I know that on Hondas/Acuras, the injector ground wires at the ECU are generally the first few wires in the "A" plug. I think they are A1, A3, A5, and A7, but don't quote me on that.
I was out testing, and I really belive there is no single-point-injector as I thought. One part that most of all looks like one is not, cause engine runs well without connection.
It looks your K-10 Micra only has an electronically-controlled carburetor. http://www.answers.com/topic/nissan-micra
The K-11 clearly has a fuel injection since 1992.