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Old 06-26-2018, 01:50 PM   #2997
Ronnie_B
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Quote:
Originally Posted by thatspsychotic View Post
I'm for sure with you on the PID tuning issue, but (engineer here) I think it's due to too much derivative gain (and to a lesser extent integral gain) specifically... they're basically trying too hard to avoid overshoot. What I've consistently observed is that the boost will rise, then fall a bit little, then rise again to a bit higher level. This happens at pretty much any target boost level over 5 psi. At higher boost, it does oscillate, but it oscillates nearly entirely below the target boost level, which points to integral and derivative gain fighting each other.

More proportional gain, less integral (will help reduce overshoot) and especially less derivative gain to avoid the overdamped response.

The other thing that drives me bonkers is the low-speed response in 2nd and especially 1st gear. If you're rolling at say 10-15 mph and give some throttle input to maybe 30% throttle, you can watch the boost gauge fairly slowly go from vacuum to 0 psi to a little bit of boost even if you hold your foot completely still. This is a pretty unnerving sensation and makes you never really sure how much you're going to get for what you give in throttle input.

Definitely maddening. I'm hoping it'll clear up a bit with Stage 2 v2.4 which I'm headed to next week. Otherwise, Stratified it is.
I'm with you on the fact that the proportional gain and integral gain are fighting each other, creating the fluctuation in the process value. By gain, I meant integral gain being way too high, which is forcing the output up. The proportional gain may also need to be lowered, depending on how the loop responds to a lowered integral gain. Again, it's called "loop tuning" for a reason, so much of this will need to be tested.
What I do know is that these oscillations are classic symptom of an improperly tuned PID loop. I wish APR would listen to its customers, given we're engineers essentially offering free control system consulting advice on how to fix their issues.

I did notice a fairly significant improvement when going to Stage 2, and I'm really hoping that the issue doesn't start to creep back. The most maddening feeling is accelerating in 4th gear out of Turn 10 on the VIR Full Course, on the heels of an M3, and feeling the boost oscillate back and forth as the car in front pulls away.
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Old 06-26-2018, 02:09 PM   #2998
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Quote:
Originally Posted by Ronnie_B View Post
I wish APR would listen to its customers, given we're engineers essentially offering free control system consulting advice on how to fix their issues.
People have been complaining for well over a year now. They don't give a shit.
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Old 06-28-2018, 07:22 PM   #2999
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I checked a log. The strange situation, in the certain range of turns 3000-4000 for some reason opens N75 though having inflated corresponds to a request. Today I changed N249 and N75-the problem remained, also waves by sharp pressing with 3000 to 4000, everything is farther perfectly... What else to look at?
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Old 06-29-2018, 11:33 AM   #3000
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Quote:
Originally Posted by Dimbos666 View Post
I checked a log. The strange situation, in the certain range of turns 3000-4000 for some reason opens N75 though having inflated corresponds to a request. Today I changed N249 and N75-the problem remained, also waves by sharp pressing with 3000 to 4000, everything is farther perfectly... What else to look at?
Did you check/replace your PCV (N80)? Failed PCV could cause boost oscillations, but honestly it is probably the tune.
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Old 07-10-2018, 06:01 PM   #3001
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I'm stage II with version 1.2 now and am thinking about updating. From what I understand it should be ok with the Forge dv and catch can with pcv delete, but I could be wrong. I also have 02 sensor spacers, which I understand might cause a problem. Any advice?
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Old 11-14-2018, 04:17 PM   #3002
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Wow i have not checked this for a long time. Seems the issue i have on occasion seems to plague many.
Would love to see a resolution from APR. Would be nice considering the amount of money most of us have spent on their product.
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Old 11-14-2018, 06:19 PM   #3003
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If you have a problem, I'd suggest emailing our support team at support@goapr.com.

For what it's worth, recently our support team emailed every single customer reporting any sort of issues and asked them to try a new beta update. Only 2 customers responded, and neither of them ever flashed the file. Needless to say, we have nothing to flx / release / etc if we can't get confirmation anything has changed.
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Old 11-14-2018, 09:36 PM   #3004
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Quote:
Originally Posted by Arin@APR View Post
If you have a problem, I'd suggest emailing our support team at support@goapr.com.

For what it's worth, recently our support team emailed every single customer reporting any sort of issues and asked them to try a new beta update. Only 2 customers responded, and neither of them ever flashed the file. Needless to say, we have nothing to flx / release / etc if we can't get confirmation anything has changed.
I was one of the 2 customers who responded and have the beta file waiting at my APR dealer. There's a few different reasons why I haven't flashed yet:
1. The first week it was available I had a 2 day track event with Trackdaze at VIR, and I didn't feel comfortable thrashing on the car with a beta tune without testing on the street first.
2. I was rear-ended the following week and the car has been in the shop being repaired.
3. When I finally do get the car back and have it flashed, the verdict of whether it fixes the boost oscillation issue won't be immediately apparent. Unfortunately, the issue mainly occurs during warm / high humidity weather, so this time of year the car runs absolutely great. Part of me wants to wait until next year when I can take logs before and after the flash when I know the issue is occurring. This will allow me to provide immediate feedback on whether the beta file resolves the issue.

Anyway, that's probably more than you care to know, but it's my situation at the moment. Personally, I'm glad that APR continues to provide support for our tunes and is willing to make these types of tweaks and beta files available.
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Old 11-15-2018, 08:13 AM   #3005
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Anyway, that's probably more than you care to know, but it's my situation at the moment. Personally, I'm glad that APR continues to provide support for our tunes and is willing to make these types of tweaks and beta files available. [/quote]



This.


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Old 11-15-2018, 09:56 AM   #3006
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Thank you for the update Ronnie! I hope everything works out.
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Old 11-15-2018, 11:11 PM   #3007
Lazer 100
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Quote:
Originally Posted by Arin@APR View Post
If you have a problem, I'd suggest emailing our support team at support@goapr.com.

For what it's worth, recently our support team emailed every single customer reporting any sort of issues and asked them to try a new beta update. Only 2 customers responded, and neither of them ever flashed the file. Needless to say, we have nothing to flx / release / etc if we can't get confirmation anything has changed.


I donít remember seeing that email, but to be fair Iím not sure which email account I used when I originally had it flashed like 6 years ago. That being said, I got a stage II update back in August (was running the original stage II flash) and it has been waaaayyyyy better. Flatter torque curve. Seems like a boost increase maybe? Either way, Iím definitely satisfied. Havenít had any pulsating.


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