My solution was to simply move the staging relay from the secondary power circuit to the primary power circuit, so it runs on the secondary at low power and all 6 at higher power (20B).  Problem solved.
This may not be a solution for every case, as my secondary injectors are not all that far from the ports.
 

Hi Al, I have the same injectors like you. How do you do the modification with the relay?
Yesterday my EM2 came alive for a first time :)
Buly