It says to keep the same injectors and resistors, so I'm confused on that.
It's an issue of resistance through each injector circuit. Resistance is a measure of how much a given circuit or component impedes the flow of electrical current (amperage). The higher the resistance, the less current can get through.
OBD-0 injectors are peak-hold type injectors. They're designed to be snapped open by a quick surge of current, then held there by a smaller amount. As such, they have a less powerful coil (the electromagnet that opens the injector valve) and a lower resistance which allows for that initial surge of power.
OBD-1 injectors are saturated type injectors. They're designed to be opened and held open by a constant level of electrical current. As such, they have a more powerful coil and higher resistance.
Honda ECUs are all designed to drive saturated type injectors. That is, the ECU only switches power on or off, there's no control over the current flow.
If you simply plugged an OBD-0 peak-hold injector into an OBD-1 setup, it's lower resistance would allow much more electrical current to flow through the ECU than it's designed for. Enough so to damage the ECU's injector drivers or overheat the injector coils. OBD-0 setups get around this problem by putting an additional resistor in the circuit of each injector which limits current flow, protecting the ECU.
If you put an OBD-1 saturated injector into an OBD-0 setup, the injector's higher resistance would already be limiting it's current flow to a safe level, but the OBD-0 resistor box would take the limiting a step further, causing the injector to open sluggishly or not at all.
The solution here is fairly simple: If you're using OBD-0 injectors, use the resistor box along with them. If you're using OBD-1 injectors, install jumpers where the resistor box would be. OBD-1 engine harnesses already have a jumper in place - if you look at the driver's shock tower connectors, you'll see one with a plug in it. That plug is just a bunch of jumpers which distribute power to the injectors and other 12v components on the engine.
I'm guessing I will be needing an OBD1 dizzy as well. [...] Does it have to come from an EX/Si? Can I use my stock OBD0 dizzy with a conversion harness?
I think the VX uses the same distributor as the EX/Si if you're really after one. I've run my 'Z6 on a P06 ECU (normally coupled with the D15B7) before without issues. That says to me that all the OBD-1 Civic distributors use the same sensor pulse patterns, making them electricly compatable.
As for OBD-0 distributors, the sensor pulse patterns are different from OBD-1... The ECU won't be able to run the engine properly.
I heard someone talking about the O2 sensor in a VX civic being something special, what is that?
The VX also uses a wideband as akirarex was saying. You need a special controller to make use of the wideband sensor - it won't work if you just hook it up to a P28. The VX ECU will obviously run it, but that ECU is a completely different animal than the P28. I don't think anyone has disassembled the VX code (though it has
been a while since i looked at pgmfi.org) and tried to do anything with it, so it's basicly unchippable.