Bill,

The way the EC2 treats the cold switch when the MAP is below the staging threshold is to act as if the MAP is above the staging threshold when pin 30 is grounded.  Grounding pin 30 causes the EC2 to double the injector pulse width only when the MAP is above the staging threshold.  I've never seen a delay while the EC2 decides what to do. 

Measurements on my EC2's indicate that the pulse widths for the primary and secondary injectors are always the same regardless of the secondary injector differential (mode 6) setting.  It appears that adjusting mode 2 defines a flow rate for the primary injectors and adjusting mode 6 defines an average flow rate for the combination of the primary and secondary injectors.     

As a result, grounding pin 30 and removing power to either the primary or secondary injectors with a MAP below the staging MAP will most likely cause a mixture change because the EC2 is now calculating the injector pulse width using the flow rate determined by mode 6 instead of the one determined by mode 2.  With matched primary and secondary injectors, the end result should be the same mixture change no matter which injectors are disabled.

By using my suggested tuning procedure, the flow rates defined in mode 2 and in mode 6 will not be the same even if using matched primary and secondary injectors (which is a good thing as discussed previously). 

It is my opinion that Jeff has accurately described the reason for the delay in achieving stable conditions after activating the secondary injectors.  It takes some time for the fuel to reach the intake ports depending on the location of the secondary injector relative to the intake port. It also takes some time to remove the fuel from the secondary injector intake runner after disabling the secondary injector.  I have seen this indication many times in flight when crossing the staging threshold. 

Increasing the MAP from below the staging threshold to above it results in a momentary leaning of the mixture as seen on the O2 sensor.  If operating at already lean conditions, the engine will momentarily stumble.

Decreasing the MAP from above the staging threshold to below it results in a momentary richer mixture as seen on the O2 sensor.  I've never seen the engine stumble when making the change in this direction.

The things you describe do not seem to me to be an indication of an EC2 malfunction requiring repair to it.

Rather than try to come up with a special socket to work with the BR10IEX spark plugs, I bored out the rotor housings slightly so a standard socket could be used.  As shown in the photo, I took a wheel lug nut that I found lying in the street (I'm cheap too), machined it to fit the spark plug hole thread region, and inserted a cutting edge into the side of it.  This allowed me to counterbore the rotor housing with a socket wrench turning the lug nut.

Steve Boese