Greetings,

I've been playing around with both ECU and TCU (DSG) tuning on the MED9.1 and CXX DSG platform and I would like to share a few things and also see if what I want to do is attainable.

From what I can find, the TCU uses Momentreduktion to protect the gearbox and avoid clutch slips during the shift transition between clutches, it is what gives the DSG their fart noise as well.  Of course it is necessary to prevent excessive clutch wear during the engagement phase, HOWEVER it can be very annoying when the TCU torque reduction command results in the ECU cutting boost / throttle / opening the N249 (DV) when shifting under peak boost/torque (+- 3500 rpm on stock turbo)

I have raised the torque limiters on the gearbox, but I can clearly hear and feel the DV opening on the shift.  Particulary if I shift 2 -> 3 under peak torque.

What I want to achieve is the application of Ignition-cut (Fast-Path) only Momentreduktion, as far as I understand, the TCU will send a desired torque value CAN signal to the ECU, the ECU will then determine how it is going to cut the torque (Ignition/N75/N249/Throttle).

What I can see on the TCU side is:

- MaximaleMomentReduktion(spelling) or Maximum Torque Reduction (Set to 400 nm stock), I assume this means it can cut up to (Current Torque - 400 nm).  Would reducing this to say 150 nm perhaps fool the ECU into thinking that an ignition-only cut will suffice?  Or will this result in a harder than normal shift/clutch slip during the transition?

- Maximum MomentReduktionDuration, would reducing this also affect the ECUs decision to use fast/slow path torque intervention by reducing the duration that torque reduction is active?  I have also decreased the shift times in Tiptronic, so would a lower torque reduction duration be appropriate as it's not needed for as long?

I just want to achieve the fastest, smoothest shifts even if it needs to drop Ignition to 30 ATDC to achieve it, as long as it isn't cutting boost.  I have lowered the minimum ignition timing during shift operation as well (mostly for the sound).

Any help would be appreciated I'm not looking to be spoonfed, I'm just looking for guidance from anyone who has also tried to achieve the same.  

I most certainly will, and when I resolve the issue I will update the thread as I've done on previous threads so that we may all benefit from glorious DSG shifts, but I was just hoping that someone could offer a shove in the right direction, i.e should I be looking at an Action change (TCU) or Reaction change (ECU).

Thank you for the response, by 'time for synchronisation' I assume you mean the Upshift/Gear change duration?  or do you mean the Duration of Torque reduction?

I have already reduced the minimum ignition angle and increased KFZWOP in the high load areas so that the torque calculation shows that the lower ignition angle has decreased the torque a lot (hopefully this is an effective way).

Very good information, having this same issue. Well explained, hopefully this will solve my dropping boost when shifting issue.

I can upload logs later today. Car shifts fine when cold and no boost drop. As soon as trans gets over 50c it likes to drop boost in random gears. As soon as it’s I continue driving it starts to do it in every gear and shifts are sloppy. This is my first time messing with dsg. There’s a big learning curve for me. I’m here to listen. Just tell me what data you need and I can provide.

When you’re talking about seeing through the CAN, do you mean watching the measuring block maf-sp? I’m messing with simos 8.5 just so you know. Yes in my logs I watch my maf setpoint drop to 800 when it was at 2300 before it shifted. Then I watch the rfp shoot sky high and my boost bleed away until next gear engagement.

Got it! Now at least I know what direction to go. I’ll keep reading the fr about shifting sp in the ecu. I didn’t have this problem until I went e40 and added a lot of timing. Will keep you guys updated. Thanks for the insight.

Yes, was a pain and multiple flashes. There’s a limiter that was stopping me. Also believe maf_sp and supercharger efficiency map had a lot to do with it.