In article
.com>,
"oilyspill" > wrote:

> If you were doing a cylinder balance test on a vehicle with DIS
> ignition, pulling one plug-wire would kill two cylinders?

You don't want to be pulling wires off if the engine is running.
The voltage is going to go somewhere, odds are, it will arc
across the coil winding causing damage or find it's way to the
ignition module causing damage.

> But, as long as you used a spark tester, the companion cylinder would
> still fire.

For these purposes of discussion, the coil doesn't care whether
the spark occurs inside the combustion chamber or outside of it.

> I guess you would have to kill the engine everytime you changed plug
> wires and restart. I wouldn't want to handle the wire with the engine
> running, I tried that before, that stuff has a bite to it. I was even
> holding an insulated screwdriver handle, still got me. I was dancing a
> jig hollering at the helper to turn the key off. The vehicle was OBD1.
> thanks

Much easier and safer to cut a piece of vacuum hose for each
cylinder, install the vacuum hose in between the plug wire and;
the plug or the coil tower (which ever is easier), start the
engine and short the spark at the piece of vacuum hose with a
grounding probe or a test light connected to ground.
of course, you want to disable the idle control and disconnect
the O2 sensor (force open loop) for accurate readings.

If you must poke, probe or mess around with the plug wires with
the engine running, connect a ground wire to the tool your using
so if the spark arcs to the tool, it will be shunted to ground
instead of zapping you.