How does the ECU send signals to the injectors in a 95 3VZ-E? Is it sequntial, one for each cylinder bank or "all at once"?

 

Sequential injection would be highly unusual on a 1995.
Look at the wiring diagram - I'm not that familiar with the V6, but I'll bet that it's wired as 2 banks.

Those two banks are likely fired in together if they are tied together with a common ground.

 

Ok, in the fsm it looks like its only one connecton out of the ECU to the injectors, so i guess they are fired together then, although thats a 93..

 

wiring diagrams I have say that all 6 injectors fire at the same time.

 

AFAIK, sequential didn't happen until ignition coils came 'round. I guess I'll have to do some digging and refresh my memory.