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Author Topic: Boost oscillation in higher gears - logs attached  (Read 8778 times)
untilnow
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« on: August 15, 2019, 07:21:57 AM »

I'm thinking this can be fixed using KFLDRL? (non stock exhaust)

This only happens in higher gears where it takes longer to climb up the revs.

Any suggestions?

...and yes, I know I'm pulling timing

Cheers guys

log link (wouldn't let me upload) -> http://s000.tinyupload.com/?file_id=05959996654525825869



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nyet
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« Reply #1 on: August 15, 2019, 07:33:43 AM »

Why are you taking a screenshot? Just use file->export.

Might want to dial back Q2
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« Reply #2 on: August 15, 2019, 07:43:50 AM »

Why are you taking a screenshot? Just use file->export.

Might want to dial back Q2

Thank you, I didnt know you could do that!  Shocked

I'll dial it back and re-log.

Any other suggestions?
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« Reply #3 on: August 21, 2019, 11:40:18 AM »

Just realised that I'm only overshooting on boost and not on load.

Its like boost and load de-sync at 3000 revs until 4000, see pics.


Whats causing this drop notch at 3500?  Huh

I was thinking of just filling KFLDRL with 90s after 3000 onwards as to force the correct flow by 'numbing' the PID?

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nyet
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« Reply #4 on: August 21, 2019, 12:45:32 PM »

Just realised that I'm only overshooting on boost and not on load.
The pid cares about boost, not load.

Quote
Its like boost and load de-sync at 3000 revs until 4000, see pics.

Whats causing this drop notch at 3500?  Huh
covered in the wiki. VVT

Quote
I was thinking of just filling KFLDRL with 90s after 3000 onwards as to force the correct flow by 'numbing' the PID?

No. You can reduce the slope of KFLDRL near the top (which would require increasing the slope elsewhere) but flattening it doesn't make much sense. If you are going to play DRL games, best to switch to IMX boost precontrol entirely.

Failing that, just numb Q2.
« Last Edit: August 21, 2019, 12:47:10 PM by nyet » Logged

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« Reply #5 on: August 21, 2019, 03:11:55 PM »

Okay, so the PID controls boost alone, I know there is ALOT of factors that controls the boost/load relationship so I'm not gonna go there just now. Grin

It had crossed my mind it could be the VVT causing the notch but the whole time fnwue≈0 (0.04 max) and intake cam shaft angle is only ever -/+ 1 away from 0 so surely it isn't VVT Huh
 
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« Reply #6 on: August 21, 2019, 03:21:07 PM »

Okay, so the PID controls boost alone, I know there is ALOT of factors that controls the boost/load relationship so I'm not gonna go there just now. Grin

It had crossed my mind it could be the VVT causing the notch but the whole time fnwue≈0 (0.04 max) and intake cam shaft angle is only ever -/+ 1 away from 0 so surely it isn't VVT Huh
 

There are other factors, you'd have to trace the FR to track them all down, but in general its IAT and VVT.
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« Reply #7 on: August 24, 2019, 03:19:39 PM »

Finally sorted it! Roll Eyes

This is my way of fixing it, a bit of a hack but safe if respected.

I just set everything in KFLDRL after 3750 (where oscillations start) to 90 (this is whatever waste gate u want for desired boost).
Because the linearization map is the final "filter" for the PIDs, you render every "PID" (WG) outcome to your given set values in KFLDRL, like an override  Grin

Kinda semi-open loop, let the PID deal with spool and peak boost then KFLDRLs control overrides the dumb PID.  Grin
Because of this I had to numb KFDLULS as I did throw a P1555 code = limp mode.

You have gotta be careful you don't mess up partial throttle so a good map blend and logging helps.

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« Reply #8 on: August 24, 2019, 04:02:28 PM »

It's not a fix. Youre totally ruined part throttle with that
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« Reply #9 on: August 24, 2019, 04:07:56 PM »

It's not a fix. Youre totally ruined part throttle with that

I never drive over 3500 in partial throttle and below that part of the map is stock.
« Last Edit: August 24, 2019, 04:16:37 PM by Tikki » Logged
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« Reply #10 on: August 24, 2019, 11:04:48 PM »

It's not a fix. Youre totally ruined part throttle with that

Not just that but he's ruined the entire point of the PID. altitude variance, temp variance, humidity variance... all of it will not be handled, and eventually he may throw a code.

Why not just numb Q2 like we told you to?
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« Reply #11 on: August 25, 2019, 04:02:43 AM »

Not just that but he's ruined the entire point of the PID. altitude variance, temp variance, humidity variance... all of it will not be handled, and eventually he may throw a code.

Why not just numb Q2 like we told you to?


Not ideal, I know lol  Grin I'll give it one last try messing with the PID, Q2, okay.
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prj
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« Reply #12 on: August 25, 2019, 04:11:11 AM »

dumb PID.  Grin

You are the dumb one, not the PID.
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« Reply #13 on: August 25, 2019, 03:52:32 PM »

You are the dumb one, not the PID.

Sorry mate didnt mean to offend any me7 purists out there.  Grin

PID tuning is testing at the best if times, just happy to have smooth power again.

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« Reply #14 on: August 26, 2019, 10:07:22 AM »

Sorry mate didnt mean to offend any me7 purists out there.  Grin

PID tuning is testing at the best if times, just happy to have smooth power again.

No, it is not "testing at the best of times".
That's the difference between copy-paste monkeys and people who understand how things work.

Someone who understands how the PID works can have it adjusted in 4-5 pulls. Someone who is a monkey that just mashes buttons can do it all day and get nowhere.
Goes without saying for a LOT of other concepts too.

Absolutely nothing to do with ME7 here. Just total lack of basic knowledge in control systems.
There are plenty of books and online resources that explain exactly how a PID works, how to tune it from scratch etc. Hell even the FR briefly explains it.

It's pure math.
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