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I don’t filter and mine damn near lay on top of each other. I run map control though, which you can after your dome is close. With Humphrey solenoids my dome is 14/30/0.5 and map is 0.7/2/0.
I would like to switch to that setup eventually also. I definitely have some adjustments to make, but at least now I know what I have to do.
Yes. I have been worried to make too many changes in fear of screwing something up, but I am just going to have to try things and see the results so I know what cause and effect it has. That is why I love the idea of using shop air to get closer on my settings. I can't hurt anything and can always go back if I went the wrong way.
Yes. I have been worried to make too many changes in fear of screwing something up, but I am just going to have to try things and see the results so I know what cause and effect it has. That is why I love the idea of using shop air to get closer on my settings. I can't hurt anything and can always go back if I went the wrong way.
Youll absolutely love the shop air set up. The whole test is “cause and effect.” That’s what most of us car guys strive for, understanding what does what. Remember to adjust the target rate limiter also. It makes a difference. I think mine’s at 60.
Took my time with the shop air PID tuning and ended up with 4/14/0. The dotted line is 1st gear from my last pass at the track. Looks a LOT better to me except the only thing I can't seem to get rid of is the dip right after I release the TB button. I am set to 30 target on the button and 20 on the time vs. boost. I will be making some passes today so I can see what a real world pass to pass overlay looks like.
I turned the target rate limiter down to 60. Here is a log of my last full pass. Boost curve looks MUCH better. I was surprised to see the dome pressure was still bouncing from 22si to 18psi. Is that normal or do I need more tuning on the PID's? Car ran smoothe down the track. Shook the tires for a second right where the boost spiked on the ramp up.
I’d say your really close. There’s going to be a variation because the solenoids are cycling trying to maintain your target dome pressure. Think of it almost like an average/median. Only thing is the more dialed in the PIDs are, the less swing it’ll have. For example, the halfway point from 0 and 100 is 50, the halfway point from 49 and 51 is also 50. Make sense? How much does the actual boost swing over the pass?
I’d say your really close. There’s going to be a variation because the solenoids are cycling trying to maintain your target dome pressure. Think of it almost like an average/median. Only thing is the more dialed in the PIDs are, the less swing it’ll have. For example, the halfway point from 0 and 100 is 50, the halfway point from 49 and 51 is also 50. Make sense? How much does the actual boost swing over the pass?
Yes that does make sense. Not sure if I should mess with it more or just leave it since it seems to be running smooth down the track now.
Other than the dip down to 20.6 that came right after the small spike to 21.4 where it shook the tires, the rest of the pass was a low of 21psi that I marked and a high in the top of first gear to 22.9. Not sure why it never seems to make max boost until the end of the 1/4 unless the turbos aren't fully spooled with my little 388ci?
Thank you guys. Taking baby steps on the launch. Been 1.29 but first pass Saturday she was going airborne and had to abort. Last thing I want to do is stand it up and come crashing down!
Bringing this back from the dead with potential new information found since the issue never really went away.
To make a long story short, when I got my two new wastegates they had 2 springs with them. When I laid them out, there was an all silver spring, a mostly spring with red overspray on it, a mostly black spring with a little red showing through, and a silver spring with a lot of black on it. I chose the two mostly black springs.
Fast forward to 2022, I take the wastegates apart to put the lighter springs in and remembered they were all different colors, so I took out my calipers and measured them. (Not sure if I had bought them yet when I first built the car). The two springs I was running all those seasons were mismatched. One was .210 and the other was .260 diameter! I measured the other two in the box and they were the matching .210 and .260.
Not sure if that was causing this issue, but I am sure it must have been driving the boost controller and turbos crazy. Car isn't back together yet, but looking forward to seeing how much matched springs made a difference in the graph.
Nice to see good technical discussion on PID control in here. I've struggled lately learning PID control on a closed loop boost control system, but its cool stuff!
09-12-2018, 09:34 PM
