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Old 05-07-2014, 09:53 AM   #1
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Default MS EBC Duty Cycle question

I set up my EBC last night. I have heard "you don't want to make it so that MegaSquirt has to intervene in order for your wastegate to open" which makes perfect sense. If something goes wrong with that signal wire and your wastegate never opens...boom.

I hooked up my EBC (DIY Auto Tune one) according to the directions on DIY Auto Tune, put in slightly bigger brass barbs to match the WGA barb, and then tested by blowing into one end of the EBC. with no power hooked to the EBC, air flowed through correctly from one barb to the other, and the 3rd hole (with no barb) was blocked.

But the term "duty cycle" confuses me a bit. When I hooked everything up and opened up Tuner Studio my duty cycles were all set to 100--and yet, the WGA was working as if no solinoid was in the way.

Did something get switched, and my MS is now having to intervene 100% of the time in order make my WGA work as stock? Or is that just the phrasing, and with, say, 90% duty cycle the EBC is getting a ground 10% of the time?

I noticed it said my polarity was "inverted" which I assumed was because I go from 12v+ to solinoid to MS ground (Normal polarity would be MS providing 12v+?)

Basically, I just want to make sure that if one, or both, of those signal wires to the EBC gets sliced somehow that my EBC is still going to be OPEN (wg pressure) and not closed (engineboom pressure).

---

Am I correct about "normal" polarity being 12v+ from MS to solinoid to fixed ground? If so, wouldn't it make more sense to set it up that way?

Seems like as-is, if my wire running through my firewall from EBC to MS accidentally shorts and grounds out, I'll be having a bad day.

Sorry.. got very wordy but I think you get what I mean.
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Old 05-07-2014, 09:57 AM   #2
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Also, flamesuit on, but I've been searching and even dug through msextra/megamanual.

Quote:
Boost Control
This system is used to control the boost pressure from a turbo via a fast acting valve on the waste gate, but it is still EXPERIMENTAL and must be used with caution!



DigiKey part numbers:
Farnell part numbers

10K resistor = 10KQBK-ND
100R resistor = 100QBK-ND
IRLZ44 = IRLZ44N-ND
10K resistor = 543-627
100R resistor = 543-147
IRLZ44 = 229-0765


Please note: Above part numbers will need checking, some components will come with a minimum order in multiples of 5 and 10.

Pin Usage: JS0, JS2, JS11 and FIdle.
See HERE for more on pin usage.



The Solenoid Frequency is the pulse width that is used to control the solenoid, this will need to be experimented with to get your system to react best to the controller.

The Controller Interval is how often the ECU will look at the boost pressure and adjust the setpoint in mSecs.

The Proportional Gain is how hard it seeks the target.

Differential Gain means how it will react to sudden changes, it's roughly a predictive term, but for best results it probably has to be kept to a small value. Tune proportional first, leave differential for later

The Output Polarity is for setting the valve so it operates the right way, generally as PWM Increases the Boost Increases.
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Old 05-07-2014, 10:40 AM   #3
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Is this a MS1 or MS2? Can you post a copy of your MSQ?
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Old 05-07-2014, 11:09 AM   #4
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Quote:
Originally Posted by Matt Cramer View Post
Is this a MS1 or MS2? Can you post a copy of your MSQ?
MS2E from Reverant.

I'll post up my MSQ when I'm done with work, but I'm running open loop, polarity is inverted, and my duy cycle table is all 70% right now (100% was wastegate pressure).

I haven't changed anything EBC related from the "base tune" that came with the MS2E except to lower my duty cycle table from 100% to 70% which has me hitting 10PSI pretty quickly and holding 10PSI to redline on a 6psi WGA.
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Old 05-07-2014, 11:15 AM   #5
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great advice: learn.
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Old 05-07-2014, 12:14 PM   #6
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Quote:
Originally Posted by Braineack View Post
great advice: learn.
Seriously?

I have the EBC set up and working correctly. I want to make sure that if something goes catastrophically wrong with wiring it wont go catastrophically wrong with my engine.

I checked the stickies, found this https://www.miataturbo.net/megasquir...pnp-ebc-62711/ Yeah, it's for MS1 but it seems to be applicable, but he says he just used the defaults.

