stuklr
Full Member
Karma: +2/-0
 Offline
Posts: 146
|
 |
« on: April 22, 2014, 07:20:25 PM »
|
|
|
I have the PID pretty well dialed in as far as on road impressions, but wanted a couple of second/third opinions. The hardware is 60lb EV14's and frankenturbos on an 01 Allroad. Stock wastegate actuators. I have some ignition correction, but I am only running a single meth nozzle. Waiting on my two matched nozzles to get here before I finish timing.
|
|
|
|
|
Logged
|
|
|
|
|
nyet
|
|
« Reply #1 on: April 22, 2014, 08:06:25 PM »
|
|
|
Your wg duty is a mess.
Why isn't it 100% during spool?
You are leaving a TON of torque on the table.
|
|
|
|
|
Logged
|
|
|
|
|
nyet
|
|
« Reply #2 on: April 22, 2014, 08:09:59 PM »
|
|
|
Why did you disable P?
Also, your I-Max is a mess.
|
|
|
|
« Last Edit: April 22, 2014, 08:11:38 PM by nyet »
|
Logged
|
|
|
|
stuklr
Full Member
Karma: +2/-0
Offline
Posts: 146
|
|
« Reply #3 on: April 22, 2014, 09:02:22 PM »
|
|
|
Nyet, Can you explain what you mean by "Disable P"?
My whole reason for making changes to the PID were that the frankens use a lot of spring preload and the gate openings seem to be undersized. I was getting a lot of overshoot initially.
My initial response was to drop the P (LDRQ0S to 1.8 from 2.0) and I (LDRQ1DY 20% drop above 2750rpm) terms to slow boost build and lower my IMX to keep the spike at bay. Those changes and increasing Q2 made a world of difference. I also followed what has been posted to set KFLDRL to match the DC response. Not sure I used the spreadsheet PRJ posted correctly though.
It has worked. Boost may build a little slower, but it only does what I request. Killed the overshoot.
I do see that my WGDC is crazy on spool, but a little more stable once boost is built.
My approach may not be as aggressive as you usually set cars up. Its my daily and has a baby seat in the back.
I really appreciate your help. I have read a lot on different PID approaches for ME7, but there are limited examples out there to compare notes with. What would you recommend?
I like strong bottom end TQ( I miss the hit of my K03's a little), but don't want to get too aggressive and make the car an on/off switch or stress the rods.
Either way, Thanks for any and all comments. No better way to learn than with feedback.
|
|
|
|
|
Logged
|
|
|
|
|
userpike
|
|
« Reply #4 on: April 22, 2014, 09:07:18 PM »
|
|
|
|
|
|
|
|
Logged
|
|
|
|
stuklr
Full Member
Karma: +2/-0
Offline
Posts: 146
|
|
« Reply #5 on: April 22, 2014, 09:45:26 PM »
|
|
|
Excellent Video. I am 2/3 of the way through it and have already made some revisions I will try on my morning commute. It also stresses the need for proper DRL tuning. I think I will go back through that. Thanks for posting that link.
|
|
|
|
|
Logged
|
|
|
|
|
nyet
|
|
« Reply #6 on: April 22, 2014, 10:02:34 PM »
|
|
|
Your P contribution is zero in the log you posted.
You should be at 100% DC during spool, and use Q2 and an appropriate i-limit (preferably a relatively smooth one) to prevent spikes.
The way to limit torque is NOT by screwing up the PID control, but to have less req torque... and no, I don't see a good reason to do that either.
|
|
|
|
« Last Edit: April 22, 2014, 10:07:08 PM by nyet »
|
Logged
|
|
|
|
|
userpike
|
|
« Reply #7 on: April 22, 2014, 10:45:43 PM »
|
|
|
Excellent Video. I am 2/3 of the way through it and have already made some revisions I will try on my morning commute. It also stresses the need for proper DRL tuning. I think I will go back through that. Thanks for posting that link.
no problem! it helped make alot of sense out of confusion for me. tune P, D then I.. now I understand why.  |
|
|
|
|
Logged
|
|
|
|
|
littco
|
|
« Reply #8 on: April 24, 2014, 02:54:32 PM »
|
|
|
Your P contribution is zero in the log you posted.
