Messing with Waste Gate Controls

[silverbullet08]

Finally downloaded the LNF update! looks pretty snazy lol. Dont have much to do today so im about to go test a few things out on the wastegate control and desired boost tables.

[silverbullet08]

Results:
After tinkering with the tables adding a little here and there, i wasnt seeing any changes. I went ahead and maxed out the duty cycle correction table and set duty cycle maxto 100% "it will actually go to 327.68%" to see if i could hold boost a little longer. Results were 255kpa till 5,100rpms. Dropped to 235-230kpa at 6200 and i let out. I do still have the WG rod adjusted.
Im not sure how far you can push these tables though so im gunna wait for someone else to post up thier thoughts. Id like to get it to hold 23psi till red line lol but not sure how well the turbo will like that.

[Terminator2]

Same here I am going to loosen my wg rod back close to stock now though. Dont want to be spiking 30 psi when tuning for 24 psi LOL.

[fr0stb1t3]

Try the Proportional Max table and let me know how it goes. There are some interesting differences between the stock and GMPP tune.

[BackyardTurbo_FTW]

You dont need to mess with those really, the WG Correction Table works nicely

[silverbullet08]

You dont need to mess with those really, the WG Correction Table works nicely

Yea I stopped at 100 on the WG correction table but noticed it would go up to 327.7. Wasnt sure how far we could push that table yet. I use to run my DAL table at 279 then after 5000 bumped it up to 300, it helped by like 1 psi but i moved it to a flat 279 all the way through.

[BackyardTurbo_FTW]

The WG% wont go over 100 so going to 300+ wont be doing anything different.

[rnjmur]

So a question for those messing with the WG duty...

1. Does the WG cor factor table make its cor from the max WG % (i.e. (Max = 95 * cor = 95) = 90.25%

or

2. Does the WG cor factor table set the WG % up to the max WG % (i.e. (cor = 95, max = 95) = 95%

The Proportional Max table seems to max at 90.025% which may support #1, or maybe I am reading into the numbers too much....

[gmtech16450yz]

So a question for those messing with the WG duty...

1. Does the WG cor factor table make its cor from the max WG % (i.e. (Max = 95 * cor = 95) = 90.25%

or

2. Does the WG cor factor table set the WG % up to the max WG % (i.e. (cor = 95, max = 95) = 95%

The Proportional Max table seems to max at 90.025% which may support #1, or maybe I am reading into the numbers too much....

I've literally had just a little bit of time tonight to play with these tables, but I believe #2 is correct. I left max at 95%, when correction table is at 100%, desired DC in the logs will show 95% since max is only 95%. When correction is at 70%, DC in logs is showing 70%. At least that's what it seemed like but I've only loaded 1 tune so far! Next tune I'm hoping for a nice, flat boost log!

BTW, you're never gonna get a stock turbo to boost 23lbs to redline no matter what you put the wastegate tables at. It just can't do it, or better yet, be made to try. (At least in my experience.)

[Chris@HPTuners]

the WG correction table takes the calculated WG DC% for the PID controller (the prop, int, deriv stuff) and maps it to the final WG DC%, it is a direct mapping, not an adder or multiplier or anything like that.

The DC Max is the last thing checked so it is *after* the WG correction table.

Chris...

[rnjmur]

the WG correction table takes the calculated WG DC% for the PID controller (the prop, int, deriv stuff) and maps it to the final WG DC%, it is a direct mapping, not an adder or multiplier or anything like that.

The DC Max is the last thing checked so it is *after* the WG correction table.

Chris...

I've literally had just a little bit of time tonight to play with these tables, but I believe #2 is correct. I left max at 95%, when correction table is at 100%, desired DC in the logs will show 95% since max is only 95%. When correction is at 70%, DC in logs is showing 70%. At least that's what it seemed like but I've only loaded 1 tune so far! Next tune I'm hoping for a nice, flat boost log!

BTW, you're never gonna get a stock turbo to boost 23lbs to redline no matter what you put the wastegate tables at. It just can't do it, or better yet, be made to try. (At least in my experience.)

Sounds good, thanks guys!

I have looked over the turbo compressor maps and after about 28 lb/m at 23 psi (the k04 max) the turbo runs out of steam (which is about 4K - 4.5K rpm) and pressure will start to drop off no matter what you do. Playing with the WG DC you might be able to help hold pressure above this, but the compressor is simply maxed out. After about 6K the turbo really hits a brick wall.

