1SWEET7

iTrader: (1)

I am so frustrated with this boost controller. I have read tons of ways to set it up and I just want to get it working correctly or I am going to get something a little more user friendly. I have it reading in PSI. It feels like my boost comes on very slowly at first and then at about 3800 rpm it pulls good. If I go WOT in fourth from a slow speed it builds boost VERY slowly. Also if I go WOT at a low RPM in 1st or 2nd it bogs for just a second then picks up fine. My main confusion is the "set gain" setting. I see people with settings as low as like 10 to as high as like 170. Is this setting like the "set" reading of psi x 10 like 110 would be 11 psi? Here are my current settings that I have. I am on the stock turbo and want ~8psi.

Set = 40%
Gain= 15%
SetGain = 12 (also tried this at like 70-90 and it didn't seem to do much.) This can't be a % value because it goes up over 100, so I am just so frustrated!

I have read the Evo instructions as well as a bunch of others, but I am still having problems, so please don't just post those Evo instructions.

Rob XX 7

iTrader: (8)

Im trying to remember how I set it, but some of it is percentages and some of it is PSI, but lets say you are supposed to set PSI and you think its percentage and you put 40 then it would be 4 psi.

Try raising the values slowly, but first set your max boost more conservative. The only way to figure that controller out is to have someone else in the car and take it on a nice open road and start raising the values until its where you like it.
Once you figure it out it gives great control.

Once you have the car boosting where you like it and you got the hang of it set your max boost higher and raise everything again.

MaczPayne

iTrader: (5)

I used 3rd gear wot pulls to adjust mine. I adjusted 'set' until I got my desired boost, then 'gain' until boost remains somewhat steady up to redline (it will fall off a bit because of the turbo's limitations). 'set gain' should be set as close as possible to your boost pressure (in your case, psi), without spiking.

I'll go check my settings at lunch.

1SWEET7

iTrader: (1)

I am confused as to where to set the "set gain" level to have it close to where my boost starts. It is very confusing to me and there are so many varying settings that I cannot compare to my own. I want ~8psi so then my "set gain" should be around 8 or 80?

Sandbagger

Are you running the stock turbo? S4 or S5? I did notice you have a ported wastegate of 33mm, are you running a hybrid?

The reason I ask this first is because it will affect your response (turbo lag). S4 is slower than S5 and a Hybrid will spool slower than a stock turbo.

Have you tried running the car with the ebc off, as a comparision to with it on? Any difference in spool time?

I don't remember the max percentage on the set gain, but I know the HKS unit goes up to 200%. The Profec may be similar...

Maczpayne: I thought the GAIN was for adjusting spike/drop-off and SET GAIN was for response?

MaczPayne

iTrader: (5)

Correct. Did I say something different?

Set Gain is the point where the wastegate begins to open, you want the value to be near your actual boost value, so if you're going for 8psi, you want it somewhere near that. I'm guessing your value should be less than 80. Try 65 or 70 and work your way up, in increments of 2.

Also, set gain is not a percentage on the BSpec II

I forgot to go check my settings at lunch, I will later on today after work! They are for 10psi, I shall have them for you to compare.

1SWEET7

iTrader: (1)

I am running the stock S4 turbo w/33mm ported WG. I have messed with it a bunch today and it seems to be working pretty good now. I had never played with the "set gain" that high, and I feel stupid now that I hadn't. I have "set gain" around 70 now. I get a hesitation when I romp WOT from low RPM's but I don't think that is boost controller related. I was very confused and after I posted this thread I found a good thread on another Mazda forum and there were plenty of posted settings on there. That helped a lot to get into a ballpark of where I needed to be. It's hard to think straight when your frustrated. Thanks for the help guys.

MaczPayne

iTrader: (5)

Frustration is never good when you're trying to learn something new. Glad you have it worked out somewhat though! Once you learn it, it will all make sense. If you want to fine-tune it, you can get even better response and less drop-off.

arghx

iTrader: (3)

Don't believe everything you read on the internet. Just because somebody got lucky with some combination of settings doesn't mean they understand the device. I for one have never used a Spec II. Ha! so why should you believe me, you ask? Because I know how boost controllers work, and because I have hands-on experience tuning them using graphical analysis (logs); therefore when I read instructions I have a good idea what they are talking about. Allow me to first explain some basic boost control design principles. Then we can discuss the Profec B spec II in light of those operational principles. The Greddy solenoid happens to use the exact same solenoid as the Apex'i Power FC and AVC-R, two systems I understand more than most people. Therefore I am going to dissect one of my very own Power FC boost control logs and use it to illustrate how I believe the Spec II works.

