LNF Cobalt: reduce/eliminate power lag after shifting

[califcarm]

I do not plan on using NLS for fear of breaking something if I don't pull it off well.

But I experience what is described and shown in this thread (post #2 specifically mentions it):
https://www.cobaltss.net/forums/drag...-my-ss-324934/

A delay or slower ramp of power back up after even a very quick shift. I can get a modest spin going at part throttle in 1st gear, quickly shift to 2nd gear, where the spin (for a moment) will almost continue without interruption, but then there is a moment of reduce power where it the tires stop spinning, power will then ramp back up, and then the tires will begin to spin again. Something is killing power in the tune and it seems this is evident even in the stock tune, but more pronounced on modified tunes. It is not just the 1/2 shift, but that is the easiest example and seems to have the most exaggerated effects.

And after reading this thread on tuning the Camaro, it seems they have something similar. Some possible success in improving by eliminating CFCO (same as our DFCO?), and also working with the ESC since it can affect power:
https://www.hptuners.com/forum/showt...ht=power+delay

We can't touch the ESC since it is in the BCM and we don't have access to that, but I did turn off ESC completely and it seemed to help a little, but then again that might be in my head (normally drive in competitive mode).

My tune started with a GMS1 tune, then modified most of the "average" tables in the guides from this site on the LNF, within modest limits of not being too extreme, just for reference.

I have played with many tables (including optimum spark thinking it might be the best one) but have not had much luck, so just checking in to see which parameters or tables other have used to help with this?


edit: I have seen the "knee" in the throttle position curve where throttle goes quickly to about 75-80% after a shift, but then takes another .6-.8 additional seconds to fully open. I know others have stated you cannot get rid of that (trq management table we do not have access to?). Not sure if that is what is causing it or not.

[cobaltssoverbooster]

CFCO is clutch fuel cut off...it shuts the fuel off temporarily when the clutch is depressed. It functions physically like defco but they are not the same.
from past posters i would look into trq demand request which is an optimum spark and optimum torque topic. Also look into pid controls as when they arent correct the ramp in can be slow. thats about all you get.
You should be looking for topics from Randy as well...cant remember his username off my head though. havent seen him in here in a while but he did autocross and complained about that as well and wrote about controlling those tables to help eliminate the issue.

[califcarm]

CFCO is clutch fuel cut off...it shuts the fuel off temporarily when the clutch is depressed. It functions physically like defco but they are not the same.
from past posters i would look into trq demand request which is an optimum spark and optimum torque topic. Also look into pid controls as when they arent correct the ramp in can be slow. thats about all you get.
You should be looking for topics from Randy as well...cant remember his username off my head though. havent seen him in here in a while but he did autocross and complained about that as well and wrote about controlling those tables to help eliminate the issue.

Thanks for the direction. I had reduced it some with optimum spark, but the "urgency" (high numbers) that helped with post shift performance made throttle modulation out of turns too lively for my taste. I suppose I could make a map for drag racing only that would work, and then have a road/street map separately. But would love to figure out how to get one that does all if possible. I will search out the threads and subjects you mention.

For PID boost control, I have mine more aggressive set by quite a bit than the GMS1, allowing a little overshoot in my logs to get boost back as quickly as possible. I have not tried it mechanically on the LNF, but other applications get rid of any BPV or BOV completely. I had good success with this on another 2L turbo platform. I now there are some arguments about possible negative side affects for turbo thrust bearing life (or not, depending on which camp you are in), but all agree that it helps with shift response since the system cannot dump pressure from the charge pipes between shifts when there is no valve to do so. Not sure if anyone has tried this with an LNF or not?

[califcarm]

Looks like a mechanical solution helped some indicating that the ECM is probably using at least some boost control to cushion power return after shifting:

https://www.cobaltss.net/forums/2-0l...esults-192224/

I think the TPS still plays a factor also, but does not seem to be all of it.

And the ignition timing seems to come back instantly after shifting, so I don't think that is being used.

Just air flow control I guess.

They did not remove the BPV completely and can't find anyone that has on the LNF, but at least removing the solenoid stops the ECM from using that as dampening.

[cobaltssoverbooster]

i dont recall bpv maps but there are a few bpv settings that you might be able to adjust to prevent a complete bleed of the pressure. im super busy this week getting ready for the last drag race of the season at one of our local tracks. i dont have access at the moment to sift through the files and check what kind of bpv control lies within.