Does anyone have boost control working?

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AbeFM
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Post by AbeFM »

If you see the other thread on idle settings, you'll find my map signal might have been weird. It wasn't too far off (I kept an eye on it) but it was jumpy. Think it's worth repeating these boost control experiments? I figure not, but if you think it's helpful I'd be happy to set it up.
2000 VVT Miata turbo, MS3Pro

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muythaibxr
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Post by muythaibxr »

IT might be worth trying without a jumpy MAP signal.

Ken
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Post by muythaibxr »

As far as I can tell, boost control is working as it should. I'll make it so you can see the boost duty in the next RC, and add the ability to datalog the PWM idle valve duty. Boost appeared to be doing what it should, although it was doing so VERY fast... once you get the slightest bit above the boost target, it slams slams the wastegate open. I would set differential gain to 0, then tinker with the Control Interval until you get a condition with a slight bit of overshoot, then some oscillation. Then adjust "differential control" until it doesn't overshoot. I'm going to make the Integral term a bit less sensitive to correct for boost creep, etc... in the next RC.

I noticed that you have knock sensing and a second baro sensor turned on... did you do these things on purpose? They were doing odd things here since I don't have them hooked up.

I'd go so far as to recommend turning off everything you don't absolutely need for now until you get a good base tune, and get boost control working.

Ken
AbeFM
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Post by AbeFM »

They are both on purpose, I can't say the baro is doing much for me. The knock sensing I really want to have, it rarely ever triggers - generally when it hits overboost or overrev cuts.

I'll turn off baro and try the boost control again - but I think I was seeing the same thing you were - hitting the target made it come right down right fast instead of slowly backing off.

Any suggestions on the P term?
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muythaibxr
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Post by muythaibxr »

I'd leave the P term alone, and adjust the Control interval for now. Once you get it slowed down a bit, you can adjust the P term. When you get the P term close, it should cause a bit of oscillation around the target boost point.

The next RC will have the boost duty gauge and have it loggable, so we can see exactly what it's doing in your install.

Ken
AbeFM
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Post by AbeFM »

Ok, maybe I'll wait for that. While waiting for a response, I kept my old settings except:

Interval: 50ms
P: 50
I: 0
D: 10

And got the same behavior, only slower - build up to target boost, then slow/steady drop to vacuum again, so I went back to my manual which is very fast if not always precise and I'll wait for the new RC. Thanks for putting it in!
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Big Bronze Rim
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Post by Big Bronze Rim »

Out of curiosity Abe, when you use IAC1 as your BC output, do you need to bring 12V power to JS9, as if you were using it for stepper motor control? Or do I just wire my FET to run off of say, JS0 without worrying about the 12v power.
AbeFM
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Post by AbeFM »

Interesting, I hadn't thought about it - I did run the +12 just since I was doing it according to the manual at the time, I hadn't yet settled on which outputs to use for what. I'd be curious to pull the plus 12 off and see what happens. My feeling is, though, that it is needed since on the daughtercard there are chips between the CPU and JS0.
2000 VVT Miata turbo, MS3Pro

Contact me if interested in a MS-II 2nd gen NB Miata PnP board.
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