating at which is my goal. Ultimately
being able to lean out at higher altitude cruise will be required for fuel
savings, however having reliable parts off the shelf from an autoparts store
meets my current plans. It has taken a lot of time to design the airframe
and engine and I see no need to build tires, roller bearings and electrical
parts when well made components are readily available. There are thousands
of internet sites available on this injection and ignition, and several
detailed books being sold. I looked at Honda, Nissan, and GM systems most of
which can be reflashed or chipped more easily than the Ford system, and I
had several GM pickups with fine working MAF systems. I couldn't easily find
pinout tables to wire these other systems and don't want speed density or
cam position sensor inputs which narowed the search to Ford systems. Mazda
also used MAF systems on  RX8 rotarys which could be used however the used
engines I bought came without ECU and often damages sensors. The high cost
of replacing these parts and general lack of information on their operation
was less than appealing.

george grimes