Fueling

If we do not know the characterization of the fuel injectors (original or aftermarket), how do we go up setting the base injector pw or the fuel trim?

Unfortunately there's no easy solution. On average we could expect that a modern injector might have a dead time in the region of perhaps 0.85-1.00 ms. You're as well to offset the dead time curve until you're in that range and tune the engine. You need to understand that if you do this, there are likely to be some inconsistencies in the compensations the ECU applies but your only other option is to have the injectors characterised (I haven't found anyone who does this for end users), or buy injectors where the data is available.

Just remember that years back this data didn't exist and some ECUs didn't even compensate for dead time and we could still tune the engine. It's just that the results were less consistent than what we can achieve now.

Okay, I understand. So its basically impossible to get characterization data for original injectors when, for example, fitting bmw m3 injectors into a 325i. We just have to keep a rough deadtime of around 1 ms and tune on from there.