"Idle learn limits"

[efizjb]

Are there any negatives to increasing the values both positive and negative? I've done a lot of research here and used the idle tuning tutitorials. In my searches I've found only a "couple" mentions relative to changing the learn limits.

I'm assuming it can only help widening these limits on a heads/cam car. However are their any negatives to doing this, or making them too big which would have a negative impact on the idle overall? As there's so little mention of it should they not be touched?

[WeathermanShawn]

I have not played around with the Idle Learn Limits or Idle Airflow Corrections as much as SSpdDmon http:////forum.efilive.com/showthread.php?t=4661 (http://forum.efilive.com/showthread.php?t=4661).

I basically just used his Idle Airflow Values. I believe if the Airflow Corrections or "Learn Limits" are too large (too aggressive), then that can contribute to higher (undesirable) idle swings.

If I follow the Idle Tutorial logic..too much airflow correction, especially for such small swings in Rpm's (normal for larger cams) will cause that widely varying idle swing..and contribute to surging and or stalling.

[DrkPhx]

What tables are you referring to? I've tried every table in the Learning tables and always come back to the stock (or near stock) values. I have a pretty healthy cam in my setup.

[DrkPhx]

I should add those table are very sensitive to adjustments. As Weatherman mentioned adjusting too much can cause even worse idle swing.

[efizjb]

Thanks weatherman...you M6 guys have it much easier than us A4 guys!!!! I've got it all fairly good except for sometimes when shifting from park to drive or reverse...I've overcomponesated the desired table for in gear...I got to look closer, I might be missing something in timing or A/F.

I was thinking maybe opening up the learn limits in drive might help a little bit, but as you said it might cause swings...

[5.7ute]

What is your actual issue when going from P/N to in gear?
Like Drkphx has done, I have gone back to near stock values as changing these tables can bring in other issues.

[Aloicious]

Are there any negatives to increasing the values both positive and negative? I've done a lot of research here and used the idle tuning tutitorials. In my searches I've found only a "couple" mentions relative to changing the learn limits.

I'm assuming it can only help widening these limits on a heads/cam car. However are their any negatives to doing this, or making them too big which would have a negative impact on the idle overall? As there's so little mention of it should they not be touched?

I believe you're referring to B4324, B4325, B4328 and B4329? the idle learn drive high and low limits. from my research I've found these are simply the limit to how much the STIT's and LTIT's can correct. I have raised all the high limits to 8 g/s, and lowered all the low limits to -8 g/s while trying to combat my coasting out of gear idle surge. it really didn't make a difference for me because if you have your desired airflow table correct, you shouldn't need to make large idle trims. I kept these tables at 8 and -8 and have seen no negative consiquences. I think the biggest area that they would come in handy changing is if your desired airflow table is largely incorrect and your STIT and/or LTIT's are actually reaching the limits, this would mean you would have to do more RAFIG logs, and spend more time working to get a correct B4307. if this is the case, you could raise (and lower) the limits, to allow the STIT's and LTIT's actually trim to what is needed rather than just hitting the limit and stopping. which would mean you could do less RAFIG's and spend less time correcting B4307 because your trimming data would be more accurate off the bat.

if that makes any sense. I've been up for a while and I don't think the eloquence portion of my brain is enabled anymore tonight.

[efizjb]

What is your actual issue when going from P/N to in gear?
Like Drkphx has done, I have gone back to near stock values as changing these tables can bring in other issues.


Thanks for all the responses guys.

5.7, I get an intermittant stall when going from park to drive or reverse. Seems fine when fully warmed up, mostly when cold. I've bumped up the desired airflow in gear probably more than necessary with no change. For some odd reason, it mostly only happens going to reverse, if I go straight from park to drive it usually doesn't happen. This makes no sense to me, I would think load going to reverse or drive would be the same. I don't know if there are any specific PIDs I should log to catch it. AFR seems fine, but I'm leaning towards possible blip in timing swing. My idle timing vs in gear is 6 degrees apart, so I wouldn't think thats the culprit. Warm IAC counts are right around 60.