How the 4A-GE ECU works

[Red]

Where have you folks been hiding.<G>

If anyone knows how or whether the original 85 ECUs were different from the later ones in the non-turbo 4AGEs, like my 85 GTS, I'd love to hear about it. Apparently the 86/87 models got higher EPA ratings and actual higher mileage in the US models--and none of us can find any differences to account for that, unless it is something subtle internal in the engine or the ECU. I was hoping ECU "improvement" might be possible, but since these engines have no knock sensor there are limits. I know there are some aftermarket ECUs for steep prices but with no turbo and no knock sensor, they're wasted on my stock car.<G>

A thought on why there are two boards joined by a ribbon cable: Back then, some of the Japanese electronics companies, including the big ones, sent work home to cottage workers. They might send home 100 people, each with six baskets of parts, and expect to get back 600 alternators the next morning for that famous "just in time" zero-inventory production. In a situation like that, for small parts runs, I could see separate circuit boards going home in the basket to be hand-soldered to the ribbon cable during ECU assembly. Odds are it was this or a similar mundane production reason.

Much of the electrical system (ignition and charging both) on these cars was semi-primitive for the time they were built, about 10-15 years behind many GM domestic products. Like using a cap and rotor, instead of a reluctor assembly, and an alternator with wide (loose) regulation. And using the same exact type of wire for both the alternator output, and battery voltage sense leads. Wasted on one, too thin on the other.