Can't seem to figure this out - been playing with idle PID, which has helped somewhat but still can't get it to work correctly. The car is heavily modified (1.8T 80mm throttle, RS4 MAF in 100mm housing, cams etc etc). I have the throttle maps sorted so that throttle airflow matches MAF airflow and the fueling is pretty much spot on.
Just can't work out why the ECU is reducing the ignition angle, which causes the RPM to decrease, even though the RPM is below requested RPM!
I am probably missing something simple but tracing through the idle PID section in a google translated FR is near impossible.
What should I be looking at to stop the ECU reducing the ignition angle to stop the RPM oscillations?
I am in the exact same problem. I have the RS4 MAF on my S3 1.8t, scaled it, but got the same oscillations. I already whooped around with KFWDKMSN which already made it better already. I found out in another thread that KFMSNWDK also needs some modifications so I already did that but I need to test it right now.
My car is also pretty modified with performance cams, dahlback intake etc. etc.
I also increased (advanced) ignition timing at idle because I was seeing -12 atdc most of the time, but I would never pull it more than 12-14 for idle. (also I dont care much if its running a bit rough at idle because of the cam overlap timing)
With the ignition flying around that much this is not a "great" idle.
You have almost 20 degrees of ignition on idle, and this is not a solution to anything. I'd idle it with way lower ignition, as now there's not enough to properly counteract things like the power steering or AC turning on.
This is also the reason you have RPM breaks when it's coming down.
The way you did it is a giant hack, and not the correct way.
The correct way is:
1. Modify KFMSNWDK/KFWDKMSN to actually match your throttle characteristics (!). This is the prime reason you had negative advance and so on, because it was keeping the throttle too open for a given load. And then using ignition to back off torque. Most likely rl_w > rlsol_w all the time and it was trying to compensate.
2. Once that's done, yes adjust throttle PID.
3. Adjust torque reserve.
Thanks for pointing Prj. I just checked my log again and as you are saying rl_w > rlsol_w.
FWIW here 2 logs from where I begun today and where I already am, I noticed when modifying KFWDKMSN it already stabilized a bit more but still has the drop to 600 rpm and the bump to 1600 rpm once in a 2-3 secs instead of going up and down from 600 to 1500 every second, I will calibrate like Prj just adviced and will give an update here when I am on it again.