Fired up the engine again this morning, and did the following tests:

 

1)    Triggered the pirimary injectors individually; all “clicked” as expected.

 

2)    The ‘cold start’ switch works fine, and never needs to be left on more than about 4-5 seconds (at temps close to 70 F).  I am pleased that the engine always starts promptly; even after being stalled due to an over-rich condition; it restarts and clears quickly.

 

3)    Staging is not happening; at rpm below 2000, runs fine on secondary injectors, not as good on both sets, rather poorly on primary only.  Something wrong on staging issue, and (maybe) with primary injectors.

 

4)    Running on the secondary injectors only, slowed the engine all the way down to 800 rpm; and quite smooth all the way down.

 

5)    No difference between controllers A and B at any condition tested.

 

6)    Wiring harness does not allow reversing the injector connectors, but does allow connecting the primary injectors to the secondary leads. Did this and left the secondary disconnected.  The behavior was similar to running on ‘primary only’ when connected normally; but, I concluded, not the same. When connected to the secondary leads I could get almost to smooth running at about 1750 with the mixture knob near full lean.  At the same throttle and mixture setting, connecting them to the primary leads resulted in some surging, and required a bit richer mixture to stop the surge and was then not as smooth as when connected to the secondary leads.  

 

I don’t know what to conclude from item 5), except that it may be true that high-flow injectors in the primary rail at the rotor housing do not allow smooth running at low MAP and rpm with this controller. I hesitate to draw any conclusion until the reasons for the loss of staging function are resolved, and whether or not this has any relation to the way it runs on the primary only.

 

Al