I am running a FM2 system on a miata with a megasquirt pnp pro and am having issues with closed loop EBC control. It has a 2554r with a ~7 psi wastegate. The EBC is from diyautotune.
I started with I and D set to zero and reduced the P (from 200) till I hit my boost target of 165 kPa (limited to this for now because of the injectors), which happened at a P of 80. I then increased D upto 130 to try and make the oscillations go away but haven't had a lot of success with that. Increasing I causes the boost to overshoot the initial target. Most of the threads that I have read here seem to converge on to much lower PID values than what i have (maybe because my boost target is so low?).

What direction should I take next? Maybe increase P to reduce the oscillations and then increase I to make the boost target. Even with a PID of 200 0 0, I get these oscillations at what seems like wastegate pressure.

I am adding a picture of the logged boost traces for reference. Using solenoid frequency of 39 Hz did not seem to have any significant effect.



My boost settings currently look like this:

 

What firmware are you on? Have you messed with the bias table any?

 

Firmware version is MS3 release 1.3.4, so not the latest.

I did change the boost control initial duty table based on the rough open loop tuning that i had earlier done. Though, having another look at it, I think my 160 kpa column should probably not be 100.

 

You need to update to firmware 1.4 before you do anything else. There were some major changes and EBC control is much better in 1.4.

 

Thanks, I will upgrade to 1.4.1.

Then, I guess, I should start with tuning the bias table using the setup mode and then go to the PID tuning that I had been trying to do with the older firmware.

Can't believe that I did not upgrade the firmware before installing the ECU

 

Upgraded to firmware 1.4.1 and the EBC indeed behaves a lot better now. The oscillation at higher rpms is now completely gone. I started with tuning the bias table in setup mode. Then i moved on to tuning the sensitivity in simple mode and finally played around with PID in advanced mode. I am currently at PID values of 50, 70, and 100 with a sensitivity of 250. Overall the boost curve looks as i want it to, but there is a slight overshoot (around 10kpa) when the boost target is initially met. The overshoot seems to be higher when flatfoot shifting as I hit boost cut (180kpa) in fourth gear and I think if I did a pull from 5000 RPM, it will hit boost cut. I increased D from 70 to 100 and did not really see any difference in this overshoot! Should I be reducing P instead?

Thanks

pull from 2000 RPM


pull from 4000 RPM


pull from ~4500 RPM


flat foot shifting:

 

I also struggled pretty bad with 1.3.4 but managed to get close. 1.4.0 is far, far better (haven't jumped to 1.4.1 yet).