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Old 05-16-2015, 10:26 PM   #1
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Default MS2 Boost control - Am I missing something?

I have DIY EBC valve plumed in so that the unpowered valve switches to wastegate pressure, for safety. I'm using a MS2 3.3.2 which isn't the MS3 skinned one. Boost control works, just not quite like I want it.

From what I can see, the valve always wants to stay at 0% duty unless I cross over into boost, where it will switch to 100%. According to the menu More DC = More boost, so why is the valve always at 0% if there is no boost?

I've inverted the valve settings so I can get the valve to close at idle and such, that is venting the wastegate = 0% DC, this is what that looks like. I am using the initial value table, full of 0% DC, yet it still snaps to 100% DC which is bad for spool as seen here. My wastegate is set pathetically weak, like 130kpa, so any amount of duty on the valve bleeds a lot of boost.




If I invert the valve again, it still sits at 0% DC till positive pressure. I don't really care if it matters to spool, I don't want that. I obviously changed the initial value table to nothing but 100% when I invert the valve, I even added a 10 map line filled with 100%.

So, am I missing something or is this just how it has to be?

These are the inverted settings here...



Thanks for looking!
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Old 05-16-2015, 10:52 PM   #2
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Have you set it up in open loop first?
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Old 05-16-2015, 11:00 PM   #3
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Closed loop needs to have the solenoid wired for more duty cycle = more boost.

whats happening is its trying to spool to target boost by turning up the duty cycle, but it can't because right now 100=no boost.
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Old 05-16-2015, 11:18 PM   #4
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Good answer, obvious only in hindsight.
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Old 05-16-2015, 11:19 PM   #5
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Nitrodann is right though, make sure open loop works.
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Old 05-16-2015, 11:54 PM   #6
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I understand it wants 100=more boost, but no matter how I set it up it will only use 0℅ duty cycle at idle.

I have changed the valve polarity to set it up both ways, there's no need to rewire the valve.

I don't see what open loop has to do with this, it works fine it just won't keep the valve closed from idle. I've entered bogus open loop values and I still get wastegate pressure till I'm actually making boost.
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Old 05-16-2015, 11:56 PM   #7
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Post your boost target table.
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Old 05-16-2015, 11:58 PM   #8
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Closed loop holds the duty cycle at 100% until your MAP is inside the delta. So if you target is 150, and your delta is 30. Then closed loop will hold the valve at 100%, then go to your initial duty and try and adjust.
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Old 05-17-2015, 12:49 AM   #9
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It uses the open loop table as a lookup table then closed loop PID adjusts it from there.
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Old 05-17-2015, 12:50 AM   #10
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No it doesn't, it uses the initial duty table to get the initial duty, and then uses PID to go from there to target boost.
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Old 05-17-2015, 01:36 AM   #11
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This is what I am trying to say, while at 0-100 kpa my valve sticks at 0%. As soon as I get to 101kpa, it jumps to 100% till the delta. You can see it doing this in the log, and you can see it knows what's up and still manages to hold steady

Open loop is entirely disregarded, using the lookup table is optional. My boost target table is 150kpa all across, and the initial table is 100% everywhere as well.
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Old 05-17-2015, 01:38 AM   #12
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Being at 0% in vacuum won't effect spool. Wastegate will stay shut.
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Old 05-17-2015, 01:39 AM   #13
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Also wastegate set that low might effect spool if the wastegate is getting blown open.
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Old 05-17-2015, 01:43 AM   #14
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So that's how its supposed to be? No way to change it that I can see

I just backed the thing off while I figure out boost control, it manages to dump it pretty quick. I'm sure I'll need to retune it a bit after I mess with the preload again.
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Old 05-17-2015, 01:45 AM   #15
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Its a feature. You don't want your solenoid uselessly cycling 24/7 unless its in boost. I think with the current code you can set the minimum duty cycle and it will stay there. But I just reported that bug and it should be fixed in the 1.4 release.
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Old 05-17-2015, 03:27 AM   #16
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Quote:
Originally Posted by aidandj View Post
No it doesn't, it uses the initial duty table to get the initial duty, and then uses PID to go from there to target boost.
Depends which MS and which firmware.

Dann
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Old 05-17-2015, 05:09 PM   #17
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If there is an initial duty option it uses that. Maybe on some older firmware it uses the open loop. But I've never seen it.

Deezums, make sure that your wastegate isn't blow open. Do a log with open loop control and duty cycle set to 100%, and crank the preload on your wastegate....don't blow your engine, just run it up to 170kpa or so.

Then do the same thing with the wastegate where it is and make sure the spool is the same.
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Old 05-17-2015, 05:16 PM   #18
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Also set your control interval to 51ms, currently your closed loop is making changes faster than your valve can react. This is also fixed in the newest betas.
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Old 05-17-2015, 05:27 PM   #19
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No rain today, so I can actually play with boost control. I plan to go out and mess with it soon.

I'm pretty sure my MS2 disregards all open loop tuning tables when you switch to closed loop, which is why I kind of skipped right over it once I knew the valve worked. The Closed loop table is separate from the initial value table, and you can't even edit the closed loop values if you use closed loop.

As fast as my valve seems to react I hope to not use the initial value table at all. I don't like how the initial table option controls idle, and I don't think it will be much better with boost than idle. Just me making weird assumptions though...
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Old 05-17-2015, 05:30 PM   #20
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The initial value helps a lot. Without digging into PID controls too much it basically gives the closed loop equation something to start off of. It makes a pretty big difference in the overall picture. Test your wastegate, make sure its not blowing open. Then do some pulls in open loop to find your initial values, before you start start tuning PID. Start at 100, and lower by 10 until you effect spool (mine was 65% duty cycle). Set your max duty cycle to that. Then lower by 5 each pull and compare the logs to find at what RPM you get what boost, at what duty cycle. Then fill out the initial duty cycle, and start with P=100, and lower it until you get a bit of a overshoot, then tune I, etc, etc.
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