If you are looking to find out how to setup launch control on your miata then this is the place. First off, let me say it is really easy. You just need some wires, a crimp connector, an extra pin to plug into your ECU socket (the EMS includes a bunch of spares), and about an hour or less. I'm going to structure this thread in how I tackled the whole thing.
SO I started off by doing the basic internet search for AEM EMS launch control, and found out it's about a 3 minute process using the 2 step rev limiter. Sadly, the instructions shown for this require the vehicle to have a vehicle speed sensor (VSS), and from my understanding, only the automatic 1990-93 miata's had accommodation for this [94 and newer can ignore this because they do have it]. Of course, I did some research, and some fellows on m.net said that the VSS is taken from the gauge cluster, and that you just needed to take the gauge out, run a line from the back of the cluster labeled RSW, and everything would be good to go. Not only would I have sweet launch control, but also a VSS signal feeding the ECU for different boost control options, etc. Here is the picture that illustrated this:
DO NOT DO THIS, the cake is a lie! You are wasting your valuable time by trying to connect that line. I tried, and noticed when I removed my gauge cluster that there was tape covering both holes:
I took the tape off of the RSW port and noticed an empty cavity underneath it. I decided that maybe just maybe, hooking it up might do something. I was wrong. It did nothing. Here's my awesome waste of time:
Once again, do not believe what other people say about things they obviously don't know anything about.
The 2 step rev limiter in the AEM EMS does not solely rely on the VSS, but you can also use a grounded switch. I looked at the ECU pinout and noticed that Switch #3 is for the clutch switch, and after inspecting it (it's the one on the top of clutch with a black wire and brown + white wire going into it), I decided to try and use that. This also did not work. This confused me, because the switch is just making a ground (from what I can tell). Unless the stock ecu sends some sort of voltage to it, the AEM EMS definitely does not.
I was about to give up at this point and just install a stupid toggle switch for $10, but then decided to try again. Now here are the actual steps to getting launch control working (sorry for the story):
Step 1 - Unplug the connector that is plugged into the switch at the top of the clutch petal. It is easier to access if you remove the panel below the steering wheel.
Step 2 - Once it is unplugged, cut the brown&white wire somewhere in the middle (there will be electrical tape that you will need to unwrap).
Step 3 - Strip the end of the wire you just cut (the one going into the connector), and hook up a new length of wire to this (something to reach the ECU on the other side). You can solder, crimp, whatever.
Step 4 - Once you get to the ECU, you now need to put an ECU PIN on the end of the wire. Make sure the wire gauge is quite small, since it needs to get into the ECU plastic connector. I forgot about this and had to add another piece of wire to the end that was thinner.
Step 5 - Look in the AEM EMS manual and find your ECU pinout diagram. Unplug connector #1, and then insert the new ECU pin & wire into 1i on the connector. This is an used input labeled Switch #6.
Step 6 - Clean up the mess & profit.
That brown & white wire does go from the switch to connector number 1V, but strangely this does not work (or it did not for me). Running a new line from that switch to the ECU pin 1i does work. I don't know why. It is completely possible that you could just leave that entire wire intact, cut it at the ECU, and then move it to 1i. I already had the wire running from the gauge cluster to the ECU, so I just used that wire and decided to leave that stock one in place (but cut at the switch).
This is the easiest part.
Go into the 2step rev limiter wizard
Choose which level of Hysteresis you want. I just set it to middle for now
Go into the 2step options
Change the input to switch 6 ground on.
You then need to set your rev limiters. I haven't played around with these settings at all, but the settings I have listed there seem to work fine. I HAVE NOT launched the car yet. I just got inside from setting it up, and with the clutch not depressed the car revs freely, with it depressed it begins its misfire at 4500 rpm.
Set the fuel cut and Retard Rev to 4500, and the ignition cut to 4700. I also set the Hysteris to level 9. This makes about 4 psi of boost while it is revving. Should = awesome.
I'll be updating this thread with anti-lag turbo spool settings.