Cannot solve transient knock issue high RPM when letting of throttle (boosted)

[brosifSmith]

First some info, I'm tuning using Ecutek with RaceRom. I've got my maps pretty dialed in for my 2015 brz with the SBD turbo kit installed. I am targeting 6 psi of boost, my AFR's are on point.

I rarely have knock under load, and it pulls hard! everything seems well and good.. EXCEPT, I notice I always have what looks like transient knock after I do a pull, and when I begin to let off the throttle, but before I downshift.

so for instance, second gear pull, go from 2k rpm up to 6k rpm, throttle % falls to about 10 percent, load falls to .6 ish and the timing starts to climb because of the falling load, but then immediately I get Knock correction. sometimes -1 degree, sometimes -3 or -4 degrees. Those ones scare me, it's always when the load is pretty low like .6 and .7 but RPM is still high because I just let off throttle but have not downshifted. but I don't know if I should be concerned... Someone please advise, this is the opposite of tip in knock it seems...

Log so you can see what I'm talking about - https://datazap.me/u/brosifsmith/pur...zoom=3191-3359

this one is also very concerning. I've tried retarding transient a lot and seemingly no effect -
https://datazap.me/u/brosifsmith/pur...g=0&data=13-32

[brosifSmith]

Here's an example of one at higher RPM. Do I just nee to retard high RPM low load timing more? Shouldn't transient ignition retard be applying here? any ideas are greatly appreciated. I'm decently familiar with tuning at this point but this one is just annoying me now.

https://datazap.me/u/brosifsmith/pur...zoom=2012-2086

[DarkPira7e]

Have you tried swapping the knock sensor to see if there's consistency with a different one? Is the throttle gently falling to 10%, or are you only letting off part way?

Does this happen after a WOT pull?

[brosifSmith]

Originally Posted by DarkPira7e

Have you tried swapping the knock sensor to see if there's consistency with a different one? Is the throttle gently falling to 10%, or are you only letting off part way?

Does this happen after a WOT pull?

No to the knock sensor. Sometimes I let it off more aggressively but I usually let it off part way or slowly let off on it so I think that may be part of it, you can see in the log the AFR mixture is still rich and it's still injecting instead of going full lean like when you are coasting... and yes it'll happen after WOT as well.

[Kodename47]

Looks like Knock Correction doesn't really show FBKC but something else, looking at AK Knock and AK Fine these appear much more normal at lift off but it's regularly pulling timing on a WOT pull....

[brosifSmith]

Originally Posted by Kodename47

Looks like Knock Correction doesn't really show FBKC but something else, looking at AK Knock and AK Fine these appear much more normal at lift off but it's regularly pulling timing on a WOT pull....

true some of those WOT pulls i'll see a -1 in the fine learning knock correction, but I'm thinking a little too lean AFR for the timing I have. probably better to retard it a little more so I'm not right on that edge of MBT. and hey on that note, do you know the differences between when normal 'Knock Correction' happens compared to 'Ignition correction - AK Knock'? They seem to usually follow eachother pretty closely, but I have seen deviations. I always assumed they were referencing the same thing

[brosifSmith]

I'm sure none of you care but the issue was I needed to up transient knock retard pretty significantly at slightly higher load and very high RPM (.7 to .9 load and 5200 - 6500 rpm) which helped significantly. also lowered my base timing for the same range slightly. amen, case closed.