Misfires Module B

The original condition was a miss when running with B switch on only. After the connector swap, the miss was with A switch on only.  So, that means that originally B trigger coil and ignition switch was using the B ignition system and had a miss. After the connector swap, the same trigger coil and ignition switch ran fine. The miss was coming from the A trigger coil and switch. Effectively proving that the trigger coils and mag switches are good. The problem has to be further down the line. 

The next step is to swap the coils relative to the modules.

The easiest location to do this is at the vertical connectors.

it is tight in there but you can make a release tool out of a piece of music wire or a long thin sacrificial screwdriver by heating the metal with a propane torch until it is red hot.  

You can then easily bend the tip 90° to get it to reach the release tabs.

Thanks Bill.  I appreciate the tip and will try to get that done today. Tom

Hi Bill.  I put the horizontal plugs back where they belong.  Made your tool and it worked.  Swapped vertical connectors.   Roughness moved from B to A.
In studying the print, that says that the Ignition modules are good.  I have already changed the plugs, tested the spark plug caps for pull off grip, and ohms tested the plug wire pairs, which also verifies that the coil secondaries and plug wires are good.  So the problem must be between the ignition modules output to the coil primary.  Still not sure which one, but it is either the 3 & 4 top, or 1 & 2 bottom coil circuit.  So what to do next.....Tom

Good News!

I hope you are happy that you didn't spend that $1000 on a module that you would not have needed.  

It is also likely that the coils are also good and all that you have is a marginal coil terminal connection that is vibrating and intermittent.

According to the Maintenance Manual, the "B" coils are the one nearest cylinders #2 and #3.

Contrary to logic, Coil #2 fires cylinders 3 and 4 TOP and...

Coil #3 fires cylinders 1 and 2 BOTTOM.

At least that is what the drawing indicates. But it makes no difference because we only want to find the problem, and which plug is intermittent is only academic.

Check the Primary (Low Voltage) connections on coils #2 and #3.

The connectors should not be able to be even wiggled without some effort if they are secure.

If that gives no result, Swapping the two front coils would be my first choice as it might be easier and it is a 50/50 shot anyway.