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Old 06-17-2012, 10:08 PM   #1
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Default Retune boost PID after turbo swap?

I just took my car out for a spin with the new 2860RS. The previous turbo was an emotorUSA 2870.

I previously tuned the PID to hit 25psi, and it worked fine. I swapped turbos, and the log looks like it is only running on wastgate. 14psi can, but I saw 215kpa max. boost duty was 0 the whole time. Like a dummy, I didn't think to switch over to open loop and play around. It might be a day or two before I can take it for another run, so I figured I might as well see if anyone has experienced this before.
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Old 06-17-2012, 10:33 PM   #2
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A little more info:



Attached Files
File Type: msl 2012-06-17_18.57.26.msl (147.3 KB, 59 views)
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Old 06-18-2012, 10:17 AM   #3
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I thougt a while about this issue last night, and I think I know what it is. IIRC I had this same issue when I installed the china turbo. I think I have to tighten down the WG actuator rod some more. While it may seem tight enough to hold the WG shut, I think that there is enough slop to let it open a little under boost.
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Old 06-18-2012, 10:45 AM   #4
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you have WAYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY too much I.

your numbers should be in the low 20s for both P and I. also with that valve you should be using the 30Hz setting.


I would just go back to square one: start with 100 P, 0 I, 0 D. Lower P until you breech your target during spool. Increase I to keep that target to redline, increasing/decreasing P as needed. Add D as the last step to prevent overshoot and some oscilliation.
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Old 06-18-2012, 12:54 PM   #5
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Quote:
Originally Posted by Braineack View Post
you have WAYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY too much I.

your numbers should be in the low 20s for both P and I. also with that valve you should be using the 30Hz setting.


I would just go back to square one: start with 100 P, 0 I, 0 D. Lower P until you breech your target during spool. Increase I to keep that target to redline, increasing/decreasing P as needed. Add D as the last step to prevent overshoot and some oscilliation.
I remember us having this discussion when I was tuning the china turbo. The numbers didn't really make sense, but it worked very well. I do plan to go back and retune it. As I still agree with you, the numbers are whack. I've seen a few sets of PID values,a nd the truth is, they all seem to be around the same values P ~ 19 or 20, I under 20, and D is 10 or less.

I think in my effort to spool as quickly as possible I was able to get my P value down to 12, but it required the extremely high I an D values to maintain target.


PS Thanks for the tips brain. I do appreciate them!

On a bright note, the new turbo felt as strong at 16psi as the china turbo at 25psi. Butt dyno of course, but I'll probably run the 2860rs to 22 psi.
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Old 06-18-2012, 02:12 PM   #6
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nice. for boost I'm like P27 I27 D75.


I wont help with spool, that's long term tracking. Lower P will, but it will also overshoot. increasing D with dampen the overshoot at exspense of some responce.

When all is said and done, you'll see like a 1-2psi overshoot at spool but hold the target all the way to redline perfectly smooth.
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Old 06-20-2012, 11:05 PM   #7
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I had to lower my P value to 1 before it would boost 2psi over target (25psi) So far mar PID values are 1,0,0 lol. I'm sure I'll have to increase P as I increase I. A P value of 12 only got me to 15psi. Trying to do a boost log in 5th gear from 2000rpm makes my turbo feel like ----. It doesn't come alive until 3500rpm.
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Old 06-21-2012, 04:23 AM   #8
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Not sure this is correct what you are seeing... Is your plumbing o.k.?
Did you try the open loop?
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Old 06-21-2012, 09:57 AM   #9
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Quote:
Originally Posted by Zaphod View Post
Not sure this is correct what you are seeing... Is your plumbing o.k.?
Did you try the open loop?
I haven't messed with open loop for the new turbo. It was tuned for the previous turbo. The EBC appears to be doing its job. iirc my last turbo required the I to be raised before it spooled to my liking. I have a feeling that I will have to increase P as while I'm increasing I. If I don't have success, then I'll go to open loop. I did some research on the spool of this turbo with the .86 housing, and it doesn't seem like 23psi at 4300rpm is that bad. It's a dog in 5th witht he 3.636 before 3500rpm.
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Old 06-21-2012, 10:25 AM   #10
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Have u tried increasing the frequncy to 30hz and intrvals to 10ms?
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Old 06-21-2012, 10:41 AM   #11
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My interval is still at 23ms, but I did change to the 39Hz option. I don't believe I have a 30Hz option. I'm going to look at this mornings logs. I took two runs on the way to work with I set to 5 and then 10 with P still set to 1. Based on the gauge reading with I=10 it looked very close to target. Should I be doing the boost tuning in 1:1 gear?
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Old 06-21-2012, 10:46 AM   #12
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doesn't matter. I like to tune p in low gear to just set the target at spool and the rest on the highway in 4th and 5th
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