CL boost control has me stumped
11-07-2015, 06:26 PM
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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.
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.
Last edited by 4gordeev; 11-08-2015 at 12:51 PM.
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11-08-2015, 12:51 PM
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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?
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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11-08-2015, 03:44 PM
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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?
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?
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.
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11-08-2015, 06:46 PM
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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.
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.
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.
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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11-08-2015, 06:48 PM
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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.
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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11-08-2015, 07:04 PM
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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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11-09-2015, 07:01 PM
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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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11-09-2015, 07:47 PM
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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?
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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11-10-2015, 10:05 AM
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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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