On SEFI systems, the camshaft position sensor gives the computer a one time signal when the engine is cranked to start the injection sequence. Until the engine is shut down again, it's a matter of programming to keep the injectors pulsing at the correct time, just like ignition. The original GM computers in the 1970's operated at a glacially slow 10 hertz. In the 1980's, Chrysler raised the clock frequency to 90 hertz, which is still a snail's pace compared to cell phones, PC's and other modern devices. Putting a real fuel injection system on a stone age engine like a stovebolt is an interesting concept, but isn't it sort of "lipstick on a pig"? Throttle body injection is a poor substitute for the real thing, which is why the automakers abandoned it about 40 years ago.
Jerry
