Just finished my BP swap.......what a journey!!!........I'm gonna throw in my two cents, and lots of thanks to Ryan and Dark_Rider2k3 for much needed info!
I used a combination of Typhoonk's BP swap journal from the 4cyl FAQ, and the "let's band to make a real BP guide" from the 4cyl Technical page. Both are very helpful but I still needed help from those who've already done a swap.
Anyway, I don't have many pics of the whole entire process, but I will share what I did take. Before I do that, let me just run down my setup. I bought a lot of parts and pieces but will only list the ones I used for the swap.PARTS
1994 Mazda Protege BP engine, 78k miles - $300 (local pick-up)
BP ECU and U-Code MAF (thanks to bogaut from clubprotege.com forums for that) - $50 (combined including S&H)
ECU Connector Pins (thanks to Ryan from mx-3 forums) - $postage stamp
Thermostat Gasket - $2 (Autozone)
5 liters 10W-30 Motor Oil - $18 (Autozone)
1 gallon Antifreeze - $13 (Autozone)
Champion Spark Plug Wire Set  - $13 (Rockauto)
4 NGK Spark Plugs  - $7 (Rockauto)
Throttle Body Gasket - $2 (Rockauto)
Bosch Oil Filter  - $5 (Rockauto)
Dayco AC/PS belt [4PVK1015] - $7 (Rockauto)
Mann Fuel Filter [MF1074] - $9 (Rockauto)
Walker Front Pipe Exhaust  - $104 (Amazon + 1 day shipping)
That was my list specifically for the swap. Only three months ago I had also purchased new motor mounts that from when I did my suspension that I swapped over to the new engine. I had also bought a new O2 sensor recently from when I did my exhaust last month, but I'm going to have to buy a new one because the threads got stripped when I removed it from the old exhaust manifold. Last spring I had put in a new thermostat and temperature sensor, those were also swapped over. I mention this because all these are parts that you should consider buying for an engine swap.ENGINE/TRANSMISSION
The BP engine was originally an automatic. My MX-3 is a manual with the F-series transmission. I'm ONLY doing the engine swap, not a transmission swap. Would I have gotten a G-series transmission, I would have needed new axles, axle seals, transmission oil, G-series flywheel and G-series clutch. (not claiming this is a complete parts list).
So the things you'll have to swap to a BP automatic engine from a B6 manual engine to work properly with the manual transmission are the throttle body and the flywheel (and of course the clutch).HARNESS
Just like various threads on here say, I was able to use the original B6 harness (the harness are the wires that connect from the computer to the various electrical plugs on the on the engine and transmission). Most of the connections are "Plug and Play" with a few exceptions (that being the fuel rail harness which I'll address in a minute). Just know that some of the positions of the connectors are not in the same exact postion on the BP engine as they are on the B6 engine. You're going to have to split the electrical tape and casing of the harness to get certain connections to plug in (ie, strand of ground wires from the O2 sensor/temp sensor wires bunch). I used the B6 fuel rail harness because the BP fuel rail harness conector is different. The B6 fuel rail harness has 6 pins on the connector and the BP fuel rail has 8 pins on the connector. (the 2 extra pins are supposed to be for the VICS sensor, more on that in a little bit). So the connectors from the BP/B6 fuel rail harness to the fuel injectors are the same. There is also a pea soup green colored connector that is also the same, although this is another connector where the location is different on the BP engine from the B6 engine, so you'll have to split the electrical tape and extend it to make it connect. There is a single ground wire that connects to the engine block, no problem. Now you have two connectors left on the BP harness that you're going to have to cut and splice, a brown connector and a similar style white connector.
The BROWN connector=Fuel Pressure Regulator sensor
The WHITE connector=VICS sensor
It's easy to forget which connector goes into which sensor because the connectors are exactly the same. But don't worry. The lines where the connectors are supposed to have either a dotted BROWN line or a dotted WHITE line, so just match the connector with the line.
The B6 fuel rail harness will now have only one connector left after you made the other connections. it's a plug which is for the fuel pressure regulator, but the connector is different on the BP engine. So cut off the plug and there are two colored wires, a red/white wire and and a green/orange wire. These will match up with the BROWN connector off the BP fuel rail, so splice it into the B6 fuel rail.
Now for the VICS.
There are many ways to go about connecting the VICS, some people like to remove the harness and add the wire onto the harness. I just ran it from the firewall separate from the harness, there's no right or wrong way to do this, just depends on how clean you want your car to look. I found out how to wire it up on the forums. Here's one link as an example: http://www.mx-3.com/phpBB3/viewtopic.php?f=3&t=77442ENGINE REMOVAL
Here is a pic of removing the engine underway. Battery, air intake and radiator out.
WHOLE ENGINE OUT!
YEAH, we had some beers!Some Snags
Not gonna go through the steps of engine removal, that info is all over the site. But I did have a few issues that needed addressing after the engine removal. I obviously swapped over the B6 alternator, AC compressor and power steering, but the belts on the BP engine pulleys are different. So I ended up removing the B6 pulleys and putting them on the BP. It's totally plug and play. Also, I have to make this note about the '94 Protege engine.
From what I understand the '90-'93 BP engines exhaust manifold will hook up with the B6 down pipe, no problem, straight plug and play. Also on these years engines, the O2 sensor is located on the exhaust manifold.
The '94 BP engine is like the bastard child of his generation engine. The exhaust manifold DOES NOT line up with the B6 down pipe, and also there is no O2 sensor hole on the exhaust manifold. That's why I needed to order the down pipe (specific for this year). The O2 sensor for this year engine is on the down pipe. The '94 Protege had two O2 sensors, pre and post catalytic converter. But since we're using the B6 harness, you'll only need the single wire O2 sensor. If you don't want to order the down pipe, the other option would be to get a '90-'93 BP exhaust manifold.
Also, before dropping in the BP, remove the pulleys, whether you intend to swap them from the B6 or not (if you leave the transmission in the car that is). Otherwise it's impossible to drop the engine in.BP SWAP
DONE! I'll soon post pics of the complete engine bay, and my suspension.