I'm sure many of you know how an internal wastegate works. You apply pressure to the actuator, and once the pressure reaches a certain level the swing valve slowly opens, until it is fully opened at the rated spring pressure. Boost control solenoids reduce the amount of pressure in the actuator in various ways, depending on how the system is set up. So let's get into the operation of the solenoid itself. Pictured here is actually a Perrin 3 way boost control solenoid for a Subaru (original pic is from their website). The basic design of 3-way boost control solenoids is the same. So I'll label it like a Greddy/Apexi/Denso solenoid in the typical internal wastegate configuration.



here is the solenoid with no voltage applied. The normally open (NO) port is flowing pressurized air to the wastegate.



here is the solenoid with voltage applied. The normally closed (NC) port is now open, venting pressurized air from the wastegate. The boost controller rapidly cycles the solenoid on and off, switching between pressurizing the actuator and venting it. The more the solenoid is on in a given timespan (the duty %), the more air is vented and the more the boost will rise. The word "duty" is thrown around a lot. Perhaps this illustration from the AVC-R manual will make it more clear what that means:



Does everyone see now how 100% or near 100% duty closes the wastegate, and 0% opens it up? At high duty, air from the pressure source is effectively blocked completely from reaching the actuator. At 0% duty, you are running wastegate pressure. Pressurized air reaches the actuator unimpeded.

Ok so now let's get back to the Spec II. Many people have struggled to understand how this thing works because it's not quite as simple as the "fiddle with it till it works" method of the simpler controllers. Let's bust out the instructions again:



The "SET" value is our base duty value, or at least has a lot to do with it. All of the self adjusting logic in the EBC is presumably based off of this. AEM sells a dumber-than-dirt, completely open loop boost controller (called the TRU BOOST) that relies mostly on this function. You're telling the EBC a baseline value for how often it should block pressurized air from entering the wastegate.

To understand "GAIN" conceptually, think about a cruise control system. If I've got cruise control on and I start climbing a hill, the cruise control computer needs to have some guideline for how it can respond now that the car is slowing down. Given the rate at which it is decelerating, how far down can the cruise control actuator push the pedal? How quickly should it push down the pedal? Should it slam down the gas, then let off quick (GAIN too high), risking a cycle of overshooting or undershooting the target? Or should it ease into the gas and then slowly let off, which could result in you never getting close to the target speed (GAIN too low)? There has to be some kind of balance between the two given what you want out of the control system.

Finally, let's get to "START BOOST" aka "SET GAIN" . Remember that the solenoid decreases the amount of pressurized air in the actuator by blocking the pressure source. Now ideally we want to block all the air from hitting the wastegate actuator for a period of time (duty cycle near 100%), shutting it completely (if the spring is stiff enough). Then we would open the wastegate up as late as possible, but hopefully without overboost. If the spring is stiff enough, the wastegate opens when the duty drops from near 100% down to near the SET value (taking into account corrections made by the feedback loop system). SET GAIN should always be lower than your target boost level

Ok now I'm going to throw something at you that could either have everything make way more sense or or just confuse the hell out of you further. This is a log of my boost controller duty cycle on my Power FC. You can only log duty cycle (into a usable log) if you are controlling your boost through a standalone or other higher end EMS. The Power FC doesn't have the same type of settings as the Spec II, but a log of a duty cycle curve illustrates how the settings work. This is a 2nd gear pull, maybe 1/3 throttle on my T04R. The boost builds slowly because the throttle isn't open much but the curve (middle graph, in blue) is relatively stable (fluctuates within a half psi range) and it will help me get my points across.



Follow the green line at the bottom. Once I get into boost, the duty shoots up and flatlines near the top as the wastegate is held shut. Once the SET GAIN pressure is reached, duty drops down to a range near the SET value as the wastegate opens and more air is allowed to reach the actuator.

With the gate open, the boost controller makes now observations of the boost curve. It uses calculus to determine how much the boost is fluctuating and how fast it is fluctuating, just like a cruise control computer does calculations when figuring out how much throttle to apply. Using the "Duty" and "Gain" settings, the Profec calculates how it will change the curve of the duty cycle in response to observed fluctuations in the boost curve.

Adjusting the Spec II

Ok. Maybe that was a lot. Maybe you only picked up 20% of what I just put up here, and you don't care anymore and just want to know how to get your boost dialed in. Well hopefully the wastegate does flow enough and hopefully the spring pressure is appropriate for what you are trying to do boost-wise or you'll never be that happy with it.

The first thing you need to do is stop looking at your boost gauge. Stop. I see you have an Rtek 2.1 . Datalogging is the most powerful tool of the tuner. You need to be logging every pull you do as you adjust this thing and observe how the curve changes. Here is what I want you to do:

1) Turn the boost controller off completely. Now make a log of RPM vs boost on your Rtek. Observe the boost curve. You say you want 8psi. Going that low is going to be tough if you have an open exhaust, and I think that's part of your problem here. To get that low you will have to try and set your wastegate tension to about 6psi with no boost controller installed. I believe lengthening the actuator reduces tension and shortening the actuator increases tension, but double check that.

