Carburettors versus electronic fuel injection (EFI); automotive fans above a certain age will be well versed in the differences. While early EFI systems had their failings, the technology brought with it a new standard of reliability and control. By the early 1990s, the vast majority of vehicles were sold with EFI, and carburettors became a thing of the past.
The Mazda Miata was no exception. Shipping in 1989, it featured not only multiport fuel injection, but also a distributorless ignition system. Consisting of two coilpacks in a wasted spark configuration, with computer-controlled timing, the system was quite advanced for its time, especially for a budget sports car.
Despite the Miata’s technological credentials, those in the modified car scene tend to go their own way. A man by the name of Evan happened to be one such individual and decided to do just this — scrapping the EFI system and going with a retro carburetor setup. It was around this point that this I got involved, and mechanical tinkering ensued.
Continue reading “Putting Carbs On A Miata, Because It’s Awesome”
Carburettors were king for decades, until the onward march of technology brought electronic fuel injection to the fore. During their final years, a handful of automakers experimented with computer control of the humble carb, trying to squeeze out every last bit of efficiency and reduce pollution as much as possible. [NeXT] happened to own a vehicle fitted with AMC’s Computerized Engine Control system, and decided to see what made it tick.
This was easier said than done due to choices made by Ford, who manufactured the engine computer for AMC. Unlike modern ECUs which usually feature a metal case fitted with rubber gaskets, the CEC computer was potted in epoxy. [NeXT] was able to de-pot the circuit board by placing it in a stock pot of boiling water, and then slowly peeling the epoxy away.
With the potting removed, it was possible to begin reverse engineering the board. The main microcontroller is an Intel 8049, of the MCS-48 family. The board uses through-hole technology, and only features a handful of other small ICs.
It’s always interesting to look back at forgotten technologies and see how things were done in decades past. [NeXT] hopes to keep working on the project, intending to dump the ROM from the CEC module and build a replacement computer with an Arduino. It’s possible to build your own ECU from scratch, so we’re looking forward to seeing [NeXT]’s AMC Eagle running on modern silicon real soon.