UPDATE to this update:
I decided to replace the 5AFE ecu with a 3SFE one.... now it works even better than even the 4AFE one.....
This is the ecu part number that I got: 89661-2D140... An A/T Caldina.
The only other change I did was to change the NSW pin. Originally, I tied this wire to the starter line so it has 12V only when you start using a manual ecu.... Its different for an A/T ecu... This has the effect of telling an A/T ecu that you are in gear and will give a higher idle speed than 750rpm, and maybe worse fuel mileage than before..... I then rewired the NSW pin and connected it to the Ignition ON wire on the ignition switch. Whenever you have the key in ON, it powers the NSW pin automatically.
This tells the ecu that the engine is in neutral and will lower the idle speed back to 750 rpm, and hopefully, better fuel mileage.
it now ides at 750 rpm, compensates for any load AND seems to have better fuel mileage than any other ecu I used so far.
But the best thing about this is the performance of having a 7AFE injector on my 5A block is realized with this ecu.... its just way better than any 7AFE or 4AFE or even the 5AFE ecu I used before.
I had to make an ecu adaptor to make it work since it is an automatic ecu (26-16-22) and my harness is for a manual (26-16-12).
The pins names are the same, its just the pin locations are different.
Also I used a 7AFE fuel injector (192 or 200cc/min) .... its a bit smaller than the 3SFE injector (213 cc/min) so the ecu can maximize the injector I am using now but they are close enough that the ecu may compensate for it.
When looking for a compatible ecu for your 4AFE engine, make sure that the ecu you want to use have the following pin names:
RSO, RSC - ISCV valve control
G1,G- cam sensor, I think.....
NE+, NE- crank sensor?
IGF, IGT power and tacho wires
VISC a/c idle up control
If the pin names include G1, G2, G, G-, NE, its for a different distributor, the one you want to use for your 4A would be the 4AGE silvertop/blacktop one. And ecus with this kind of dizzy would also have 4 injector wires for a sequential injection instead of batch fire like the 2nd gen 4AFE.
There may be 4AFE/7AFE ecus that may include G2, G- pin names instead of G1,G- pins. I have tested this (89661-1A280) and it does not work on my 4AFE distributor.
And then there are 7AFE ecus that have a totally different pins name and they may not include any NE or G pins at all.... These are the distributorless ecus and are to be used on the 7AFE lean burn engines.
Apparently these lean burn 7AFE have a different cylinder head design than non lean burn.... The most obvious one is that these engines have the injectors in the head and not on the intake manifold.
Now I still connect AC1 directly to the compressor coil to get lower idle.... can't be helped.... I think this is needed for proper operation.
What I now plan to do to the ACT pin is to connect it to the coil of a 12V SPDT relay (single pole, double throw) and connect the other end to the a/c amp power wire then connect the relay contacts to the a/c amp main power wire as well so that the ecu itself controls the a/c amp when accelerating hard.
When extra power is needed, the ecu will power the ACT pin (I hope), disconnecting the wires that power the a/c amp AND turns off the compressor automatically....
Each time you need extra acceleration, the ecu does this for extra power.