I followed the directions from DIY auto tune and from reverant and stated above that I have followed them and left the defaults.

I checked the mega manual and MSExtra and even posted above the content from that manual which applies--and doesn't answer my question.

---

I'm not sure what else you're expecting of me here. I didn't find my answer in any of the above resources that I searched and checked, so I came here to a group of very knowledgeable people and asked a question.

If you'd rather, I can spend an hour in my garage with my multimeter tonight and try to figure out what all these settings do. But I personally felt that I had done a good amount of research before asking this question.
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Old 05-07-2014, 12:16 PM   #7
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Quote:
I have the EBC set up and working correctly. I want to make sure that if something goes catastrophically wrong with wiring it wont go catastrophically wrong with my engine.
I think that is what the overboost protection is for....
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Old 05-07-2014, 12:21 PM   #8
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Yes, they put overboost protection in your megasquirt so that you can ignore actually setting up the EBC correctly.


Brain, I'm especially surprised at your post above seeing as how it was YOUR post that got me thinking about all of this in the first place.


Post 32 here: Overboosting/boost creep - Page 2 - Miata Turbo Forum - Turbo Kitten is watching you test compression.
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Old 05-07-2014, 12:35 PM   #9
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I've been confused by this as well. The manual here

Boost Control

Says that for open loop more duty is = less boost/more signal to the wastegate. IE 100% means the solenoid is totally open and giving the wastegate full signal and 0% means the solenoid is totally closed and the wastegate is getting no signal.

Polarity in the open loop boost control just reverses how those values get read by the MS it seems. IE if when you set it to Normal it acts as above and 100% is full signal to the wastegatae then flipping polarity to Inverted would make 100% no signal.

I'm still unclear on how the duty table relates to the closed loop boost control if at all.
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Old 05-07-2014, 12:39 PM   #10
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What version of firmware are you on? The duty cycle has been reversed in 3.3 so more duty = more boost. If you ever plan on switching to closed loop control you have to make sure polarity is set correctly so that more duty is more boost. As long as you have overboost protection enabled and set to a sane value an EBC control failure will not be an issue.

Megasquirt MS2/Extra Loading firmware and Upgrade Notes

Closed loop control is now done differently.
Megasquirt MSEXTRA / MS3EFI • Boost control change testing (MS2 and MS3) (View topic)
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Old 05-07-2014, 12:42 PM   #11
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Quote:
Originally Posted by midpack View Post
What version of firmware are you on? The duty cycle has been reversed in 3.3 so more duty = more boost. If you ever plan on switching to closed loop control you have to make sure polarity is set correctly so that more duty is more boost. As long as you have overboost protection enabled and set to a sane value an EBC control failure will not be an issue.

Megasquirt MS2/Extra Loading firmware and Upgrade Notes

Closed loop control is now done differently.
Megasquirt MSEXTRA / MS3EFI • Boost control change testing (MS2 and MS3) (View topic)
No wonder this is so confusing.
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Old 05-07-2014, 02:50 PM   #12
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To be clear, I will still get my overboost protection set up correctly, I just don't feel that a failsafe like that should make it so that I spend less time setting up the EBC properly in the first place.

Thanks for the replies. I'll post up my firmware version as well as my .msq as soon as I get a chance to get my laptop out of my car and grab the information--sometime this afternoon.
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Old 05-07-2014, 08:03 PM   #13
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Here's my MSQ. Appears to be 3.30. Do I just need to switch from "inverted" to "normal" ?
Attached Files
File Type: msq 2014-05-07_17.59.42.msq (94.2 KB, 68 views)
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Old 05-07-2014, 10:14 PM   #14
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If you're using open loop then switching from inverted to normal just changes what the values in the table equate to IE does 100 = no boost or does 100 = all boost.

I'm not even sure what that means for the closed loop tuning or if it means anything at all. I would assume nothing since it is disabled under closed loop. Seems like people just use it for reference to see whether the solenoid is reacting or not. The closed loop mode uses a different table with kPa targets and the PID settings.

