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Old 11-28-2020, 07:26 PM   #12
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Join Date: Aug 2014
Location: Boulder CO

I thought about this a bit more, and looked at some old notes, but I can't come up with any simple reason why the wasted spark board could damage the EZK.

The Miata ignitor will draw a little extra power, say ~15mA, from the EZK +5volt regulator, but this should be OK.

The wasted spark wire to the EZK VR circuit goes to the open collector output of a comparator chip. If it accidentally shorted to ground, for instance if it touched the metalized and grounded EZK case, it would temporarily cause a problem (no VR signal) but wouldn't be permanent.

The wasted spark wire to the EZK resistor is the same as the original EZK spark output pin (pin 16). It should already be protected against common faults.

When the EZK failed, did you try to pull diag codes? Did it respond at all, i.e. did you get a 1-1-1 blink code or nothing? (Note, the diag LED will always light up while the button is pushed, even if the probe wire is unconnected from ECU or EZK holes.)

Did you ever have either the old or the new coil powered up but with its spark plug cables or distributor cable removed? I'm wondering if a high voltage spark could have gotten into the EZK box through the new wasted spark ignitor wires, but that would most likely damage the wasted spark board itself.
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