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Author Topic: Hanging revs and very jerky  (Read 18928 times)
Milka
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« on: June 19, 2013, 05:28:14 AM »

I'm having some issues with idle hanging sometimes.  This is not that big a problem by itself, but when I get off the throttle without disengaging the clutch revs will go to around 1250 rpm and if I'm on a flat or slight down slope revs will just start to jump up and down between 1250 and 1500, this is with my foot completely off throttle.  It only stops when I push the clutch idle will then sit around 1250 until the car really slows down and then it goes back down to normal 780 rpm.  Interesting thing is that it looks like throttle is actually opening and closing causing the jerkyiness?  I have been looking at the logs for ages and don't seem to be able to figure out what is causing this?  Intervention?   Idle PID?

Note the car is an RS6 converted to manual, twin plate clutch, GTX30 turbos

I originally thought I had a hardware issue, have now ruled that out after testing alternate Throttle body, Accel pedal, putting the N249 and stock DVs back in place, etc

Attached is a log with as many variables that I thought might be able to help.
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Rick
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« Reply #1 on: June 19, 2013, 05:33:20 AM »

Checked clutch switch is working?
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Milka
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« Reply #2 on: June 19, 2013, 05:47:49 AM »

Yeah seems to be working variable reads 0 during jerky behaviour then 1 when I push the clutch in and the oscillations stop but revs still hang until car gets really slow.
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Milka
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« Reply #3 on: June 22, 2013, 05:49:22 PM »

Just checked and the clutch switch it definitely working  B_kuppl is switching when clutch is pushed and is reading 0 doing WOT and during the time the revs are hanging and it's jerky
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Milka
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« Reply #4 on: June 22, 2013, 05:57:41 PM »

Ok so I have the hanging revs stopped.  Thanks PRJ!

But as the revs drop in the same place it's still very jerky.  From the logs there seems to be a lot of things oscillating, but I'm not sure which one is causing which....

 wdkba is oscillating even though wped is 0
 rl and rlsol are oscillating around each other? Could this be causing the ECU to open/close throttle?  Or is this just the result of the throttle oscillating?

Attached is new log
« Last Edit: June 23, 2013, 06:37:58 PM by Milka » Logged
prj
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« Reply #5 on: June 23, 2013, 07:36:59 AM »

i don't think this is the right log.
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Milka
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« Reply #6 on: June 23, 2013, 04:21:58 PM »

oops that was completely wrong, sorry.  Here is the correct log, accelerating, foot off accel pedal and then letting car coast back to idle speed.
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jibberjive
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« Reply #7 on: June 24, 2013, 09:33:43 PM »

Ok so I have the hanging revs stopped.
What was the solution?
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ddillenger
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« Reply #8 on: June 24, 2013, 09:41:52 PM »

What was the solution?

He had it posted, must have edited it?
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jibberjive
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« Reply #9 on: June 24, 2013, 10:16:10 PM »

I think I can glean from the title of his log what he did, but I had a similar issue on a previous setup, so I was hoping for a resolution/confirmation to the original post.
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ddillenger
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« Reply #10 on: June 24, 2013, 10:28:19 PM »

Something go lowered from 400 to 100 IIRC.
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Milka
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« Reply #11 on: June 24, 2013, 11:56:35 PM »

Hey guys sorry a little quick to say it was fixed, removed from post as it was not fixed and did not want to mislead

Tried again yesterday and still a problem on slight downhill (light load)Huh  Trying to figure out exactly which variables to log but most of them don't exist via ME7Logger and I don't know ASM c166 to figure out RAM locations.

Looks like mifa is causing milsol to oscillate is causing rlsol to oscillate, but really hard for me to log enough of MDFAW to figure out where is it coming from.

Thought it might be either intervention, torque reserves or idle PID, but as this is auto ecu converted to manual I'm sure there are a lot of differences due to Torque converter etc.  I really wish there was another 4.2 40v ECU that I could use that was originally manual with 2 MAFs.

If someone would be so kind as to assist with the XDF location etc for KFMIZUOF for my RS6 bin I could eliminate 1 of the possibilities.....
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Milka
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« Reply #12 on: June 25, 2013, 12:04:19 AM »

Oh if someone is kind enough to assist my bin is:

http://nefariousmotorsports.com/forum/index.php?topic=2645.0title=
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prj
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« Reply #13 on: June 25, 2013, 12:58:50 AM »

Most likely slow path idle pid still not quite what it should be.
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jibberjive
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« Reply #14 on: June 25, 2013, 02:11:57 AM »

Oh if someone is kind enough to assist my bin is:

http://nefariousmotorsports.com/forum/index.php?topic=2645.0title=

Is that your stock bin or your actual current bin?

BTW, I'm pretty sure my issue (with similar symptoms) was either torque reserve or idle PID, and not intervention.  Doesn't necessarily say much about your case though, just thought I'd throw that in there.
« Last Edit: June 25, 2013, 02:16:25 AM by jibberjive » Logged
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