system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: How did fuel injected engines work before we would have had computers to control them?

how did an engine without a carburetor exist as early as the 1950s when modern fuel injected engines can’t really function without being computer controlled? And why would we still use carburetors for so long after fuel injection already existed?
gpt
Modern fuel injection engines use the computer to fine-tune the fuel air mix, generally to maximize fuel efficiency but they have power curves built into them and all sorts of tweaks.

That's not necessary for fuel injection to work, though. It can just open the injector for a set period of a revolution and call it good.  Older injection models worked like that just fine, using analog sensors on the cam and crank shafts to monitor timing. Later versions could even take into account the throttle position with a simple relationship rather than an actual computer calculation.  Modern technology could do that as well, but they're not set up to.  You can't adjust the injection timing well that way, and it's just all around inferior to the modern EFI setups in terms of both power and efficiency.

As to continuing to use carburetors:  They're cheap, simple, and could dump a metric fuckton of fuel if you had a big motor you were trying to feed at WOT. early injection systems could be a bit quirky, and it could be problematic to get them to deliver the right amount of fuel across a wide RPM band, particularly in larger, thirstier engines.  You also got intake injection systems that served as a sort of in-between, with one or two injectors sitting where an older carburetor would to get good atomization, but without the complexity of an injector per cylinder setup.