[shinysun]

Hello,

I usually have enjoyed 60 roll race, but recently I found some issues during drag race.

On 2-3 upshift, there are huge dip of spark advance as you can see the pic attached while no problems on 3-4, 4-5, 5-6

upshifts.

The engine tq source is "Trans S". I think the issue is dealing with it.
When I disable "upshift on Tq Reduction" in Tq management of TCM, the issue has almost gone, but it is quite risky.



any advice for it?

Thank you in advance.

[cjperformance]

To me it looks like a lot of wheel spin coupled with the rpms getting close to that 7k range where tq mgmt kicks in from the ECU due to the cutoff.

I can add more detail later on specific tables, but I'm replying on my phone at the moment.

Hard to tell from the log screenshot, but are you breaking the wheels loose on the 2-3?

[KingLT1]

Wheel spin combined with torque management. Look at your PID list...18.6 degrees of TM advance. Your Virtual Torque tables might need some work as well.

[shinysun]

Originally Posted by cjperformance

To me it looks like a lot of wheel spin coupled with the rpms getting close to that 7k range where tq mgmt kicks in from the ECU due to the cutoff.

I can add more detail later on specific tables, but I'm replying on my phone at the moment.

Hard to tell from the log screenshot, but are you breaking the wheels loose on the 2-3?

No, I am not. Thanks!

[shinysun]

Originally Posted by KingLT1

Wheel spin combined with torque management. Look at your PID list...18.6 degrees of TM advance. Your Virtual Torque tables might need some work as well.

Hm.. wheel spin. It's always pain in the ass.

About VTT, I matched it similar to the dyno number.
Could you advise about it more?

Thanks!

[KingLT1]

I would try about 5% over what the dyno reads. Make sure E85 tables are a little higher yet...7%.

[radz28]

Originally Posted by shinysun

Hm.. wheel spin. It's always pain in the ass.

About VTT, I matched it similar to the dyno number.
Could you advise about it more?

Thanks!

Originally Posted by KingLT1

I would try about 5% over what the dyno reads. Make sure E85 tables are a little higher yet...7%.

This.

If I recall - there are some statements that GM calibrators want about 5-10% accuracy for proper TQ control, especially for autos'.

I have to admit - some of the VTT strategies out there have been a little conflicting. One of the strategies I've seen, and tried, was when getting TMA at WOT (except for during shifting [A10s]) was to reduce VTT in the afflicted areas (SPARK/VVT/AIRMASS-MAP TABLE GROUPS/E' or not/etc-included). The logic for that was to LOWER reported TQ in those areas so the ECM wouldn't pull power. I'm not a tuner, but I'd rather keep the reported TQ (within reason) so SHIFTING PRESSURES/QUICKNESS keeps the clutches from slipping, because the TCM applies pressure based off of TQ, and I KNOW I'm making more power than stock, so I'm not trying to tell the ECM such. I found that incrementally increasing the VTT, in the correct areas, eventually kept TMA from coming in, so long as I balanced all other TQ-related channels.

I'm wouldn't know if this was the problem you're having, but the closer you have your VVE dialed in, the better your TQ modeling will be, and the less you fuss with the TQ model - the easier it will be. There are a few people that claim so. I took me a LONG time to balance everything after getting the VVE as dialed in as I could. I've touched DRIVER DEMAND, VIRTUAL TORQUE, and all of that, and it wasn't until my VVE/MAF were good that I could start balancing the rest, because DD influences FINAL THROTTLE TQ REQUEST, and PEAK TQ has to be above that, and MAX TQ has to be below FTTR, and PREDICTED/IMMEDIATE TQ has to be above ENGINE TQ, and you have to make sure your DD TQ all fall in line with those, and blah blah blah. And knowing when you fart around with some of those, you can also inflate the TQ your trying to work around, and it's all fun... lol... Again - it's said the closer your VVE is dialed-in, apparently, the better change all of the OEM TQ definitions could work. That isn't what I experienced, but I know I don't get TMA during WOT pulls (only at shifts), and my THROTTLE stays open. Nothing is max'd out either. I used dyno graphs and curves that were similar to my combination, extrapolated FLYWHEEL TQ, and added about 5% above that to my TQ model. It's not perfect, and I'm still working on PART THROTTLE, but I don't really get harsh shifts where I don't want them and the TRANNY doesn't run hot and seems happy. As my accelerator pedal moves toward the wood, the tranny reacts with better shifting.