DIYEFI.org Forum

Hey all,

Just been throwing an idea around in my head for a RWD FE3 conversion. The main problem is clearance against the firewall for the standard distributor.

Using the standard ECU and CAS part of the distributor, and 4 coils (coil on plug style even). Could you use the trigger from the ecu, and make a simple circuit to switch between the 4 coils (or even just two of them in a wasted spark setup)?

Surely that would be dead simple? Or am I completely misunderstanding the way the standard controls for an electronic distributor work?

Thanks in advance,
Aaron

It can be done, but it's not as simple as it sounds, not if you want good performance anyway. Just do what you said you were going to do, it's a temporary setup anyway, so don't worry :-)

Yeah I doubt I will try it this time.

Why is complex about it? Why bad for performance?

Well, for a start, you'll want to extend the dwell and that requires starting the pulse before the ecu tells you to. To do it nicely would require almost as much effort as writing a whole EMS firmware ;-)

A distributor is just a mechanical demultiplexer, theres no reason you cant demux the ignition output at the logic level and trigger multiple IGBTs. Like Fred mentioned though, there is no proper way to extend or have overlapping dwell periods.

The most you can hope for is to perfectly preserve the dwell/firing period from the original ecu. If there is some way your original ecu can be reflashed, the dwell timing could be adjusted that way.

Depending on your trigger configuration in the distributor itself, demultiplexing the ignition output could be done with a low end microcontroller or perhaps even a couple logic chips. Basically you need to decode the trigger configuration to provide virtual "windows" for which the events to pass.