Ford EEC-IV Ignition Module

[Brian Warburton, c/o Turbo Systems Ltd]

>Hi! Could someone help me with a Ford EEC-IV TFI ignition module of a=20
>Ford Sierra (with HALL sensor and european ECU). I=B4ve built a control=20
>unit of a Siemens SAB80C517 microcontroller and now I have some=20
>difficulties in controlling the IM.
>
>I=B4ve come this far:
>
>output    -------         ------
>of              |         |
>HALL            |_________|
>               /          \
>              /      Start advance (say 12 deg BTDC)
>     "Max" advancd
>     (about 90 deg BTDC)
>
>"Start advance" is the point where EEC-IV fires when starting the engine.=
>=20
>Even if the ECU is disconnected the IM fires at "start advance" (limp=20
>home). The ECU tells to the IM when to fire with a rising edge. I tried=20
>that too. I switched the ignition signal OFF at "max advance" an ON when=20
>I wanted to fire, I could fire only AFTER "start advance". When I had an=20
>advance of about 30 deg the IM fired at "start advance".
>
>So, a few questions: Am I so far right?

>From the way you've described your TFI unit functionality, my guess
is that it's not a Ford TFI unit but a Ford EDIS unit. This takes
in the 36-1 signal from the VRS sensor (not HALL) and converts it
to a signal with 50% dutycycle and rising edges at 10 deg BTDC
for each cylinder which it feeds through to the EEC-iv. In return
the EEC-iv sends out a required spark advance signal every firing
event where the width of the pulse sent relates to the spark
advance required. The pulse timing from the ECU does NOT affect the
ignition timing. After a certain number of firing events without
receiving a valid advance pulse from the ECU, the EDIS switches to
it's default spark advance which is 10 deg BTDC. The EDIS unit of
course drives the standard Ford twin-coil pack (wasted spark). 


>Does ECU take care of dwell? With the falling edge? How to calculate that?
>

Dwell is handled automatically by the EDIS unit, but rate of
change of spark advance must be limited by the ECU to a few degrees
per firing event to avoid screwing it up.
 
>
>imonkare at bessel.tutech.fi
>