Hello,

First, thanks for this long discussion thread talking about tuning EBC. I've made great progress tuning the built MSM engine in my '04 MSM because of that discussion. I limited the Integral factor winding up by reducing delta so the loop starts later, but mostly by setting boost/RPM targets based on real world data. I recorded a 5th gear, WOT run from 2k RPM until 18 psi. Just when I thought I had EBC fairly dialed in I'm starting mostly over. I had the slider sensitivity set at 450 with PID numbers that worked well based on tuning with my boost gauge. Then I recently learned while reading data logs that boost was quickly oscillating around target by ~2 psi, maybe 3. I could feel something was off but my SpeedHut digital boost gauge seems to have more non-adjustable damping than I realized. It was showing the initial over shoot but not the oscillations, if the needle was moving it was such a tiny oscillation that I was unable to be see it bouncing down the road under boost.

The last two days I have been off work, driving back and forth on a few, safer test roads with lower traffic and no side roads. It has a few block long road into a developing industrial road that closes in another two weeks, probably to put up more buildings. It also has onramps nearby where I can circle back and forth to avoid being a stationary target if anybody was to take notice and call police. Twice in the last month I've tested and tweaked the "Boost Control Bias Duty Cycle" table, those RPM columns are also set based on real world data so I can hit and hold target in open loop accurately with minimal drift off target. What is confusing is watching the Boost DC in data logs, I can see when it hits delta but it's not dropping immediately back to the table numbers. It still overshoots a bit (.5-1 psi), then drops about 1 psi below target (am still working on tuning these issues slowly adding more Integral and a little more Derivative has been working) but the loop settles on DC numbers that are much higher than open loop requires to hit target.

I'm tempted to change the lookup table to match the numbers where the PID loop stabilizes but I just lowered DC by 2-3% a few weeks ago to minimize the initial spike. The new, higher flowing FM manifold and outlet pipe needed less DC than before the upgrade. Today I switched back and forth from CL setup mode and advanced modes after dropping sensitivity back to 375 due to the quick oscillation around target as the popup guidance says to do. Sensitivity is now around 340-350 and that oscillation is gone. Once the loop stabilizes (one smaller up/down wave), DC is +10 more than the lookup table at all RPMs up to redline.

Any thoughts as to why there's such a difference between OL table numbers (same as CL setup mode) and where the PID loop stabilizes under sustained boost? I set target down to 16 psi, made progress tuning out the oscillation and overshoot, then dropped to 14 and reworked the DC table with more PID adjustments. Then I set target to 12 psi and played with delta to reduce winding up the I term in higher gears. I might also raise the 12 psi target RPM in the DC table, raising that column slightly will reduce the wind up but also soften spooling in lower gears, right? Lower delta helped for now but it's an idea I hadn't considered while working with the PID numbers.

I'm taking a break to work around the house and after lunch I'm heading back out for more tuning runs. I might also download the SDcard logs to check how each P, I, D term is reacting but that's getting into the deep end of the pool. BTW, still using a serial port on MS3Pro = . I knew tuning to hit and hold maximum target was difficult even with an accurate DC lookup table but tuning CL EBC for all boost targets is another level. My targets for good street control are 7 psi under 30% throttle (using the GT2560R 7.5 psi can), then 8, 9, 10, 12, 14, 16, and 18 psi). I don't want to be cruising along in higher gears and ask for 10/12 psi only for the PID loop to go crazy and BAM, hit boost cut. I'm getting close but it's taking a LONG time to dial it in!

Thank you,
Jess