Launch control for Motronic

[prj]

I think what he's getting at, it what is the difference between holding 5,000rpm with your foot vs with this function? If I hold 5,000 rpm in my car there's pretty much zero boost so I assume something is different, 0.7bar is quite alot!

Exactly. 0.7 bar vs. -0.3 bar. 1 bar difference.
You can get a bit more by playing with the throttle, but not as much.

Plus, it's just easier to launch by holding it WOT.

[S2central.net]

@Ross - you will kak your pants when you try VLC... honestly... its nothing like a normal launch by holding revs at 4k or 5k as you have no boost built up. Holding at WOT with VLC allows the turbo to build plenty enough boost and you just dial in the amount of revs needed for some wheelspin as you take off like the proverbial scalded cat - settings will depend a bit on personal tastes, tyre sizes and wet/dry weather. Thats essentially why we made it variable though - launch control for all seasons

[prj]

Okay, so spent the better part of the evening soldering.
The good news is - it works in my car as well now
Now I just need to get something to record a decent video with...

Have not mounted the knob yet, but will mount it in the coin tray tomorrow, so I don't touch it accidentally when not needed.

[Rocco]

so the launch control could be variable ,and we can do it easily whem sitting on the car?

[prj]

so the launch control could be variable ,and we can do it easily whem sitting on the car?

Yes...
You can turn a knob and RPM change... I will show it as a video soon

[Rocco]

Yes...
You can turn a knob and RPM change... I will show it as a video soon

or directly in a week

[prj]

So, here's a video I made today at lunch time with my phone, showing the knob...

http://www.youtube.com/watch?v=nVK_lIAPfk4&hd=1

I obviously was not going WOT, so there was no boost being built in this video.

[Acidburn]

looking good, and can probably mod that knob for on the dash switches of a type 85, is it always on or is there either a switch if you don't want it on or can it be turned right down/off?

[prj]

If you want it off, just turn the knob all the way to the right.
And it'll be the normal revlimit. Or unplug the cable, and it'll be 5000 rpm launch.

[S2central.net]

Unplug it only when shutdown though... remember that analog input has memory / capacitance going on there. As prj says though - cranking it all the way to 11 makes the launch rpm limit same as normal rpm limit - go ahead and launch there if your drivetrain has the gumption for it - OUCH my clutch !

[prj]

I tried unplugging it today without any issues on a running car.
Car detected unplugging fine. Tried three times.
Though, it's always a better idea to do that when not running, so you don't short anything by accident.

Basically - listen to Paul

[mouse]

Another suggestion for the knob location - take out the cig lighter and put it there.. could even use the lighter knob for a totally stealth install.

[S2central.net]

That ciggy lighter idea could work - i'll be supplying a very generic panel mount pot that I am sure can be customised with all sorts of funky knobs as stealthy or blatent as you like.

ANother point of interest came out of last nights work on looking at changes from 3B to coilpacks and ABY ECU - the 3B ECU doesn't get a VSS signal and therefore has no way to determine if the car is stationary or not for launch control. This would be a problem as grafting all the VSS code and PCB mods to bring it on would be a huge undertaking.

If there is sufficient interest in VLC for 3B/RR then it would need some auxiliary button or switch to activate it manually - wired into the ECU somehow on an unused input. That and I'd need a local guinea pig to prove it all out with.

[gedu]

I'm going to mount plenty of switches into my UrS4, 1 knob wouldn't make any difference

If you want to know what switches, I have 2 switches for front seatbelts reel mechanism (I have 3-point belts coming over both shoulders) 1 switch for servotronic disabling, 1 switch for cutting vss signal for rear diff lock...

[bikerjim]

not really been following this thread much and it may have been said but as a suggestion would it be possible to use a headlight beam adj switch or a heated seat switch to do the same thing and keep it looking more stock? just a thought