PSmalls::AnalRetentiveNumbNut

And let's say for a second that all the major tuners do actually have control. Why did a majority of them choose the exact same adjustment? Just seems odd to me.

JD's conspiracy theory #2,276

Mike2kS4

IAT is always a variable in timing. It doesn't really intervene, it just takes part in the calculation. Now, the results of that calculation follow the predictable curve of how IAT would affect optimal timing.

So, the ECU knows, in a look-up table used during calculation, that 30degF IAT's at high load are very safe, so the results of that calculation result in no adjustment of timing angle... the "IAT" variable is still there, but its value is approximately zero. Once you start hitting 125deg IAT's and high load the timing calculation will result in a value that's maybe 7-10 deg lower than our 30degF calculation.

Here's another key point, Due to this calculation also being load and RPM dependent, the curve will change too. In the midrange, where peak torque and cylinder pressures are, the calculation usually results in the timing curve bowing down more pronounced in this range.

Mike2kS4

This is actually a *very* good discussion

cjk

I agree toooooooooo! :P

Asking the right question has always been fun!

Thanks Mike!

nyet

which is also based on cylinder pressure (calculated from load, which comes from MAF) and RPMs?

then, its adjusted by the CF (long term). CF can move around (slowly) based on "medium term" knock events that the ECU thinks indicate stuff like octane. these effect ALL cylinders equally

short term knock events can bump a particular cylinder's current retard down. It can recover too, (only?) if short term events go away, but they do not affect CF like the "medium term" knock type does, and they do not affect all cylinders equally.

does this sound reasonable?

based on these terms, can we define what each of the logged timing numbers mean? in particular, is "retard" the combination of CF AND short term retard? i.e. if you subtract current timing from retard, you get the original uncorrected "optimal timing" that we started with (which IS dependant on IAT)

OR is "retard" simply short term retard, and does not represent the effect of CF?

is CF 1:1 with degrees, or is there another equation that translates CF into a retard amount (e.g. involving load or RPM?)

Finally, when people talk about the ECU's correction limitations, are we talking about short AND long term correction summed? or just short?

hopefully i can translate all of this information into a useful article.

once i get the basics hashed out, im hoping you can help me with fueling

Ochlockonee

positive way. My reply may have sounded a little too absolute to you but it's not really an opinion I've expressed. When it comes to electronic engine managment, I'm knowledgeable and experienced. I'm not looking for approval or to gain a following on this board, just to quietly contribute.

When you made this post, it reminded me of something Mike2kS4 said a while back about how the ME7 seems to find ways to pull more and more timing. The statement was not totally clear but seemed to imply that once CFs got really high, the ME7 can find a way to give more room for safety based solely on the high CFs. I know that to not be true for any brand (supplier be it Bosch or other)of processor that I've been factory trained to diagnose including the Kias, Mazdas and Nissans that Ford has sold. I see absolutely no reason why Audi or Bosch should reinvent the wheel in regards to knock control. I didn't post then because I don't like disagreeing with Mike or you for that matter but it seems to have been a mistake not to ask him to clarify what he meant since you, NigelS4 and B5Qship have referenced it here. I wanted to make a point here of disagreeing for posterity. After all this a point where we are really playing with fire here and I want no misunderstandings.

So to recap, once the ecu has pulled 15 (or 16 haha) the ecu HAS reached it's limit.

nyet

we need as much open discussion as possible, hopefully without stepping on each other toes.

i am trying to get as much of this information in a digestible format as i can, and your cooperation is vital!<ul><li><a href="http://s4wiki.com/wiki/Timing">your comments appreciated</a></li></ul>

Mike2kS4

But I've never seen it... Must be an MTM thing.

Ray, your experience, knowledge and well-spoken nature is much appreciated here. Please continue to share as much as possible.

PSmalls::AnalRetentiveNumbNut

Keep on contributing, Ray. One thing is clear, you know a hell of a lot more than me. One of the few reasons I'm here is to learn. If people like you stay quiet, that won't happen. I'm all for some nice discussion as long as everybody stays open minded and doesn't get defensive or argumentative.

"So to recap, once the ecu has pulled 15 (or 16 haha) the ecu HAS reached it's limit."

From what I'm reading, it seems like you're correct...in regards to long term. However, my understand prior to this sub-thread was that the ECU still had the ability to pull additional timing in the short-term as a safety precuation...and Mike's posts have further confirmed that.

Imolavirus@BuehnEngineering

"you can't handle the truth"