Info about widebands and tuning

[G-E]

Actually a great deal. While I can't speak for all the aftermarket codes, but, there's only one *given* to coordinate the injector pulse to, and that's the DRP (Distributor Refence Pulse). So as you move the timing, you're also changing when the injector opens.
not applicable

So as you advance the timing, you can expect the INDICATED AFR to change. Advancing the timing will indicate a leaner mixute, as well as retarding the timing, will indicate a richer mixture.

very true, and unrelated to above

Tuning is about gathering all the data you can, analysing it (correctly), and adjusting things accordingly. A WB is no more or less important then EGTs, and plug reading.

but egt can also lie, temperature readings are often significantly behind the curve, only steady state dyno tuning would give your sensors a good enough reference point for what's going on

[Grr]

cant say this pertains to the z31 ECM exactly as i havent seen the code, but it should and does in most cases. This guy is one of the best out there, so i respect his opinions on pretty much anything.
http://www.t6p.com/forums/showthread.php?t=8030
Gary