emjay
+1y
The conversion is possible to do. I have done it before but I had to build my own ECU. I used a megasquirt I setup with the narrow band o2 sensor, and it got the job done but was a PITA to tune. There is another member over on Mazdatruckin that does this swap as a hobby for all of his trucks.
The ECU can be wired into the stock harness but it you have to map out the correct wires. Also the car ECU is going to be tuned for a car and not a truck so it might not get you what you want.
You'll also need to get the valve cover and the distributor from the 626 if you plan to run the ECU for that vehicle. The valve cover is because the port is lower than the valve cover stock for the pickup, and there is a partition from the factory in place on the 626 VC. I used the stock pickup VC and I had to cut a notch in it and use JB weld to make a flat surface.
There is one more bracket that you are going to have to cut off of the stock intake manifold from the 626 because it will hit the thermostat housing of the B series otherwise. It's easy with a hack saw. And you'll need to make a partition for the coolant temp sensor because on the B series it's in the manifold and on the 626 it's on the head (could be the thermo housing, I don't remember.)