Ok, first things first, just so you know, it is actually called an AEI, not an ECU (just so you know what I'm talking about)
So, if you are getting no spark there are a few thing you can check.
Firstly, check the TDC wire. Sits on the top edge of the gearbox above the flywheel (this picks up a signal from teeth on flywheel and tells AEI when to send a spark) You can pick up a new one of these for about a fiver (try www.gsfcarparts.com)
The other things to check are the relays and the wires going to and from the main wiring loom connector behind the passenger side headlight. Test the wires with a multimeter from the ignition barrell through to the engine bay.
Good luck
R5 GTT, February 2006