Can I wire speed sensor direct to ecu for launch control feature

[OMG70]

Hi I have a s13 SR20det in my MGB roadster , I want to setup the nistune launch control but need the speed sensor to talk to the ecu . Is this possible ? I have done a little research and it seems the speed speed sensor sends signal to the cluster and the cluster sends signal to the ecu. Is there a way to wire it straight from the speed sensor to the ecu as I have a gps speedo and dont have a s13 cluster ? Thanks in advance if you can help.

[Matt]

Short answer is no, since you need to convert hall effect to pulse

You can use the 'switch' launch control option to enable/disable

[OMG70]

Hi Matt does this mean I need to press the switch when I want to disable the launch control during my launch?

[Matt]

Yes the switch setting is currently push on/push off. Idea is to connect to the clutch switch

I am planning on writing a FP firmware update for only on during press in the next month (will need a board reflash)

[OMG70]

I have successfully wired in my launch control button but as I dont have a factory dash cluster how can I wire in a light so I know my launch control is activated

Also As I dont have a speed sensor I have to press the button once to activate the LC and then again during the launch when I want to disable it , a push and hold option would be way better and easier to control

Thanks heaps

[Matt]

You could use a LED + resistor (about 333 ohm or nearby like 470 ohm) from the CEL output to 12V, or a light similar current to dash lamp if you wish

[OMG70]

Thanks Matt , can you please explain in more detail as I’m not 100% sure how to wire in the resister . And I can use a 12 led . Thanks

[OMG70]

You could use a LED + resistor (about 333 ohm or nearby like 470 ohm) from the CEL output to 12V, or a light similar current to dash lamp if you wish

Thanks Matt , can you please explain in more detail as I’m not 100% sure how to wire in the resister . And I can use a 12 led . Thanks

[Matt]

Find the pinout for your ECU. Locate the CEL (check engine light)/MIL output line and solder the resistor to this, and then the LED to that, then the other side to ground wire on the ECU

LEDs must be wired in the correct direction. More info:
http://blog.sparkfuneducation.com/what-is-an-led

[jj205mi]

looking into this myself tonight and in a very similar situation, i have an s14a and just had the ecu reprogrammed for the feature pack. tonight i tried to get the launch working, i have an aftermarket digital display fitted so no CEL yet, speed is taken from a sensor on the drive shaft. but i set it to switched input, set the rpm to 2000 and earthed the power steering line on the ecu, (got the warning light on the Nistune for power steering) but no limiter while earthed?

I am sure its something i'm doing that's causing it not to work but haven't figured it out yet.

[Matt]

So CEL is flashing, but no limiting?

Try setting
1. launch cut limit to say 1500rpm
2. ignition retard = 0 and the retard cut at 1800rpm and then
3. Trigger switch under 1000rpm (CEL flashes, if enabled)
4. Test rev cut
5. Increase rev cut 1500rpm if okay to 2000rpm
6. Check ignition cut over 1800rpm

[jj205mi]

So CEL is flashing, but no limiting?

Try setting
1. launch cut limit to say 1500rpm
2. ignition retard = 0 and the retard cut at 1800rpm and then
3. Trigger switch under 1000rpm (CEL flashes, if enabled)
4. Test rev cut
5. Increase rev cut 1500rpm if okay to 2000rpm
6. Check ignition cut over 1800rpm

I never had a CEL wired but I done so today, and it’s working perfect now. Thanks again.

[Matt]

Excellent!

[jj205mi]

Well somehow I’ve managed to completely break it this time, before to get it working I was earthing then cable just as a test, so today I decided to wire it in properly with a switch.

Not sure what’s happened but now when I earth the power steering line I get nothing, checking for the warning light on nistune nothing at all I’ve checked the wiring etc (purple with white tracer) it’s putting out 5v (4. and when I earth it does nothing.

Launch control still coming on when switched on using nistune but nothing using that input...,

Again I’m sure it’s something I’m doing but I can’t see what yet.

[Matt]

Check a few things

1. Power steering indicator comes on the 'consult view' window when the switch is pressed
2. You activate it under 1000rpm (flashing should start then)
3. Ensure that the 'switch' checkbox is ticked and 'flashing' checkbox ticked in the Feature control flags still