Launch control confusion

[skirkland1980]

Hi again. Running MS2 v3.0 on my 83 280ZX turbo. I want to setup launch control. I'm a bit confused about wiring it up. I see I have two options on input, high and low. Which one should I use? Also a little confused on pin input. I'm using D14 for spark with a single coil. I also have D15 and D16 wired for water injection and TCC lockup though I haven't wired them to the rest of the car. Also using fidle for the fan. Which pin would be best to use for launch control. I've also been thinking about using boost control possibly in the future. Thanks.

http://www.msextra.com/doc/ms2extra/MS2-Extra_Hardware.htm#launch

http://www.msextra.com/doc/ms2extra/MS2-Extra_Hardware.htm#ms2options

[BLOZ UP]

I had it hooked up in my Z31, and I have it in my S30 (same motor, VG30ET). I forgot to implement the

though! In my Z31, however, it was like this:
 
I used the going low circuit. I decided to use this since the clutch switch I had closed when the clutch was engaged (pedal pushed in). Other people have used the clutch switch at the bottom of the pedal's travel. I didn't see this as working optimally for anything other than launching. Since I wanted flat-shift as well, I chose to implement this method.
 
However, in my case the Z31 has a normally open clutch switch installed (for cruise control, I believe), I replaced it with a normally closed one (from the brake pedal, to trigger the brake lights). I wanted the launch control to be activated as soon as the clutch was pressed in.
 
So, since the switch closes when you press the pedal, the going low circuit switches the pin on MS2. JS11 is what I used, but you can use several, IIRC. You just have to check against that chart to make sure you don't rule yourself out of using other features in the future. JS10 looks good in your case. I implemented all of this in the proto area, and brought out a single wire from the case to the clutch switch. I attached the other end of the clutch switch to the ground.
 
Once you do that, let the fun begin. I'll admit, I mainly did it for the flames to which I so far have been unable to produce. Keep in mind it causes really high EGTs and can burn up turbos and will definitely burn up catalytic converters. Edited February 21, 2013 by BLOZ UP

[skirkland1980]

Well I went ahead and did the mod. It was a lot easier than I thought it would be. I also used the low input since it was simpler. I'm running an automatic tranny so it used a button to mount on the dash, I was going to use JS10 but I guess I had used it before for something else and I couldn't get the solder out of the hole. So instead I used JS4. Are you able to build boost with it?

[BLOZ UP]

You have to "tune" it right. I can build 5psi or so with it. But I have the RPM limited to 3k or something a little low.

[skirkland1980]

Ok. How is yours tuned? I'm only making about 2 psi. Could it be my large .82ar turbine housing? All other internals are stock.

[letitsnow]

I can make full boost with mine, try using spark cut and forcing the timing to 0 or something ATDC and cut 3 of 5, maybe try going to 3500rpm. Fuel cut only makes a couple psi for me.

[Xnke]

You should know that using launch control will destroy those 50$ wideband O2 sensors in a major hurry. Gets expensive when you forget to take it out of the pipe!

 

Retard timing to 3 degrees at 2600, spark cut at 3200, cut 3 of 5. Snaps footlong flames out of the back of a straight-piped turbo ZX with a .63 housing.

[BLOZ UP]

Oh yes, fuel cut won't build much of anything. It will just act like a rev limiter. It will also be way gentler on your O2 sensor(s) and cats, if any.

 

For maximum flammage, 0 degrees or less timing BTDC, spark cut, and the highest RPM you want to launch at.

[skirkland1980]

Thanks for the info guys. My torque converter will not allow more than 2000 rpm during launch. I have retard set at 0 degrees at 1300 rpm and spark cut set to 1800 rpm. I'm still not getting much boost at launch, about 1psi, the same as when not using the launch control. I'd like to be realistic and get 5psi. Any other ideas? Thanks

[BLOZ UP]

That RPM is kind of low, but try cutting fewer sparks.

[skirkland1980]

Hi. I'm using a ms2 v3.57 now. I want to set up my launch control with my new MS. Is there any difference with ecu inputs or anything else? Thanks.

[BLOZ UP]

I'm not familiar with the SMD version. I know there are a few differences, but the daughter board is the same, so the inputs are unless something on the SMD is also using them. Also, no proto area.

[Bernardd]

Imo your converter is too tight.  You need at least another 1000rpm to start with.  I've never found that retarding timing works very well with an automatic.  I used 32-36deg's timing, 13 ish or so afr's and the boost would come on hard.  I also put the car into second gear to give it a higher stall and then dropped in low as I launched.  I had full boost almost instantly.  I now have a holset he351 that reaches full boost about the same time my foot hits the floor.  I'm getting 1.6 second launches and running high 6's in the 1/8th at 20psi (low boost). The other thing you could do is go with a smaller exhaust which I've also tried on that turbo.  You'll get boost a lot earlier but you give up a lot on the top end.  That is with a bored stock turbine housing. An actual stage 3 turbine housing would probably boost almost as soon but you'd gain back some top end as well.  With your current setup ironed out you should be running in the tens or low eleven's with good tires.  It's unfortunate that L28 guys aren't drag racers as there's not much info to work with.  Keep us posted with how it goes.

[skirkland1980]

Well my goal is 7.50 for now. I've done quite a bit to the car since this post first started. I'm running a th350 with a 4000 stall converter. I fixed my parking brake and connected an electric vacuum pump to the booster. I can actually get it stall at 3000 rpm now and 5 psi while using the parking brake to help keep the tires from spinning. My car is slow to hit 5 psi but when it does, 25 psi comes within a second. I did figure out my new launch control problem, the relay was bad. I'm using the brake switch and a toggle switch to activate launch. So I have a relay to complete the circuit for launch but the relay was bad and now it's working. Hopefully racing this friday the 12th if it's not raining.