I love rotaries, I'm not afraid to say it. I bought an RX8 with essentially zero car experience and learned my way through. So here's a tale of mystery issues and obscure parts.
The engine bays on these things are ridiculously tight, and getting to anything actually on the block(fuel injectors, valving, coils, grounds, oil injectors) takes removing just about everything.
The problem I was attempting to correct is a tendency to rich out above ~6200RPM(read: when it goes to the open-loop tables). Now most of the time you would immediately look at your tune to fix an issue like this, but the funny thing is that I'm running a stock ECU, with a stock enough engine that it should still be doing fine, so unless the ECU is failing that isn't my problem.
After spending many hours looking for vacuum leaks, seafoaming the engine, replacing coils, replacing and texting new coils, replacing spark plugs and wires, testing fuel injectors, replacing fuel injectors, replacing O2 sensors, swapping MAFs with known working ones, checking CPS outputs, watching data logs of fuel trims, and continuing to be stumped, I thought it might be an issue with the oil injectors injecting too much at high load(it smells like oil when it has oen of it's episodes).
Turns out that two of them tested bad once I stripped it down to the block(see above picture) and I found a used set on a forum and scooped them up cheap.
These injectors are partly digitally controlled, but also depend on a form of vacuum regulation as well, and they have check-valves in them which had failed on two of mine.
After replacing the two bad ones, testing the system as a whole and being satisfied with the results, I put the whole shebang back together. No luck. The hunt continues!
I hope this article wasn't too out of left field, just figured I'd share a glimpse into owning a rotary and trouble shooting parts that most people haven't even heard of, it really puts a new meaning to on your own.