Sklr

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:

shuiend

iTrader: (24)

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

Sklr

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.

shuiend

iTrader: (24)

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.

Sklr

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

Sklr

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:

Savington

iTrader: (31)

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).