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Old 11-07-2015, 07:26 PM   #1
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Default CL boost control has me stumped

As always this is probably something stupid but Ive searched and searched and I cant find what Im doing wrong.

I have open loop control set up and it works like a dream. I am able to being boost quickly and hold the desired boost within a psi.

When I switch to closed loop everything falls apart. I use my OL values as the initial values. My settings are:



This is what happens with these settings. As soon as the desired boost is reached (low boost at partial throttle or full boost) the valve ocilates between 0%DC and Max allowed DC.




If I flip to inverted polarity then I get no control what so ever. I cant figure this out. I think Ive tried changing every setting with no luck. Open loop works like a dream which makes me more confused.

Edit: Im using a GM boost control valve plumbed in per diypnp diagrams. More duty = more boost.
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CL boost control has me stumped-80-boostcontrolsettings_82c50f6c370ac07c5b5ac5fc10592dedf974c94a.jpg   CL boost control has me stumped-80-boostcontrollog_a0d4e439543ec1fc3c5badff2192ed2f070c07dd.jpg  

Last edited by 4gordeev; 11-08-2015 at 01:51 PM.
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Old 11-08-2015, 11:27 AM   #2
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I don't think your open duty will only be 50% - set this to 100 % and see what happens...
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Old 11-08-2015, 12:15 PM   #3
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Quote:
Originally Posted by Zaphod View Post
I don't think your open duty will only be 50% - set this to 100 % and see what happens...
I can hold 15psi in open loop with 45% duty. I've already tried 100% and get identical results. It's something else.
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Old 11-08-2015, 01:51 PM   #4
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Your settings aren't using initial value table right now. Start by changing that.

To find your open and closed DC do this.

Start with open loop at 100% all across. Log how quickly it spools. Lower max duty (5% steps) until it spools slower.

Then start at 0% all the way across. Raise it (again 5% steps) until it starts to spool faster/reach higher boost.

This will set the limits that PID needs to function in.

Another thing to look at is your lower limit delta. This is how many kpa below your target boost the PID will kick in. So if your lower limit delta is 30kpa. And your target is 200kpa, then PID will start to affect the output at 170kpa. When using no initial value table your delta should be higher. Like 50%.

Now that we got the basics of boost control tuning done lets look at your logs.

Post your tune, and log file. What is your target boost. What firmware. What hardware.

Right now something weird is going on. How is your boost control plumbed. Is it higher duty=more boost? As in max duty makes the most spool?
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Old 11-08-2015, 04:44 PM   #5
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Quote:
Originally Posted by aidandj View Post
Your settings aren't using initial value table right now. Start by changing that.

To find your open and closed DC do this.

Start with open loop at 100% all across. Log how quickly it spools. Lower max duty (5% steps) until it spools slower.

Then start at 0% all the way across. Raise it (again 5% steps) until it starts to spool faster/reach higher boost.

This will set the limits that PID needs to function in.

Another thing to look at is your lower limit delta. This is how many kpa below your target boost the PID will kick in. So if your lower limit delta is 30kpa. And your target is 200kpa, then PID will start to affect the output at 170kpa. When using no initial value table your delta should be higher. Like 50%.

Now that we got the basics of boost control tuning done lets look at your logs.

Post your tune, and log file. What is your target boost. What firmware. What hardware.

Right now something weird is going on. How is your boost control plumbed. Is it higher duty=more boost? As in max duty makes the most spool?
Crap the screenshot I took I didnt have initial duty table on. I have been using it. I tuned that table based on my open loop settings which are pretty close (at least they were the other day when it was a bit warmer and more humid...)

Im running MS2/Extra 3.3.3 on a DIYPNP

My target is 15psi. Im running a sr20 T25 using the stock waste gate and controlled by a GM solenoid wired per DIYautotune diagrams so that more DC = more boost.

I included a openloop log which shows that open loop works fine and a closed loop log which clearly shows my issues. The pulls were done at different locations so there is some variation in boost.
Attached Files
File Type: msq CurrentTune.msq (110.8 KB, 71 views)
File Type: msl 2015-11-08_14.44.18.msl (319.5 KB, 77 views)
File Type: msl CLnormal50delta.msl (174.4 KB, 133 views)
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Old 11-08-2015, 05:23 PM   #6
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Turn down the sensitivity to like 1 and do another pull. Post log.
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Old 11-08-2015, 06:16 PM   #7
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Sure thing. I did a pull at 1ish sensitivity and a pull at 500(max) sensitivity.
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File Type: msl sensitivity1.msl (136.3 KB, 78 views)
File Type: msl sensitivity500.msl (266.2 KB, 83 views)
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Old 11-08-2015, 07:46 PM   #8
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You are running into the same issue I had. The slider is too sensitive.

Switch to 3.4.0 firmware. Megasquirt Downloads Firmware and Software - Megasquirt EFI

The tuning process is different. Look in this thread for more info.

