Launch Control & You!
 

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:
http://www.dbmiata.com/miata/launch/RSW.jpg

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:
http://www.dbmiata.com/miata/launch/DSC00825.jpg

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:
http://www.dbmiata.com/miata/launch/SSPX0634.jpg


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).

Software configuration
This is the easiest part.
Step 1
Go into the 2step rev limiter wizard
http://www.dbmiata.com/miata/launch/setup1.jpg
Step 2
Choose which level of Hysteresis you want. I just set it to middle for now
http://www.dbmiata.com/miata/launch/setup2.jpg
Step 3
Go into the 2step options
http://www.dbmiata.com/miata/launch/setup3.jpg
Step 4
Change the input to switch 6 ground on.
http://www.dbmiata.com/miata/launch/setup4.jpg

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.

*UPDATE*
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.

The how-to is up. Anti lag and real world testing to come next friday.

Great write up.
I've been running the launch control at pro-solo start autocrosses for a while and it works great.
I have mine at level 0 (the softest cut) and I cut fuel and spark at the same rpm. My car is supercharged though so most likely different settings would work best with turboed ones, especially if one wants lots of prebuilt boost at the start line with a turbo.

Yowza, EGTs would be rocketing! Don't do this for more than a few seconds!

I don't want to know what my EGT's are, but holy crap the launch is incredible. I went to the local track this Friday and the car did amazing. As soon as you let the clutch out the car rockets....

Nice.

Did you have to play with the rev limit RPM in order to control wheelspin off the line?

I was going to, but I left my laptop at home by mistake. It actually connected really well with my drag radials (with a good burnout), but street tires = 100% useless. It just leaves two big strips of rubber on the road.

With 275 wide super sticky hoosiers and my relatively low power (compared to high hp turbos around here) I found that around 4500 rpm is the best launch. Anything higher and the the tires start spinning.

Just bumping this because I think I'm going to try it out.

Still holding up? I'm a total noob to the software, but you gave good instructions and pics, so I think can do it.

I got to get the car running first tho. I messed with some stuff last weekend and now the first cylinder is misfiring and I'm not sure why. I replaced the plugs and wires, nothing helped. Any ideas where I should look next?

I have no idea about your cylinder misfire, but the launch control is still working great. As an update though, I put a toggle switch in between the wire I ran from the clutch switch to the ecu. This way I can just turn launch control on when I need it, and it won't interrupt with quick shifting.

How did it interrupt? And from my understanding, you cut the clutch wire in two. So then did you just add another wire in, run it to the FI/C, and connect all 3 wires together?

Also, I think I might start my own thread in this section about the misfire. Anyone with experience with this tuning software should chime in. I bought the car with all this stuff done and I'm rather confused.

When I cut the wire at the clutch switch, I didn't bother hooking the original wire back up. It seemed to do nothing at all. So the current configuration is Brown & white wire on switch -> an on/off toggle switch -> ecu. Also this doesn't work on the FI/C. Has to be an EMS.

Ah damn, this whole time I thought you said FI/C. Great write up anyways.

Nice writeup!

+1


Stupid question, so when you launch like this, do you feather the clutch some, or drop it and let the tires spin?

I completely drop it, that way I get the exact launch every time. At about 200HP at the wheel with 205 old drag radials, I was able to hook up and it was awesome. Street tires are useless but you leave a sweet strip.

This is what typically kills Torsens, right?
Or is it wheel hop?

I wouldn't doubt that this type of thing would shorten the life of any differential. It is a vicious amount of power going to the rear wheels. It's at 4500 RPM and 4psi of boost. If the tires break loose then no big deal, but if they hook up it will be a lot of stress. But I did this all last racing season and everything still feels great.

Here's an in-cabin video from drag racing last summer. It drags on a bit but I use the launch control to heat up my tires and also launching during the race.

Just a quick question: Is it normal for the AFR gauge to read lean while launching? I'm just testing it now, and this is happening.

I'm also doing it at levels where no boost is being built-- to make sure everything is okay-- if that makes a difference.

I suppose it all depends on your fuel table but I would suspect if you don't have it set up to make boost then it probably would run lean.