I'm used to working on my carbed 240s, but my sister's '89 245 is getting poor mileage so looking for reasons. No codes being set.

Anyhow, I noticed that the injectors (other than the cold start) are all wired to fire at the same time. When one is opening for the intake stroke, the others are opening on the compression, power, and exhaust strokes. That is, 3 out of 4 injectors are opening at the wrong time because they are all wired together.

The injectors, since they are placed by the intake valves are supposed to be firing individually on the intake stroke. Yet, the ECU isn't wired to do it individually, or may not even be designed to do that. Why?

Furthermore, the ECU can't compensate for a non-firing injector because fuel from other injectors can't really reach it, because the design of the intake manifold isolates the injectors. Wouldn't it have been better if the injectors had been placed in the common area just after the throttle body, so the ECU could better adjust for fuel mix reaching the cylinders? Maybe even doing away with a couple of injectors?

So what am I misunderstanding?
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1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.