Cylinder ID sensor function?

[paperplane94]

I was doing some reading on the Cylinder ID sensor(the one attached to the spark plug wires) after I saw that the wires on mine had disconnected from the back of the plug(I am re-pinning it now). It left me very confused about its function.

First, I read that the CID sensor told the ecu to fire its injectors in semi-sequential patterns, potentially saving fuel and trimming the air/fuel ratio properly.

Then I read that it is not even necessary (my car was driving fine before this) because without the CID sensor the ecu defaults to batch mode which fires all the injectors at once.

THEN I read that all M20's don't even have a CID sensor input to the ecu. I read that the wires just go to the diagnostic connector and do nothing, therefore it was not necessary!!
But the Bentley for the e34 clearly states that pin #8 and #31 are for cylinder Identification.




SO WHAT THE HELL. I know its not necessary but does it have an ecu input AND if it does is it better to run in semi-sequential or batch mode???

EDIT:
BTW its a late model M20B25 1989 e34

[Sagaris]

ETA's fire all 6 at the same time, M20B25's fire 3 at a time.

[NC325iC]

i ran my m20 without one for a long time, to no known ill effect. Like you seem to have figured out (and theres no good way to confirm this) if the CID is unhooked the ecu supposedly defaults to fire all injectors each time, with the CID it will fire 3 and 3.
not sure if there are any noticeable benefits, of course some fuel savings will be present just based on firing fewer injectors in waste.