You should be at 100% DC during spool, and use Q2 and an appropriate i-limit (preferably a relatively smooth one) to prevent spikes.
The way to limit torque is NOT by screwing up the PID control, but to have less req torque... and no, I don't see a good reason to do that either.
One thing.. With 100dc you divert boost away , thus creating a "boost leak" as the boost is drawn away from the charge system... 0dc obviously flows boost to actuator but allows waste gate to open.. Have you tried a valve on the charge side of the n75 set to crack at 15psi (or similar) to limit boost loss on spool? |
|
|
|
|
Logged
|
|
|
|
|
nyet
|
|
« Reply #9 on: April 24, 2014, 04:05:40 PM »
|
|
|
One thing.. With 100dc you divert boost away , thus creating a "boost leak" as the boost is drawn away from the charge system... 0dc obviously flows boost to actuator but allows waste gate to open.. Have you tried a valve on the charge side of the n75 set to crack at 15psi (or similar) to limit boost loss on spool?
Interesting point... never thought about this. Is that leak really significant? I've never noticed that it was. |
|
|
|
|
Logged
|
|
|
|
stuklr
Full Member
Karma: +2/-0
Offline
Posts: 146
|
|
« Reply #10 on: April 24, 2014, 04:14:30 PM »
|
|
|
Its not a leak to atmosphere. Just back into the spider hose assembly.
|
|
|
|
|
Logged
|
|
|
|
|
phila_dot
|
|
« Reply #11 on: April 24, 2014, 04:47:59 PM »
|
|
|
One thing.. With 100dc you divert boost away , thus creating a "boost leak" as the boost is drawn away from the charge system... 0dc obviously flows boost to actuator but allows waste gate to open.. Have you tried a valve on the charge side of the n75 set to crack at 15psi (or similar) to limit boost loss on spool?
You're describing an MBC in parallel. The amount of air routed from the compressor housing into the spider is inconsequential IMO. |
|
|
|
|
Logged
|
|
|
|
|
AARDQ
|
|
« Reply #12 on: April 24, 2014, 04:54:30 PM »
|
|
|
Nyet, Can you explain what you mean by "Disable P"?
My whole reason for making changes to the PID were that the frankens use a lot of spring preload and the gate openings seem to be undersized. I was getting a lot of overshoot initially.
I have pretty much the same set-up as you same set-up (A6, not AR, though) and made things much smoother by decreasing WG spring tension to 7 or 8 lbs opening pressure and linearized KFPED in the region where boost comes on. Not having the throttle snap full-open at 40% pedal (or whatever) was key. I'm sure there are other ways to do this also. |
|
|
|
|
Logged
|
|
|
|
|
catbed
|
|
« Reply #13 on: April 24, 2014, 06:03:16 PM »
|
|
|
One thing.. With 100dc you divert boost away , thus creating a "boost leak" as the boost is drawn away from the charge system... 0dc obviously flows boost to actuator but allows waste gate to open.. Have you tried a valve on the charge side of the n75 set to crack at 15psi (or similar) to limit boost loss on spool?
I set my WGDC to 0% until close to wastegate pressure for the exact reason you said. I'm sure it doesn't matter that much, just a matter of personal preference. |
|
|
|
|
Logged
|
|
|
|
stuklr
Full Member
Karma: +2/-0
Offline
Posts: 146
|
|
« Reply #14 on: April 24, 2014, 06:10:37 PM »
|
|
|
I have pretty much the same set-up as you same set-up (A6, not AR, though) and made things much smoother by decreasing WG spring tension to 7 or 8 lbs opening pressure and linearized KFPED in the region where boost comes on. Not having the throttle snap full-open at 40% pedal (or whatever) was key. I'm sure there are other ways to do this also.
Problem with that approach is it reduces the spring's ability to keep the gate sealed at high boost levels. Lots of pressure build up in the small turbine housings. |
|
|
|
|
Logged
|
|
|
|
|