2) Assuming you can get the spring pressure a couple psi lower than your target boost, re-enable the boost controller. Return the settings back to factory:



3) Follow the basic outline of what the instruction manual says ^. Gradually increase the SET value but leave the other settings alone for now. Observe the boost curve. Once you get the SET value to the point where you are reaching your target boost level but falling off after that (you can see this in your datalogs), begin to dial in the GAIN setting. Keep adding in GAIN until you start seeing overshoot or drastic oscillations in the boost curve, at which point you should dial it back slightly until that goes away.

4) Slowly increase the START BOOST/SET GAIN in say 2psi increments from 0. Observe the boost curve each time. Once increasing the SET GAIN results in a spike, you have increased it too high. Put it back to where it was before.

5) Now you have two choices. You can just leave the settings alone assuming the boost curve is decent, or you can really start fine tuning it, jumping back and forth among the SET GAIN, SET, and GAIN. Try going higher in SET GAIN and compensate with lower SET. See if that does anything. Try other stuff. You may be able to get a small improvement in the boost curve in these final steps.



So I guess in conclusion... trust the instructions. When you know what you are reading, they make sense. Whoever is telling you to set your SET GAIN/START BOOST to 70psi is succeeding because of some level of idiot-proofing in the Profec. Because of the high SET GAIN, the Spec II is keeping the wastegate duty near 100% for a long time until the feedback system overrides and starts cutting the boost down, probably through a drastic swing in the solenoid duty cycle curve. There's a good chance that these people have pretty ugly boost curves, or their boost curves could be improved at least. But you can't see your real boost curve when you've got one eye on the road and one eye darting between the tach and the boost gauge. It's a horrible way to tune anything.

1SWEET7

iTrader: (1)

Thank you very much for that. I thought I had a decent idea of going about tuning this thing, but maybe I will do what you said and start from scratch. I am still running my stock S4 turbo and the stock non adjustable actuator. I can however hold 5.5-6lbs of boost with the controller off, i.e. stock boost with no creep whatsoever. I think you are confused at what I said maybe though, I have it set in psi so 110 = 11lbs and such. I had my "set gain/start boost" set very low and just today I raised it to where it should be I suspect at around 70=7psi. I basicly had everything working great except that it felt like my boost wasn't coming on quick enough, but it seemed to be better after tweaking with it today. Again thanks for explaining it more for me and whoever finds this thread in the future.

arghx

iTrader: (3)

ah you're right about the 3 digit PSI display, page 14 of the manual. A simple quirk of the profec, my mistake.

Rob XX 7

iTrader: (8)

I know when I had the instructions in front of me along with the controller and driving the car it became very clear to me, but without any of it in front of me I forget how I did it.

I also no longer have that controller, not because it was not a good controller, but because I went with the built in function of my car's ECU.

That 3 digit display and the fact that some of it is percentages and some of it is 3 digit value screws people up when they try to just read the instructions, once you see what it does to the car it becomes much clearer.

MaczPayne

iTrader: (5)

That was a very informative post, arghx, worthy of being added to the archives. I agree that most get confused at the 3 digit imperial display, I sure did at first. Initially I had also thought that Set Gain was a percentage value.

I have some values that might/ or might not be useful for other readers:

These values will almost always be different for each application. As stated above, it is best to obtain the boost curves while adjusting these values.

Set = 50% = 10psi
Gain = 15%
Set Gain = 90

Sandbagger

Maczpayne: I probably mis-read your post. If I read your last post correctly, your SET GAIN value of 90 means 9psi? right?

Archangels

Hey guys,

i've been playing with my profecB specII for a while now and cant find a happy medium when it come's to tuning it, i want to run 14.5-15psi constantly but all i can get is a constant 13psi that drops off in higher RPM and have the turbo spike to mid 15's....

these are my settings; ( In psi )

Boost: 63
Gain: 20%
Set Gain: 11.5
Warning: 15.8
WarningL: 20%

what settings do you guys use with your boost controller?, i like the quick response the gain gives, but something more stable would be nice, this is on a BNR3 turbo aswell....

Archangels

i should also mention, i still cant figure it out after reading this thread, i tuned the boost controller well enough in the first 3 gears however, in 4th and 5th the turbo spikes a fair bit, it spikes the same it did before but holds less boost....

i turned the set gain to 130 and the gain to 15%, i'm left here scratching my head, can anyone help?...

arghx

iTrader: (3)

I posted in your other thread