Old school is a great basis for the new one. The difference is there are sensors that feed voltages to a computer. The throttle body merely meters the airflow,while a sensor measures how much. Most years of the C-4 used a MAF, but 2 or 3 years computed the mass airflow; called a speed density system. I have a hollowed out MAF, complete with the wire pigtail, used for plumbing , only, to make my engine look more like a stock TPI car.
Other sensors listen or knocking sounds, check the throttle position measure the iar temperature, maniflod air pressure, oxygen content in the exhaust, and such. The ECM merely computes how much fuel the engine needs to respond to the conditions and the demand. It also adjust the spark timing, retarding it if it 'hears' knocking.
Hence, while the carbs were amazingly effective, they were also a compromise in many operating concitions. The ECM can attain perfection, within limits, and optimize economy and power output.
I have a faily wild camshaft, with plenty of overlap. The 406SBC idles with some lope, as a hot car should, and did, "back when". This idle is about 850 RPM, whereas, if carbed, it would likely idle well above 1000. The 'experts' who witnessed the development of my chip claimed the car would never idle and would certainly not pass CA smog. It did both.
The ECM and many chip hours by Gary Leonhardt made it so. Gary understands the "old school" stuff about timing, mixture, timing advance, etc. He has learned about ECMs and applied his 'old school' to the new. He made the car a docile street car, yet an absolute terror, upon demand. Gary owns a shop, three generations of Vettes and mods lots of ZRs for customers. He calls my Vette "a Beast"; faster than the ZRs unless they are highly modded.
I was darn luck to have him work on my car. The ECM has to be reprogrammed for a modified car, beyond certain parameters. I am not sure you exceed them, yet.
