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Old 03-13-2013, 09:35 AM   #1
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Default Why is my Dashpot not working?

I posted this question on MSExtra and have been immensely diss-appointed in the lack of responses

As far as I can tell this looks like a bug to me - though it could just as readily be a tuning issue. For the life of me, if it is, I've absolutely no idea how to fix it.

I had hoped the devs might have taken a look at it, I'm not really sure how much more evidence - logs etc - I can post up.

Anyway I digress, here is my issue in a sort of copy/paste from MSEXTRA.

If anyone can offer any advise as to why this is happening I'd be most grateful:

Here is my car in Closed loop, the Idle PWM duty is 33.3


Here is my car about to enter an idle state, note that the Idle PWM duty is at 29.4, as you can see in the graph, this causes a nasty idle dip.


My dashpot is set at 3.9

33.9 - 29.4 = 3.9

Looks like my dashpot being subtracted and not added

My log and .msq are below, apologies in advance for the size of the log (13Mb) I tried to truncate it, but it just became unreadable.

Log
http://dl.dropbox.com/u/16897858/Meg...7_07.35.44.msl

.msq
http://dl.dropbox.com/u/16897858/Meg...7_08.47.41.msq

Then I upgraded to the latest 1.2 release code and changed PID activation to include VSS - so it wasn't accidentally driven down when not stationary and saw no change

Idle PWM is 29.8 VSS is 0, CL is active


Next set of lights, Idle PWM is slightly lower at 29.4, predictably there is an idle dip, where's the Dashpot adder gone? Surely the idle valve should be at 33.7%?!?


Another example


Note the dip isn't severe here, but still annoying, also look at the Idle valve before I come to a stop, it spikes and then drops it's value for no reason?


However, the dashpot does seem to work but only when you don't move the car, here is me blipping the throttle, the idle valve reacts as you'd expect.


Below are my current .msq and my log that the above images are taken from.

http://dl.dropbox.com/u/16897858/Meg...urrentTune.msq
http://dl.dropbox.com/u/16897858/Meg...8_07.38.16.msl

And finally today I managed to grab an SDCard log of the event



SDCard Datalog, look around the 155.576 timestamp
http://dl.dropbox.com/u/16897858/Meg...12_LOG0035.msl

Dashpot is not being added, or it is and then a whole chunk of duty is whacked off way before I get close to idle RPM's. Either way it's messing up my idle and I see no reason in my tune as to why it's happening.

TL : DR Why the chuffy chuff is Dashpot not being added in my tune?
Attached Thumbnails
Why is my Dashpot not working?-graph1.png   Why is my Dashpot not working?-graph2.png   Why is my Dashpot not working?-idle1.png   Why is my Dashpot not working?-idle2.png   Why is my Dashpot not working?-idle3.png  

Why is my Dashpot not working?-idle4.png   Why is my Dashpot not working?-works%2520when%2520blipping.png   Why is my Dashpot not working?-nodashpot.png  
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Old 03-13-2013, 10:04 AM   #2
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what firmware? I know there was an older ms2/ms3 firmware out there that it was broken for a while.

can you attach the msq here? i cant dropbox.
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Old 03-13-2013, 10:06 AM   #3
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This is something I also thought I would be experiencing for quite a while. Everytime I came to a red light or something like this the car will go into closed loop idle and drop instantly to the target idle. (and lower if lights, fan, etc. are on at this moment)

With the new "initial value table" I worked my way around this by adding some percent to my initial values, so that the starting point for the idle is a bit higher anyway...

I am also closely fooling your thread at msextra.com - hopefully James will take some time to look this up...

@Brain - I had this on all of the latest firmwares (also the alpha ones)

Here is a random screenshot - car going to idle - no adder whatsoever...

Attached Thumbnails
Why is my Dashpot not working?-idle_no_adder.jpg  
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Old 03-13-2013, 10:25 AM   #4
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The initial values table is a completely broken strategy. It will only work for a car without any additional on/off loads (such as headlights, cabin fan, defroster, etc).
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Old 03-13-2013, 10:32 AM   #5
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Quote:
Originally Posted by Braineack View Post
what firmware? I know there was an older ms2/ms3 firmware out there that it was broken for a while.

can you attach the msq here? i cant dropbox.
Latest 1.2 release for MS3

I've attached my .msq
Attached Files
File Type: msq CurrentTune.msq (176.0 KB, 104 views)
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Old 03-13-2013, 10:34 AM   #6
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Originally Posted by Zaphod View Post
This is something I also thought I would be experiencing for quite a while. Everytime I came to a red light or something like this the car will go into closed loop idle and drop instantly to the target idle. (and lower if lights, fan, etc. are on at this moment)

With the new "initial value table" I worked my way around this by adding some percent to my initial values, so that the starting point for the idle is a bit higher anyway...

I am also closely fooling your thread at msextra.com - hopefully James will take some time to look this up...

@Brain - I had this on all of the latest firmwares (also the alpha ones)

Here is a random screenshot - car going to idle - no adder whatsoever...