[T-Man]

Here's something I stumbled upon while searching how the PID Controller workers with regard to boost. Pretty good read and I plan to try and utilize this to some extent because looking at the GMS1 tune for the cobalt, most of the changes made were in P and D with I having minor changes.

"In control loops P is most of your control, with I helping, but Derivitive is seldom used especially on a simple loop. Proportional is the gain the loop is using whereas the Integral is sets per minute. It would be like being the cruise control in your car where set point is 80mph. The gas pedal and how far you pressed it would be the P or gain and how often you pressed the pedal to the desired gain would be you Integral or sets/min. Have you tried to tune the loop using just P?

Proportional depends only on the error signal or the difference between set point and process variable. More P will in general increase the speed of the control process, but if proportional gain gets to large the process variable will begin to oscilate and as gain is increased the system will become unstable.

I would set the I and D to zero and increase P until you begin to oscillate, but the speed of the control loop is sufficient or untill you become unstable. Once you begin to oscillate then I can be introduced to stop the ocillations. More I will reduce steady state error or in other words when the loop settles in the set point and process variable will be closer, but you will pay a price of more overshoot. You will always have some overshoot which is nessessary if your control loop is going to be fast enough to respond to changes immediately. Once P and I have been set to get the desired fast control system, D can be introduced until the loop is acceptably quick to setpoint. D will decrease overshoot and gains can be higher with more stability, but more D will make the system highly sensitive to noise in the process variable and will quite often make the system unstable which is why D is left out of the PID loop often."

Edit - Attached is another supporting document I found

[gmtech16450yz]

Sounds right to me T-Man, good cruise control analogy.

PID controllers are getting more and more common, I learned (was forced to learn) about how it works when trying to nail down idle problems in E38's. Looking at the big picture and oversimplifying it, if your desired whatever (boost, idle, fuel pressure, injection, throttle angle, whatever is being controlled) is matching your actual, I don't think you really need to mess with the control side of it. The little I've looked at the boost control it looked like it was following commanded pretty closely so far. In theory what you might gain is a little faster spool but then overshoot would be hard to control. Everything on these LNF's seem to be sensitive to big changes, so smooth control of boost, ign timing, cam timing, fueling, throttle, etc seems to be the best approach.

[Iam Broke]

Hi all,

I wrote entire my file over the TF combo today, so far I got the fueling ok, but I'm aftraid I havent found the key to holding WG DC% up to 95% like the layer file tune did. Tapered off up top down to 72% with DAL's through the roof, the GMS1 turbo protection still seems to be there. I'll take a few screen shots for a starting point and post back shortly. Damn cat warmup mode is back also.

[Iam Broke]

You can see from this screen shot the Boost Control Duty Cycle is tapering off up top.

The Combo tune will hold 95% WG DC all the way out.

[gmtech16450yz]

Hey Tom, look at my other post, it can be made to hold 95% solid. I'm gonna put together a new thread to keep all our thoughts in one place... be right back.

[Iam Broke]

Here's some caps of the Inj angles & fueling I'm playing with, pulls strong, just the boost is tapering off again.

FYI on the fueling, 15 MPa is 2175 psi, I'm currently on E60 BTW.

[Iam Broke]

Hey Tom, look at my other post, it can be made to hold 95% solid. I'm gonna put together a new thread to keep all our thoughts in one place... be right back.

I think I found it in the Proportional Max table, I also changed the header at the top of the table so that 165 = 23.9 psi in the highest column for those of us seeking 24 psi.

[gmtech16450yz]

http://www.hptuners.com/forum/showthread.php?t=33473

[silverbullet08]

I think I found it in the Proportional Max table, I also changed the header at the top of the table so that 165 = 23.9 psi in the highest column for those of us seeking 24 psi.

So are the tables you posted up the ones your using to try and reach full e85? Im currently on 60%E also. I didnt mess with the FP or any of the injector windows yet. My WG tables look exactly the same as yours lol. I noticed a 24-25ish spike holds till 5000 on the dot then drops very quickly to about 21psi then slowly tapers to about 19psi. Occasionally though it will just take it and hold about 22psi till redline? Im not sure why but during the whole pull it feels alot stronger than normal. When it first did this The car cut throttle and fuel completely? just shut down then a split second later pulls again? I noticed it on the logger that AFR went to 1.00 timing stayed flat lined 24* cams followed thier normal pull... It lights the tires up hard though at 70mph when it does this. Not sure what caused it....