Here is a post I wrote in another thread. When I mention 1.4 it is the same as 3.4 but for MS3.

Quote:
Originally Posted by aidandj View Post
Its different. I don't think 1.4 is perfect, but it is very very easy to get "close". I talked a bit about it with Savington at MRLS. IMO 1.4 gets you really close really easily, but the bias table is weighted too much in the equation. I have a thread open on msextra where a temperature modifier has been discussed, but i think the bias table just needs less weight.

I have a vm setup with the build tools and am going to try and change it and if it helps a lot I will suggest it to Ken. Currently I don't know enough about the code to ask him to change it, but changing it myself and getting good results will help.

I am also trying to hit 3x my internal wastegate spring with EBC, So tuning is extra hard for me.

PID tuning is the same in 1.4 you just need a very solid bias table. (Which is easy to get)

Once 1.4 is perfected it will be better than 1.3.4, and way easier to tune. You can get very close to perfect using just basic mode.

Here is some info about the new method of boost control



Setup mode is really cool. You put it in setup mode and it uses all of your closed loop boost control settings, except it doesn't use PID. So it uses your target delta, and then treats the bias table as open loop. This way you can tune your bias table starting with the RPM you hit your target delata, instead of just open loop where you have to hold the wastegate closed manually.

So you run setup mode. Find your bias table, then turn on simple mode. Raise the sensitivity of the slider until you get a little bit of oscillation, then use advanced mode to tune out the oscillation. You shouldn't need much P because you are using the bias table to get close to your values, and the PID is for minor corrections.

Somehow forgot to add the link to my thread over on MSextra. Its a really good read.

Megasquirt Support Forum (MSEXTRA) ? Tuning Boost Control With Bias Table (View topic)

Ex of my bias table:

It is not very finely tuned because I have been messing with it a lot lately. But you can see how I don't even start it until 3400. My wastegate does a weird thing where it needs a lot more duty randomly at around 5250, you I have a hump there, and then PID doesnt have to take care of it.

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Old 11-08-2015, 07:48 PM   #9
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RE: duty cycle

on 1.4 you can set min duty to something above what makes your turbo spool fastest (1000% = wastegate closed) and it will hold at 100 until the delta is reached. So really your min and max should be reasonable close together. The PID algorithm will have a much easier time working in a smaller range. You can be more aggressive and get better response.
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Old 11-08-2015, 08:04 PM   #10
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Noob question: Ive never switched to a different firmware. Will I be able to just open my 3.3.3 tune and go on tuning after I install 3.4.0? Or will this temporarily brick my car until I get everything set up?
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Old 11-08-2015, 10:14 PM   #11
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Some things wont switch over. When you upgrade you will get a difference notice. Copy paste this and look through everything that changed.
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Old 11-09-2015, 12:30 PM   #12
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Quote:
Originally Posted by 4gordeev View Post
Noob question: Ive never switched to a different firmware. Will I be able to just open my 3.3.3 tune and go on tuning after I install 3.4.0? Or will this temporarily brick my car until I get everything set up?
typically you just have to reenable the idle control settings, otherwise it should port over without issue.
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Old 11-09-2015, 08:01 PM   #13
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Quote:
Originally Posted by Braineack View Post
typically you just have to reenable the idle control settings, otherwise it should port over without issue.
So I switched to 3.4.0, was a snap and every setting ported over. I haven't had time to do some pulls with cl boost yet.

One thing I don't see though, and it could just be me being a tard, is I don't have a boost bias table. In fact all of the boost options look identical.
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Old 11-09-2015, 08:02 PM   #14
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Awkward. Maybe bias table didnt get ported?
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Old 11-09-2015, 08:06 PM   #15
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If it didn't then you just need to tune PID to make the best of it.

Did you ever try sensitivity 0?
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Old 11-09-2015, 08:45 PM   #16
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So I did some investigating. Looks like the bias table is MS3 only. The other boost control changes did get carried over to the ms2 code.
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CL boost control has me stumped-80-ms2sol_bed7c3ac42fcf7889e63fcc35aaeb35a1214fd02.jpg  

Last edited by 4gordeev; 11-09-2015 at 09:06 PM.
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Old 11-09-2015, 08:47 PM   #17
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Yep thats what i found too.

I had similar issues to you, and got the devs to lower the sensitivity of the slider. Not sure if it also happened in 3.4.0. You might try posting over on msextra.com. The devs respond quickly there and are helpful.

Have you tried a pull on 3.4.0?
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Old 11-09-2015, 09:06 PM   #18
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The sky is falling down outside, so it'll be on the drive to work tomorrow.
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Old 11-10-2015, 11:05 AM   #19
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I did a few pulls on the drive to work. No go. 3.4.0 is giving me the same results. Also tried 0 sensitivity and it still commands to ocilate from hard open to hard closed. Back to square one.
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Old 11-10-2015, 11:13 AM   #20
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tune PID by hand like a man.
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