Just curious who gave you this information?
I know what engine this is. Came from Parker if I remember right. they did a bunch of work and noone actually knows why lol. Warranty blowout shop bill.. I dunno.
Back when they first started building the FiCHT engines, they were hand calibrating injectors. This was in 1997. As far as production market year.. Then they figured out they could get the same result by adding the capability in the software. By doing that they could achieve perfect results with alot less work. Yes the injectors themselves have changed over the years from the ficht, and the etec, however the concept remains the same. These injectors are A/C voltage driven with pulse modulation. They open and close based on the width, hertz, freq of the a/c voltage they are getting from the power supply within the EMM. these move ultrasonic fast. the New deisel stuff, BMW, and mercedez along with several other type are using similar technology now or the same tech. As a matter of fact Synerjet the manufacturer of the ETEC injector I believe manufactures all the deisel stuff. The Engine that you have has what was named a BIP injector. They switch in 08. Basically the same thing, however everytime this one opens it has to be told to close. Where as the previous voicecoil injectors all the wway back to the fichts were a little bit different on that. Some of it was mechanical and some was electronic. As far as how they close and reopen again.
The injector nozzles are so identically the same due to the machining that for there to be a huge difference by nozzle change would be extreemly rare. Its because whats actually important is the duration and length that the injector opens for. This is controlled electronically. The element inside the injector casing is the injector. Its the electronic coil, and the mechanical portion as well. Mechanical and electronic devices all have variances in being exactly perfect with one another. Its whats inside that casing That makes up 98 percent of how that injector gets controlled by that EMM. Piston or and mechanical part inside the cylinder block are only mechanical parts that are 97 percent identical. When we build Engine in ETEC land we bore cylinders based on exact size of a piston since again so manufactured part is identical. This is getting pretty fussy, however thats how we do it. Injector nozzle... meh. the length of the nozzles are all the same. Only thing that could be different is the machining of the flange inside where it opens. This nozzle gets open by the injector, and the injector needs to open the right length. in a perfect world yeah dont change nozzles, however it wont be a issue with lean condition as yes not programming a coeffecient file would be. Absolutely
As far as carbon build up goes, running at higher RPM will only produce more carbon in any engine. Why? because your burning more fuel. The more HP you pull from an engine the more fuel you burn. the more fuel you burn the more carbon. Since Etecs torque curve doesnt change a hell of alot between 4 and 55 theres absolutely no need to burn the extra fuel. Maybe if your in the bassmaster classic lol
Anyway moral of the story is that programming the injection on ETECs is extreemly important.