Zaphod, please post this on MSExtra, at least then I'm not a lone voice
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Old 03-13-2013, 10:34 AM   #7
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Quote:
The initial values table is a completely broken strategy. It will only work for a car without any additional on/off loads (such as headlights, cabin fan, defroster, etc).
I love the initial values table.

the voltage compenstation table should take care of the rest if you have shitty NA alternator.

it works much better, imho, than the last known value.
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Old 03-13-2013, 10:38 AM   #8
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Quote:
Originally Posted by Braineack View Post
I love the initial values table.

the voltage compenstation table should take care of the rest if you have shitty NA alternator.

it works much better, imho, than the last known value.
Voltage compensation does exactly zero, as on the 99-05 the alternator can keep the voltage stable above 650rpm or so, unless too many loads are added.
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Old 03-13-2013, 10:40 AM   #9
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Are you both using VSS to activate PID? try turning that off, I don't quite understand why you'd want to use VSS anyways, that means if you throw it in nuetral and cost, it wont control the idle valve so long as youre at speed, but it should.

I have a feeling that's what's causing it and something y8s ran into long ago.



Also, use idle RPM timing correction! Why would you have that off given the ability to run it? and idle ve?!
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Old 03-13-2013, 10:43 AM   #10
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I still don't understand why they haven't added support for clutch and neutral inputs for that reason.
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Old 03-13-2013, 10:44 AM   #11
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Quote:
Originally Posted by Reverant View Post
Voltage compensation does exactly zero, as on the 99-05 the alternator can keep the voltage stable above 650rpm or so, unless too many loads are added.
well that's why I said shitty NA alt. I much prefer intial values over last know. I dont have an issue when my fan is going (i dont even use adder with it on), or defroster, only the headlights and I've tuned the voltage curve to compensate for that.
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Old 03-13-2013, 10:46 AM   #12
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Quote:
Originally Posted by Braineack View Post
Are you both using VSS to activate PID? try turning that off, I don't quite understand why you'd want to use VSS anyways, that means if you throw it in nuetral and cost, it wont control the idle valve so long as youre at speed, but it should.

I have a feeling that's what's causing it and something y8s ran into long ago.

Also, use idle RPM timing correction! Why would you have that off given the ability to run it? and idle ve?!
Not using VSS to activate, using timing correction, using idle VE...
(P.S.: I have a very light 1.6 Fidanza flywheel if that matters...)

@richyvrlimited
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Originally Posted by richyvrlimited View Post
Zaphod, please post this on MSExtra, at least then I'm not a lone voice
Done!
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Old 03-13-2013, 10:46 AM   #13
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I still don't understand why they haven't added support for clutch and neutral inputs for that reason.
yeah dunno. I know Ken was aware, cause y8s complained about it a lot.

We both argeed that there should be idle control in nuetral when coasting, he disagreed. I believe y8s quickly stopped using the VSS PID activation feature when it was apparent it was more trouble than worth.




I'm on 1.2.0pro and dont believe I have the dashpot issue, only on like beta18-24 where it was broken. But I've only driven the car 30 seconds since I installed the ms3pro, but my dad would have complained of idle droop without the dashpot because it was pretty bad when the feature wasn't working.
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Old 03-13-2013, 10:49 AM   #14
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Quote:
Originally Posted by Braineack View Post
well that's why I said shitty NA alt. I much prefer intial values over last know. I dont have an issue when my fan is going (i dont even use adder with it on), or defroster, only the headlights and I've tuned the voltage curve to compensate for that.
In your case, you are lucky because the shitty alt causes the voltage dip, and the ECU compensates.
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Old 03-13-2013, 10:53 AM   #15
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lol. until I run my a/c and headlights at idle for too long and I drop to 10.5v and lose my LC1 input.
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Old 03-13-2013, 10:55 AM   #16
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Quote:
Originally Posted by Braineack View Post
Are you both using VSS to activate PID? try turning that off, I don't quite understand why you'd want to use VSS anyways, that means if you throw it in nuetral and cost, it wont control the idle valve so long as youre at speed, but it should.
Nope, read the OP (I'll let you off as it was a LONG OP ), I turned it on to see if I had a setting that was inadvertently driving the Idle PWM value down whilst I was driving. It's not that. It's off again now for the reason you state above.


Quote:
Also, use idle RPM timing correction! Why would you have that off given the ability to run it? and idle ve?!
That's largely irrelevant, and doesn't directly fix the issue. The dashpot should be adding which it's blatantly not doing. Fudging it is not fixing it

EDIT: If you look at the last SD card log the idle valve does weird ****. as soon as the throttle goes to below the threshold the idle valve PWM %increases and looks to include the dashpot. But only for a split second, and then it drops - massively - to some arbitrary number that bears no relation to a last known good value.

RE: the initial values table. That would be handy for me during warmup, (ignore my signature I have a coldside supercharger with no IC now which means IAT's rise quickly so unless I stop every 30 seconds the initial value is way off until the car is fully warmed up). After that it's as Rev says pretty useless.

@Zaphod, thanks!
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Old 03-13-2013, 10:57 AM   #17
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you expected me to read all that?!
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Old 03-13-2013, 11:04 AM   #18
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you expected me to read all that?!
No, I added the TL : DR just for you :P
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Old 03-13-2013, 11:13 AM   #19
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what happens if you make the dashpot -3.9?
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Old 03-13-2013, 11:20 AM   #20
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what happens if you make the dashpot -3.9?
Tried that, TunderStudio goes:

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