Launch Control Bypass Switch not working
 

93 NA MSPNP2

I just finished setting up launch control/FFS. Was having fun with it, and decided to wire in a switch that the previous owner had controlling some old garbage interior lighting. I used the brown/white wire (1V) on the factory harness to send the signal the "launch" on the options plug. I just repurposed that switch i mentioned and put it in-line between the brown/white wire I tapped into and the options plug, but it doesn't seem to be doing anything. Tested the switch with a multi-meter and it's working properly. Did some googling and it looks like 1V is "Launch In MS3X -11" whereas some people used 1N (5Vref Main 26). The wire coming out of the clutch switch (the lower switch that is depressed when the clutch is out) is brown/white, so I thought brown/white (1V) at the harness was the clutch switch.

I am confused. You had launch control working, then you added a switch inline and now it's not working? So, is launch control working, or is the override switch not working? The lower switch, I'd call that the starter interlock one and it's not depressed with the clutch out.

I remember something about the upper clutch switch, the one that is not starter interlock, is wired through the neutral switch on NA's. I don't think the 1.6 uses it for anything other than cancelling cruise, so it's a neutral/clutch switch. Maybe you are trying in neutral and you were in gear before?

I thought the starter interlock was the upper one (the one you buy the bypass plate from FM for) and it's the one attached to the firewall. I'm using the lower one seen here
https://cimg5.ibsrv.net/gimg/www.mia...2ccc1e6986.png

My wiring is as seen below. I added the switch where I put the red line.

https://cimg2.ibsrv.net/gimg/www.mia...eca19c056f.png
Pretty sure I figured out the answer though. MSPNP2 has a jumper "Launch via Clutch Switch" that basically negates the need for the options pin. That jumper is in place, so the car is just looking at the brown/white wire from the clutch. My switch isn't working because the ECU doesn't care about the options port. It's just looking at the brown/white wire that's in place. Now, if I wanted to use the options pin and use an external switch, I could use the switch to ground the black options launch pin without having anything to do with brown/white wire (and i would have to remove the "launch via clutch switch" jumper), but because the ECU needs to use the clutch switch for flat foot shifting, I just got rid of the switch and appropriately configured my vTPS requirement to activate launch control. I don't think i'll be using 80% throttle to rev match.....ever.

and here's what today's experimenting resulted in. Whoops.

4000 RPM hard limit
200 soft limit
"0" BTCD
Spark Cut

I started at "5" BTCD while i made sure everything else was working right. Kind of surprised the below happened when I switched to 0. It's not like I was retarding past TDC.


https://cimg3.ibsrv.net/gimg/www.mia...a9be9321f3.jpg
maybe because it's a generic no-name muffler? Do I need to avoid suitcase mufflers? Spark/Fuel cut?

You wanted dumbass pops and bangs and you got dumbass pops and bangs....

oh come on. I was out in the middle of nowhere on some country back road surrounded by cornfields dialing this in for the first time. Messing around with settings to see the differences. It's not like i was retarding the timing 15 degrees to make "flamez shoot out the back." I really didn't expect this to happen, but i guess that's what spark cut only can do. Spare me.

I would definitely switch to fuel cut, cause yeah, with the spark cut only, especially if you dont have a cat, (and even if you do), with spark cut only youre dumping a bunch of super fuel enriched air into the exhaust manifold, which means there are now explosive gasses inside your muffler, and while the above shouldnt happen with an OEM muffler, I would not recommend using only spark cut. If you have a turbo, using spark cut can blow up your turbo as the fuel enriched air can detonate inside your turbine housing. If you do have a cat, spark can can destroy it by dumping fuel into it. Leave spark cut for the dragsters with straightpipes. Use fuel cut.