When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
close to the "basic" settings which I believe is 100 and slider 60-80.
8kpa overshoot every now and then should actually be fine on a basic iwg setup, you should not be worried about that. even some of the most advanced setups still vary by 8kpa/1psi
the efr setups are different from the above though.
Reducing the Max DC% was a pretty big revelation for me. I don't think I've ever had a car get to target and not overshoot as well as this one. I will datalog some street stabs but on the dyno it was flawless. This is a 8-second pull from 2000 to 7000 on a Dynapack. Car makes 195kpa on the can, targeting 220kpa.
Andrew,
Very good info thank you. Did you try 100% and 55% and notice any difference?
My main concern being: the whole reason we use EBC is for it's ability to stay closed till the very last second, I wonder if spool difference is noticeable between 100 and 55
Andrew,
Very good info thank you. Did you try 100% and 55% and notice any difference?
My main concern being: the whole reason we use EBC is for it's ability to stay closed till the very last second, I wonder if spool difference is noticeable between 100 and 55
I can give it a shot but if my memory serves, it just caused massive overshoot because the algorithm can't move from 100% to the 45% target fast enough.
I overcame that by basically playing with the bias table and moving the rpm point where it switches from 100 to 45-50%, but I see what you're saying, and I bet in reality it achieves the same thing and has similar/same onset
Reducing the Max DC% was a pretty big revelation for me.
QFT..
Vlad. Somewhere before 100% DC the valve is effectively closed. On my setup I saw no difference in spool between 60% and 100% duty cycle. It was the same as if the valve was closed. Same with minimum. Slowly bring the minimum up and see where you get an increase in boost.
Limiting the algorithm to the actual effective range will make a huge difference in how hard the algorithm has to work. Imagine if your throttle pedal only worked from 20-60%, and you were trying to control engine output.
I would go out tonight and show you. But my turbosmart IWG sharted all over my turbo, and my data will be useless.
But here are some logs from my old 1.6 setup.
100% Duty Cycle 198.8kpa at 4409rpm
60% Duty Cycle. 198.5kpa at 4383rpm
As you can see they are basically identical. The 60% actually reached 198kpa sooner, but 30rpm is within measurement error.
These logs were on the same stretch of road. Logs are attached.
I overcame that by basically playing with the bias table and moving the rpm point where it switches from 100 to 45-50%, but I see what you're saying, and I bet in reality it achieves the same thing and has similar/same onset
This wont have the same effect. Because if you are in 6th gear, or going uphill, or the weather changes, or anything that causes the switchover point to be a different RPM, you wont be at the ideal duty cycle. By limiting the maximum to the actual maximum you make it easier on the algorithm.
We test/check/set up the range for each valve before dialing in boost control.
Some are like yours with a narrow range, some are really broad. At least 2 I've done so far the range was something like 10-90.
As for weather/load, we tested all that and did not get any significant overshoot in varying conditions.
I'm not disagreeing with what either of you are saying/doing, I'm actually just curious if your approach is better than mine (it probably is, and even if not it's still probably the safer approach).
I'm gonna try your approach on Sean's car and compare.
*edit: also above screenshots don't include boost duty lol. I'll open the logs when I get home
Check out this table (I couldn't find a real source, but this is where it came from. I'm sure a MAC catalog has it somewhere) from - Boost solenoids
If you are running 19Hz on a 3 port valve (which I think you should be) then you are looking at 15-86 approx. And this is just the range that it lets air through. You get up near the top and its letting so little air through that its not going to do anything. Its just a restriction. Boost on one side, valve in the middle, less boost on the other.
Andrew, what happened when you used a smaller value for lower limit delta? Did it cause overboost and/or oscillations for you?
Asking because in my tests I had found that getting this value lower generally helped with spool unless it was so small that the PID algorithm struggled to kick in and control things.
That's a cool chart Aidan. I just upped my max duty cycle to 90 and didn't see any crazy changes in the PID trying to compensate. I might roll back to 70-80 and see if that changes spool up at all.
*edit: also above screenshots don't include boost duty lol. I'll open the logs when I get home
They are open loop. 60% all the way across and 100% all the way across.
This will always be setup dependent. And probably have lots of other variables.
And if you find a way that works for you by all means do it. And teach us about it. I'm just giving some background on how the algorithm and mechanics work.
I am probably about to demonstrate a lack of understanding, but here it goes.
It appears common to have issues with the Integral values that work pretty well on quick applications of throttle causing overshoot on longer pulls.
Where this is a problem is that the Integral term will typically have a larger contribution on a long pull where we are within our delta a while.
Once the boost target is hit, that larger Integral term value persists and only slowly reduces its contribution as time goes by. It seems like once target boost level is attained, a reset of some sort would be in order. At least a reset of the inflated Integral values, since we are no longer the same time spent away from the target boost level. In the shot below, Integral was still 4.5 at throttle lift, down from the max of 7.1.
Time spent inside delta to target boost was one second. Time till throttle lift was 1.6 seconds
The values that result in the screenshot above cause MAP to sit a few kpa below target boost on a second gear pull (it would reach, but who stays in second for long), and to have a small bump/dip on the third gear pull. Maximum deviation is less than 10 kpa, so I'm relatively satisfied with these settings.
Just searching for a better understanding.
Thanks.
Not too change the subject, but how exactly does the boost by gear feature work? Is it just a cap and the desired boost table still in play? Or does that get bypassed?
Second question, I see a table switch based on gear but it's greyed out, how do you enable it?
I just want to kill a few psi in first gear and use the desired boost table in 2-6 gears.
These settings overshot a bunch on the street. I started by going back to 100/100/100 and turning the slider down to 120. Less overshoot, so I backed the slider down to 75 and turned the duty down. No more overshoot, but it was stabilizing in the 230kpa range. Backed the duty off a bit more and got to this. I think I'm done messing with it.
You could possibly set a boost by gear up using the boost by wheel speed settings and choosing set wheel speed points where you change gears. It's not the most ideal way to do it depending on what you want to do since there isn't really enough resolution. Benefit of it is though that it only uses the VSS target boost when above a certain throttle position so you can still use the target table for anything lower than full throttle.
Something like this.
These settings overshot a bunch on the street. I started by going back to 100/100/100 and turning the slider down to 120. Less overshoot, so I backed the slider down to 75 and turned the duty down. No more overshoot, but it was stabilizing in the 230kpa range. Backed the duty off a bit more and got to this. I think I'm done messing with it.
Have you guys run your settings at different ambient temps? I've been happy with my new settings, until a couple nights ago I went out when it wasn't obnoxiously hot and humid (like 80 degrees instead of 95) and picked up 10kpa pretty much across the pull. The EBC was dropping duty cycle, but it still wasn't doing enough. I feel like I'm going to be back to starting over in a few months when it cools down.
Maybe it's time for me to dive into Advanced mode.
09-20-2017, 08:11 PM
0
