I have spent most of my time disassembling the 2.7T ecu code, but not much timing playing with maps and tuning. I haven't yet modified any code in the ecu, but I do have the knowledge and ability to do so. Once the flashing and logging software I have written is more stable, I was planning on starting work on map switching and realtime map tuning. Working on supporting separate launch control maps would be a good project to do before I do full map switching support.

If you can tell me what maps you have been playing with so far for launch control, that would be a good starting point to make sure we are on the same page. On the "other" Audi forum I believe you mentioned you had tried this:

Set NMAX to your desired launch rpm
Set NMAXOG to your desired raised redline
Drop TMOTNMX to -48C
Set VNMX to your desired minimum vehicle speed for raised redline
Make sure TNMXH is set to 0

What were the problems you ran into doing it this way?

Do you just want a new ignition timing map to be referenced when the clutch is in, or would you want it to be different depending on the gear?

What about an ignition timing offset that is added/subtracted from the base ignition timing? This would be easy to do per gear for instance.

For flat shifting, would you want a map that dictates the RPM limit per gear while the clutch  is in?

So far I assume you only want to change the RPM limiter and the ignition timing depending on the current gear, and if the clutch is in.

Yes.


Mainly the car will sit there on the limiter, at say 4000rpm, controlling the launch point. But what you don't get is any boost built because the ignition timing isn't retarded significantly and the spark being cut. A little bit of both and we'd have an antilag that would build some boost pressure so you could get out of the hole properly. I think we need to define some terms here too.

wheel speed threshold for alternate limiter = managing wheelspin and being able to get out of the hole consistently
antilag = keeping the turbine speed high by burning exhaust in the manifold rather than the cylinders

A little bit of both and you get a two-step launch control.


That is exactly what I think we need. It needs to happen on decreasing loads and overrun, and only when the car is being driven hard.

Check these links:

http://www.lancerregister.com/showthread.php?s=&threadid=147683&highlight=ecutek+anti+lag

http://tinywrex.x10hosting.com/online/index.php

http://www.rallycars.com/Cars/bangbang.html

The ecutek code can adjust how aggressive the antilag is. I'm assuming it does that by regulating the amount of air injested by the SAI (we don't have one, maybe retrofit something from a tiptronic car, or try and increase overlap and open the throttle slightly?), the amount of timing retard, and amount of injector on time requested. I'm assuming it writes in new maps for all three.

Then you simply pick the proper speed limit delta to get it working right. You want it to control wheelspin, not just create tire smoke. So if the car launches and hits the limiter immediately, increase the km/hr threshold. If the car launches and blows the tires away, decrease it.

read vehicle speed
if vehicle speed > speed threshold then

    no adjustment to real RPM

else

    adjust real RPM by RPM delta

pass control to rev limiter check (fuel cut)

Effectively rev limit = rev limit - LC RPM delta, the higher the LC RPM delta value the lower the actual rev limit becomes, the lower the LC RPM delta value the higher the rev limit becomes.

If you really wanted to get crazy, how about a PID loop to control the hysteresis of wheel speed. Maybe use the known wheel speed against rpm and gear to target an optimal slip angle? Heheh now I'm just dreaming...

The ME7 determines desired boost from desired load, so if you have low desired load you are going to have low desired boost.

Flat shifting really doesn't concern me as much as having some more decel fuel and a real hard limit between gears so the throttle isn't closing.

I want to:

a) build boost off the line (two step)

b) change how it fuels on decel? could probably play with this in existing maps (haven't gotten that far yet) I know Lemmiwinks would change decel load fueling, hmm. basically a mild antilag.

It wouldn't be very hard to do separate RPM limits per gear when the clutch is in.


There is a map that defines gear specific RPM limits, and another map that defines gear specific load limits. There are currently no maps for load limits or RPM limits for when the clutch is in that I am aware of at the moment.


If you trick the ME7 into requesting more boost when the car is at a low RPM, how would you actually generate the boost?

OK that's a great read. That's pretty much exactly how I'd like to implement it here, although based on pedal position for sure. That way it stays "driver desired" and not a function of Motronic's throttle control.

Although again, the ideal launch control would keep the throttle wide open and limit revs with spark and fuel cut... one of the problems now is since the throttle is closing to keep revs around 4000, when I launch the car it hesitates for a second as it goes from ~40-50% throttle to 100% once the feedback loop realizes it can allow it open.

There are PID maps for the NMAX engine speed group that I'll get for you in the morning... I've started to play around with these, but I know it's possible to get a true hard limit in the stock routines.

I've reduced the throttle closing from 40% to 60%, but I still have to find the right map to get what I really want. IE, like my old volvo had. WOT (cause it was a cable) with the fuel simply cutting every oher rotation. bambambambambambam.

More tomorrow when I can sit in my driveway on the limiter for a half hour.