RomRaider

I've had a long day, so maybe i'm missing something... but how could this occur, based on your explanation above?



I was driving in closed loop, constant throttle (~18%), AFR was steady (at ~13.5).

IAM* (raw ecu value) Fine Learning Knock Correction* (degrees)
1 -2.11
1 -2.11
1 -3.16
1 -3.16
1 -3.16
1 -4.22
1 -4.22
1 -4.22
1 -4.22
1 -4.22
1 -4.22
1 -4.22
1 -4.22
8 0
8 0
8 0
8 0
8 0
8 0
8 0



This was very soon after an ecu reset (reflash) and my IAM dropped from 8 to 1 when it hit some negative FEEDBACK KC values (-6) eariler in the log. Then, while still getting what i'm assuming is knock, the IAM jumped back up to 8.

Am I missing something?

Edit: My big concern isn't that my IAM is raising. This same thing happens in reverse, when there doesn't appear to be any -KC the IAM will drop off the map as well. I'm just trying to understand what i'm missing...

You cannot hope to monitor every change by logging. Things at the ecu level occur much too rapidly. Especially when you log too many parameters (which I suspect is the case here), although even with a minimal number of parameters you will still miss stuff. For example, IAM does not instantly change from 1 to 8. It would be more something like this: 1 to 5, 5 to 9, 9 to 7, 7 to 8. So, in the short time between one line where IAM was 1 and the next where IAM was 8, a lot had happened. And there is even a delay when the ecu is raising IAM! Of course, "delay" is relative. So, likely, with IAM at 1 and a requirement of a positive fine correction value with IAM so low, you entered a different rpm/load cell where the fine correction was a large positive number (or even the current value was adjusted to a large positive number in a short period of time -> given the low resolution of your log this wouldn't be impossible).

Remember, that except for when IAM <= 1, only an extreme fine correction learning value is required (pos or neg) to enter rough correction mode (among the other conditions). But that value itself does not determine which direction IAM will go (if all the conditions are met to enable a change). Only knock at the moment IAM is being re-evaluated determines that. Fine correction is learned correction not necessarily based on current knock. Also, just because feedback correction is negative doesn't mean the knock signal is set the entire period that it is negative. The ecu holds the correction for a time period even if the correction took care of the knock issue and advances the value back to zero in steps. So, you could have some negative feedback correction in your log and them IAM goes up. This would appear to be strange, but would be entirely possible.

Ok that makes more sense. Yeah I did have quite a few things i was logging... My resolution must have been way to slow to catch what was going on.

-KC and increasing IAM is what really confused me... Thanks for clarifiying this.

I need help understanding under what conditions IAM will be incremented?

What I have observed is upon reset, the IAM is at 0.5. After running at 0.5 bar boost for 5-10secs it will go to 1.0. The car will happily run at 1.0 for 1-2 weeks, and then slowly go down from 1.0 to 0.94 for a week or so, then 0.88 for another few weeks, then 0.81 and stabilizes there. It never seems to increment back toward 1.0.

Upon reviewing logs, I have also noticed that around the time when IAM is changed (say from 1.0 to 0.91), there is no negative KC, no feedback correction, no knock signal. There must be some logic for the ECU to change the IAM besides a severe knock. I wonder what could the logic be?

You need to re-read the OP. And keep in mind there's not enough resolution in logging to accurately monitor the knock signal. You would want to take a look at fine learning knock correction as extreme values are one of the conditions (not negative feedback correction or negative KC). However, realize that things can occur very rapidly at the ecu level that you might not catch when logging. In addition, there are many conditions that must be satisfied in order for IAM to be re-evaluated and are outlined in the OP.

Bill,

Are these threshholds the same for 32 bit ECUs (they seem to be close)? I am quite interested in this.

Thanks,

Gabe

It isn't as straightforward, especially in the later models, but generally it would be the following (ex. 06 wrx which is the typical rom I work with):

To exit from fine correction mode to rough correction (IAM) mode, the following requirements must be met:
1. Engine speed and load must be within the ranges specified by the 'Rough Correction Range' tables.
2. Timing advance (max) map value is greater than 4.0 degrees.
3. The last fine correction value (|x|) is greater than 3.8 degrees (that is, the absolute correction -> ex. -3.8 = 3.8)
4. No current feedback correction.

There's more to it that I haven't had a chance to mess with, but this is the general idea.

Bill,

Is there any requirement such as this one to enter rough correction as well and if so what is the multiplier:



Thanks,

Gabe

no, in general, what I listed was it, although there are situations where the mode can be changed/inhibited indepedent of the normal logic. I need to go through it again after I'm done with the defs and then update the original thread with a separate 32-bit ecu description.

Looking forward to the 32bit details.

Very helpful info.

FLKC is applied regardless of gear I assume. If I get a knock event in 5th gear, FLKC is negatively incremented for that specific load/rpm. If a minute later I go through the same load/rpm in another gear (2nd gear for example), that negative FLKC (learned from an event in 5th) is applied in 2nd, right?

yep

^^ That sucks..

Is there a possibility of putting that description into a flowchart of some sorts? I think it might be easier to visualise...

I don't know. I think that would be a pretty big flowchart.