NefMoto

Just getting my head around PID variables. I'm curious in that all the IRL maps I've seen have an unreachable load request at low RPMs that would seem to be a factor in boost overshoot once actual nears request. Why would it not make sense to set lowest RPM load request values in IRL at closer to achievable targets in order to let PID do it's job with less tendency to overshoot?

Because everything you have said in this thread after the 1st half of the 2nd sentence is wrong.

Hahaha.

Well then - no answer, more reading!

KFMIRL is not a boost request map.

LDRXN is more or like what you could look at.
It limits RL.
And usualy it has low and therefor reachable values for lower rpms.

But thats not all regarding boost and PID, just a startup hint. ;)

Of course - my bad. Trying to understand how wastegate duty cycle is controlled. There's enough material on PID tuning that I can get a better grasp by reading but haven't comprehended basics yet I think. Was getting boost undershoot and was able to get to my target by adjusting IMX, but duty cycle is really ragged - looks like it's riding the differential adjustment of PID and I need to understand and smooth it before I move on.

Your goal is a proportional term of zero and your integral term should be just under your dimx at max load. Derivative term is pretty difficult to tune but is only active during rough correction. Increasing derivative will help a bit buy I'd sort out proportional and integral first. What's happening there is you're seeing  your max integral term based on dimx but it is being linearized to come up with wgdc. Sorry if you already knew all that though.

Ignore the wiggles.

D and P are gain scheduled out when lde is low enough... you are way undershooting (riding I-limit), so lde is still very large and D and P are active, causing the wiggle.

Once you get lde under control you won't see the small wiggles like that any more.