mk3design Posted March 2 Report Share Posted March 2 Okay, so I need some help on a few things, I've played around within my comfort zone but need some outside help at this point I am trying to dial in launch control on my DCT R32 GTR. I have launch RPM set to 5500RPM with ign trim set to -20 & activation at 5300RPM. I am only building up ~6PSI of boost on launch. I've tried -15, -25, even -30 and they all produce the same results. I would like to build 15PSI at time of launch, I am not sure why it's stopping here. Secondly, since after swapping from manual to DCT I will hit MAP limit after almost every shift, we are cutting ign on shifts but boost still spikes after shifts. I tried lowering the target boost and then setting map limit to my old target and it seemed to help a bit for the first and sometimes second gear change but eventually we still hit MAP limit. I've attached the current map and a log of a launch and pull. Also, in this log it only shows map limit reached twice, but looking at the data it should have flagged it 4 times. LAUNCH - FEB 19.llg MAP - MAR 1.pclr Quote Link to comment Share on other sites More sharing options...
Electredge Posted March 2 Report Share Posted March 2 I don't know G4+ software nearly as well as all the new stuff but your only removing 20% of your timing, and you should turn on fuel trim... try adding 30% fuel. Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 3 Report Share Posted March 3 Yeah, agree with Electredge, change Ign retard mode to Degrees or degrees absolute, I generally prefer absolute. In absolute mode "-20deg" means its fixed at 20deg ATDC, the main ign table is ignored. In Degrees mode, -20deg means it will remove 20deg from whatever value is currently being commanded from the normal ignition calculation. I think you will also need to increase the exit decay rate which will make the "bangs" more regular and generate more energy. Start at 30%/20ms, try at 50 & 70 to see where it likes it. Quote Link to comment Share on other sites More sharing options...
mk3design Posted March 3 Author Report Share Posted March 3 Thanks guys. Just tore the car down today to upgrade brakes but will try hopefully next week. Any ideas on relieving the overboosting symptoms after shifting? Quote Link to comment Share on other sites More sharing options...
Electredge Posted March 3 Report Share Posted March 3 1 minute ago, mk3design said: Thanks guys. Just tore the car down today to upgrade brakes but will try hopefully next week. Any ideas on relieving the overboosting symptoms after shifting? post a log of it happening Quote Link to comment Share on other sites More sharing options...
mk3design Posted March 3 Author Report Share Posted March 3 9 minutes ago, Electredge said: post a log of it happening You can see it happen in the log I posted in the first post Quote Link to comment Share on other sites More sharing options...
Electredge Posted March 3 Report Share Posted March 3 4 minutes ago, mk3design said: You can see it happen in the log I posted in the first post I would lower your proportional and derivative.... I'm sure adam might have better starting points for a G4+ but I'd test it with .5 Prop and .15 Der Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 3 Report Share Posted March 3 5 hours ago, mk3design said: Any ideas on relieving the overboosting symptoms after shifting? That is most likely just part of life when you have a big turbo and a gearbox capable of fast shifts but with large ratio changes. The wastegate DC drops below 15% in all of those spikes so the wastegate should be fully open already, the boost control function cant do much further. In your 2-3rd shift for example your RPM drops from ~8200 to 5000 in 0.1s, that means the engine is suddenly inhaling about 40% less air, however the turbo at say ~100kRPM has significant inertia so will take time to reduce its airflow by 40% to match what the engine is taking. A couple of thoughts to explore: Try to reduce exhaust energy - With such retarded ignition you are pumping a lot of the combustion heat into the turbine, you may be able to lower boost and run more optimised timing while still achieving the same power. Try fuel cut instead of ign, add a fuel trim during the shift to reduce EGT. Perhaps the wastegate flow priority can be improved. Possibly a solenoid controlled BOV or other similar bleed on the intake side can be be used to dump some pressure out during a shift. Quote Link to comment Share on other sites More sharing options...
mk3design Posted March 3 Author Report Share Posted March 3 Appreciate the response, super helpful! Speaking of your intake bleed suggestion, I just remembered that the GCU has a “DBW mod” that can modify the PPS on shifts too, something I imagine could help bleed intake pressure if set up correctly. If that doesn’t get me all the way there maybe a combo with your suggestions will do it. Quote Link to comment Share on other sites More sharing options...
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