That may be a result of low spec, "being years behind" (top European production) or designing for cost economy in mass production. I have noticed that one thin

That may be a result of low spec, "being years behind" (top European production) or designing for cost economy in mass production. I have noticed that one thing Delco does is to commission custom silicon with a view to saving money as millions of units are manufactured. Since additional complexity has the potential to reduce yield, why not shave bits off an ADC if the precision isn't needed? On a low spec engine, like the TBI 350cid, probably almost all of the inputs can be approximations, so the level of precision and accuracy you'd expect from buying an industrial sensor and off the shelf, discrete ADC is not necessary. And it follows that the sensors themselves should be as cheap as possible as far as it lets the engine meet the mandated goals, including a certain degree of reliability. Of course, I hope that a modern design of DOHC engine facing modern emissions regulations will be fitted with more advanced sensors and controls. The serial data link for the electronic carburetor control abomination and EFI controls is an example of the thoughtfulness that I meant. They implemented it really early, even quite earlier than the German makes I know about. It was undoubtedly priceless to have at the factory (for those cases where the factory cared - thinking on the shop floor seemed to have been a decade behind management) and would have been eminently useful in the dealership service bay if the techs had decided to make use of it.