Wasted Spark Ignition systems

[Spud72]

Hi, was wondering if you could clear something up for me.

I'm happy with how wasted spark works when the circuit is complete.

However, when it goes open circuit on one plug/lead is it true to say the the current WILL find its way back to the coil by any means possible. Even if that means "Tracking" from the Low tension side through the magnetic field and onto the HT side?

When I scoped the working plug/lead I saw what looked like pressure fluctuations in the coil, is this right?

Any help would be much appreciated.

 

[Skogsgurra]

It depends. If you have a system whith two plugs/coil (very common) and open the cable on one of the plugs then the other plug will work and take all of the energy that usually is divided between the two. All that happens is that you get more punch in the remaining plug.

If you only have one plug connected and remove the cable - I guess that your description is as good as anyone else's. The energy has to be wasyed somewhere, usually where it finds it way to ground most easily.

 

[Comcokid]

Spud72. There is also a "Automotive electrical & sensor engineering" forum where you might get additional information to this question.

 

[buzzp]

The open plug may or may not find a current path back to the source. Its all about potential. If the circuit is open, you will need the potential to jump across any air gaps to conduct. The size of the gap it can jump is mostly voltage dependant (elevation and humidity affect this also). My guess is that most open circuits on spark plug wires in autos would not find a path for the current to flow, it would simply discharge on the next cylinder (plug connected).