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Steve,
I have attached a couple of images of CAS and ignition control signal traces from my systems. The violet trace is the CAS signal and the yellow trace is the coil control signal. I have voltage dividers on the inputs so the top of the control trace is actually 5 V, not 1.4 V as shown on the scale.
The image with the label starting with 260 shows the coil control signal at RPM below (left side) and above (right side) the spark intensity transition. There would be no spark during the time that the control signal is constantly high on the left side. The signals on the right side are what appears to be normal intended behavior with a dwell time of 4-5 ms. The way that my GM coil modules work is if within 8 ms after the coil control signal going high, there is no signal going low, then the module internally removes power to the primary winding and generates a spark anyway. I suspect that this is to prevent constant power being dissipated in the module in the absence of a good control signal. In any case, the module will produce a good spark when this happens, but it will be retarded about 5 ms from when it would normally occur. This retardation is probably not significant at 150 RPM for starting but would be more significant at higher RPM. Sparks below the transition RPM were irregular (intermittent) but strong.
The image with the label starting with 273A shows another set of traces during the transition. In this case, the dwell times were very short below the transition (<0.3 ms, my setup only had a 0.1 ms resolution) and the sparks under these conditions were very weak or non existent. Above the transition when the dwell time was over 4 ms, the sparks were intense and consistent.
If your system produces good sparks during the test mode, then it is most likely that the wiring is correct and the voltages and coil modules are good. It is possible that the EC2 is not producing the correct coil control signals during starting. This could be from the CAS signal not being what it should be, or a problem with the EC2 itself. My CAS signals appear to be good. The work-around for me was to use a mode 8 timing setting of 10 degrees retarded (the maximum retard possible with mode 8). This setting produced consistent 2.8 ms dwell times below 1200 RPM which, though only about half of nominal, still gives strong enough sparks for starting. It is possible to set the timing with mode 8 while cranking the engine even if it is not running under its own power. Retarding the timing this way may help. Then again, it may not.
For what it is worth...
Steve Boese
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