Electronic Ignition

[junkuser]

Have been involved in building a 6 litre class hydroplane to which we have fitted a Microtech engine management system.  Modified Ford V8.
Neither the owner nor myself have any knowledge of electronic ignition systems so had a an expert start the engine and do the basic settings.  Started straight off but later we discovered it had not been running on 1 and 6 which are fed by the same twin coil.(wasted spark system).  
We established that the problem was no signal getting to that coil pack so the black box that feeds the coils was taken back to the agent who said we had fried the box by turning the engine over without the HT leads connected to earthed spark plugs.  (There was no warning not to do this)
He said this causes a high voltage to go back to the unit.
Not sure if he meant a high voltage is generated in the primary winding when the field of the secondary collapsed or the HT voltage went through the insulation between the windings as I was not there.  (No evidence of external arcing at the time). The coil still seemed to behave normally when connected to another outlet from the box.

Does anyone have knowledge of Microtech or is this a problem common to other electronic ignition systems?

Seems a poor design as damage could occur if an HT lead fell off or someone removed one looking for a miss.

Feedback from anyone who understands these thing would be appreciated.

[bodders1]

Most likely to be a high voltage induced in the primary winding as the field collapsed rather than arcing over (unless, of course, you were testing it under water).
I agree with you that (if this is the cause) it is poor design.  
It has been well known since the evolution of transistors in the '50s that a back-EMF can fry the driving transistor.  The standard solution for protecting the transistor  where it drives a coil is to include a diode in reverse polarity across the coil windings to short out the offending voltage spike.  I am astonished that a commercially available product does not include this straightforward (and very cheap) protection.

[junkuser]

Thank you Bodders.
Herding electrons is not my field but you are helping me understand.

[bodders1]

junkuser wrote:

Herding electrons is not my field.

It hasn't been my field either for the last 23 years, but some things I learned at college seemed to have sunk in :-)