VW with a misfire

[manx3094]

I have been using a Megajolt ignition on my air cooled VW for 10 years and been very happy with it.
It has developed a misfire that I’m having trouble diagnosing.
It’s a 1956cc with dual Dellorto 36mm carbs.
When I pull an ignition wire off cylinder 1 or 3 the idle speed makes a very slight change.
When I pull an ignition wire off cylinder 2 or 4 the engine dies.
Plug wires have been swapped around and the misfire does not follow the wires. In my opinion this shows the wires are good.
Any suggestions as to my next steps?

[brentp]

Try diagnosing it using a timing light to see if ignition is stable.

You can also run your ignition system with the Megajolt disconnected; it should be at a steady 10 degrees BTDC.

You can also check that your sensor bracket is secure, rigid and has not moved. Sometimes vibration at certain RPMs will cause the EDIS module to lose sync with the sensor; this can cause misfires as well.

We hope this helps; let us know what you find out.

[manx3094]

I was following the verification steps on the installation page.
It says to verify the PIP signal: Measure between EDIS pin 1 and ground. The result should be Approx. 12V when engine not running.
I only had 9.3 volts. The battery is fully charged. When I unplugged the MegaJolt I get 12.4 volts between pin 1 and ground.

Does this indicate a problem with my MegaJolt box?

[manx3094]

The sensor bracket is properly adjusted.