Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

KR when shifting

Old Mar 29, 2004 | 04:03 PM
  #1  
96zvert's Avatar
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From: Lebanon, Ohio USA
KR when shifting

I seem to be getting about 6 degrees of KR when shifting gears
on my car it shows up after I let off the gas and switch gears,
and is there till it is gradually pulled out through the next gear, and then happens again when i shift to the next gear. This only happens on WOT runs. Not sure how to fix this problem. Anyone have any ideas?
Old Mar 29, 2004 | 06:14 PM
  #2  
JeffK95Z's Avatar
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From: Vancouver BC, Canada
Its nothing to worry about, and very common...

I can't remember the exact reason, but i believe it has to do with the sudden change in MAP as you let off the gas...

there MAY be a table you can edit to turn this off, but hopefully someone else will chime in with info...

Either way, its not real knock and just about everyone with M6's (i have no idea about A4's, but i wouldn't think they would have a pressure drop on gear changes?) will encounter this knock...

jeff
Old Mar 29, 2004 | 06:28 PM
  #3  
96zvert's Avatar
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I thought it was false knock too, but wasn't entirely sure. Is there a way to eliminate it, or do I just tune it out?

What bothers me, is that it takes nearly the whole next gear to get full timing back in , and then as soon as I shift, it pulls 6 degrees again. Should I just modify the Knock Retard Recovery Rate so the timing comes back in quicker?
Old Mar 29, 2004 | 09:35 PM
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From: Mukilteo, WA
That sounds like Burst Knock. There are a couple values (temp, % MAP) in the ECM constants list of Tunercat that will disable it if you put them to maximum.

I did this after realizing the knock count wasn't going up when I was seeing the retard and it eliminated it. Then I got real knock (it didn't happen right when going to WOT but a little after, and knock count went up)...pulled a couple of degrees of timing until that went away too. Now, zero knock. Ever. Running a couple of degrees less base timing is better than running with 6 or more taken out.
Old Mar 31, 2004 | 05:04 PM
  #5  
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it is the sudden change in the map pressure. you can tune it out or completely turn it off buy zeroing the table out. it wont hurt anyhting thing. the reason it takes so long to put the timing back is because the pcm is set to a certain rate to put it back in, but you can change that to.
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