Don't take my word for it though since I just started into tuning closed loop as well and I'm around the same place.
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Old 05-08-2014, 12:23 AM   #15
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From MSextra on MS3 boost control:

Quote:
Tuning open-loop boost control
Open-loop boost control tuning is very simple. The main tuning table appears below:

Image openloopboost

Notice that areas which should have low boost have higher duties. This is because a higher duty should correspond with a more opened wastegate, which should correspond roughly to lower boost. If while tuning open-loop boost, higher duty results in higher boost and closed-loop boost control will eventually be used, toggle the Output Polarity setting to the opposite of its current setting.
So what they're saying is that higher duty cycles should let MORE air through.. but y'all are telling me that that's the opposite of true?
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Old 05-08-2014, 01:04 AM   #16
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Forget everything the documentation says about EBC tuning. It's wrong for 3.3 an up firmware.

With 3.3 the duty cycle behavior is reversed, more duty means less air to the wastegate and more boost. Read over the first post of the msextra thread I linked, it explains how to setup closed loop control. Hint - you have to enable and setup the "Initial Values" table with all 3 PID values set to 0. Tuning Initial Values is like tuning open loop control. Once that's dialed in you can use the slider and PID values to fine tune control.

This is the future of MS EBC control. At some point in the beta releases they renamed it to Bias Table and made it required.

I don't understand how requiring the tuner to setup boost control with open loop then adjusting PID values is somehow easier than just adjusting PID values but whatever. Maybe it will make more sense once I start tuning it.
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Old 05-08-2014, 01:35 AM   #17
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Thank goodness you posted this. I was going by the documentation and just got back in from trying to set up closed loop.. Was about ready to choke a bitch.

I and D both set to 0, the document says to tune P first starting at 100 slowly decreasing.

Well, with polarity "inverted" (the default, and what seemed to be correct per documentation) I couldn't get above wastegate pressure (about 4.5psi after pressure loss from fmic). Didn't matter what my P was set to.

With polarity set to Normal, I hit boost cut of 12psi no matter what anything else was set to. Dropped by target boost down to 7psi and tried a P of 95, tried a P of 30.. Didn't matter. I would over boost by 5psi,hit my boost cut, and nearly throw my tuning laptop out my window.
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Old 05-08-2014, 09:42 AM   #18
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Quote:
Originally Posted by midpack View Post
Forget everything the documentation says about EBC tuning. It's wrong for 3.3 an up firmware.

With 3.3 the duty cycle behavior is reversed, more duty means less air to the wastegate and more boost...
Sorry, beating a dead horse here, but this isn't true for me. At least not with the default settings.

Am I supposed to have the polarity set to "Normal"? Because it defaults to Inverted.

Unless I have it hooked up wrong. But per the instructions Dimitris sent me:
Quote:
Green - Boost control output. Connect this to a boost control valve. The other wire of the boost control valve needs to be connected to a switched and fused 12V source. A 5A fuse is recommended.
Which is how I have it hooked up.

As of right now I'm still running open loop because closed loop causes me to either be at WG pressure or infinitiy pressure depending on my settings, and with Open Loop, Polarity set to Inverted, Duty Cycle - 100 I'm at WG pressure. I dropped Duty Cycles to 70 across the board (basically using my ebc as an mbc kindasorta) and i hit about 9-10psi pretty consistantly on a 6psi wg.

---

EDIT: and yes, I'm on 3.3. In a MS2E built by rev if that changes anything significantly.
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Old 05-08-2014, 09:49 AM   #19
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if you're getting overboost and seeing no difference between P100 I0 D0 and P20 I0 D0 then you've hooked something up wrong.

P100 I0 D0 should be wastegate, regardless of your targets.
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Old 05-08-2014, 09:59 AM   #20
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Quote:
Originally Posted by Braineack View Post
if you're getting overboost and seeing no difference between P100 I0 D0 and P20 I0 D0 then you've hooked something up wrong.

P100 I0 D0 should be wastegate, regardless of your targets.
Ok. Then having my polarity "Inverted" is the way it needs to be. Which makes it so that open loop 100 duty cycle is WG pressure.

If I set it to "normal" I get hella overboost (man that gt2554 spools quick) even with p100 i0 d0 with target boost of like 7ishpsi (150 kpa i believe).

I'll try again on my lunch break. So, if I set my target kpa to 150 and p0i0d0 I should at least hit 7psi and possibly overboost a bit, and then fall back to 7psi, correct?
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