cj.surr Posted September 6, 2019 Report Share Posted September 6, 2019 I'm having an issue trying to dial in the PID settings for closed loop boost. I get a slight boost spike on spoolup. I think it is because the P-value is adding duty cycle immediately when the boost control transitions from Stage 1 to Stage 2. This correction doesn't make sense because the wastegate is transitioning at this time and any corrections will be delayed. If I lower the P-value sensitivity, I don't get all of the high RPM correction that I need (my setup is prone to creep). Are there any recommendations for working around this issue? It seems to me like there should be a delay before correction when transitioning between Stage 1 and 2. And/Or, separate P-value sensitivities set for Stages 2 and 3. Thanks CJ Quote Link to comment Share on other sites More sharing options...
Adamw Posted September 7, 2019 Report Share Posted September 7, 2019 Post the log and tune. Can’t tell much from a screenshot. Quote Link to comment Share on other sites More sharing options...
cj.surr Posted September 8, 2019 Author Report Share Posted September 8, 2019 Unfortunately the log is too large to attach so it's shared here: https://drive.google.com/file/d/1cpi8_mGRGqu-0M3mX6lqFkx4wJH-lcbG/view?usp=sharing Thanks E28.pclr Quote Link to comment Share on other sites More sharing options...
Tim D Posted September 8, 2019 Report Share Posted September 8, 2019 45 minutes ago, cj.surr said: o It looks like the wastegate duty cycle table needs tweaking first, it doesn't look very tuned?. The I-term is having to do a lot of correction to maintain steady boost. Once it's tuned, the PID terms will have less work to do and it should make tuning a lot easier... Quote Link to comment Share on other sites More sharing options...
cj.surr Posted September 8, 2019 Author Report Share Posted September 8, 2019 I wouldn't say the DC table is perfect, but it's about as close as I can get it. (IWG on a big, fast spooling turbo being fairly inconsistent). The I-value is pulling about 2%, not a lot. Seems like it wanted about 19% DC to hit target, and in my WG table it was 21%. I think the problem is that when transitioning into Stage 2, the DC started at 26% because the P-value is immediately being applied (Table value is 21%). It tapers down towards 20% but since the WG has a delay (at least a few tenths of a sec), the higher DC initially does contribute to overshoot. Quote Link to comment Share on other sites More sharing options...
Adamw Posted September 9, 2019 Report Share Posted September 9, 2019 Can you try another log with the following changes: Stage 1 duty 85% Stage 2 on 55Kpa Stage 3 delay 0.5sec Derivative gain 1.5 Quote Link to comment Share on other sites More sharing options...
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