Re: Monitor Automotive Spark Plug?

In message <b7GdnT1B_esaR5DXnZ2dnUVZ_sqdnZ2d@xxxxxxxxxxxx>, eeboarder <jmeyer@xxxxxxxxxxxxxxxxxxxx> writes
the signal just a simple pulse?
No. It's got several distinctly different characteristics, you can tell an awful lot about the quality of the engine and ignition system with the spark signal.
What kind of current is there? Does the
current create the spark and then return through the same cable?

I just hooked a split core current transformer with 3000 windings around a
spark plug cable and got nothing. I'm trying to re-create a signal similar
to that which a timing light would use.

Then get a hold of a timing light clamp and see how it's done.

Get a hold of a clamp on EMI filter, wind ~ten turns of enamelled copper wire around one half of the ferrite and then attach a scope to the ends of the ECW, see what sort of signal you get out. I guarantee it's not a 'simple' pulse.

Really, I would like to just know when this engine is on and off without
any lag. I also don't want to shutdown the engine to install it.

Tap into the crank sensor, tap into the ignition coil LT drive signal or the injector drive (assuming it uses fuel injection).

I had success using hall effect sensors on fuel injector bodies and also on ignition coils, extremely easy to deal with and also logic compatible if you pick the right one although a simple comparator circuit worked best as it was adjustable to suit.

Plenty of ways to tell if an engine is running that are simpler to interface to and measure than a spark plug lead.

Any ideas or help would be much appreciated.

Clint Sharp