How the 4A-GE ECU works

[Red]

JMR-
I never said the Denso ECU's were primitive. In contrast, I said the ignition systems in these cars (and that means everything from the battery to the spark plug) were SEMI-primitive.
In the 1985 US AE88 we have a distributor cap and rotor, both mechanical parts that need routine replacement. That is, literally, SEMI (half) PRIMITIVE. If it also had mechanical points, I would call it totally primitive, because points+cap+rotor were the way cars were built 30 years earlier.
But by 1980, the US car makers had largely stopped using this system in favor of an all solid-state system (i.e. reluctor caps and magnetic sensors) so there were no mechanical tuneup parts to replace in the distributor cap. Toyota was still the more robust 2/3 of the obsoleted system, so I call it SEMI-PRIMITIVE since it was already OBSOLETE.
Thank god they at least got rid of the points, the worst part of it. I can set points to better than 1/2 degree of dwell, with just a feeler guage, but I'm happier not to need them at all.<G>

On using home builders? I'm fairly certain that Denso did in fact use them, I know that the Japanese auto industry used them for assembling startes and alterantors and this was reported in US business magazines which detailed the radical new "Just in Time" zero inventory system that the Japanese car makers were using, when it was "new" to US industry in the 70's or 80's. In the 70's Toyota was still pretty much a joke in the US, in the 80's these were still called "riceburners" because they just weren't up to par with the market standards, i.e. Honda had a massive class action suit over rust problems because they still hadn't learned to provide galvanic protection to metals.

The usual process would be for a company like Denso to build each of the ECU black modules themselves--just the black module with SMD's inside it--in a high tech facility. An then, at 7AM when a cottage worker came in to deliver the last night's work, they would be given ten or twenty more baskets, each basket with two black modules, to circuit boards, one ribbon cable--all the component parts to make up an ECU module. That "gross" assembly work would be done manually by 20-50-100 workers as it was needed to fill the next days orders. Literally, pieceworkers who were given NO WORK if there were no orders, and more work if there were orders. SMD assembly can also be done by the same process--you just need workers with different tools, better eyes, and a more valuable skill set. SMD "kits" of that kind are commercially sold in the US for various projects.

I do not know for a fact if Denso handled the ECU assemblies this way, I do know that style of work, in that industry, was happening at that time. And the way the ECU's are laid out, makes them a good candidate for that time of work.

When you consider the even the Apollo moon lander modules were all HAND ASSEMBLED, and the International Space Station today is still being HAND ASSEMBLED, it can still be the right way to build high technology products.<G>

Again, I didn't call the ECU's themselves primitive. Although, I would certainly like to know if they could be improved (for a stock NA engine like mine) and I'd really really like to know if there are specific differences in the ECUs or the maps from 1985 to the later models.

There are performance differences (significant gas mileage increase) in the last two years that none of us have found an explanantion for, in the US. The tire size change can't account for it, and I don't think the combustion chamber design or heads changed internally.