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No, not necessarily.

The way the Subaru ECU hands knock sum between FBKC, FLKC, and IAM is murky water.
 

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when the ap is showing fine knock learn but no feedback knock does that mean its unlearning that knock?
At a very high level, Subaru has three different forms of knock control:
1) Feedback Knock Correction. This is a reduction in ignition advance when the knock sensor detects detonation. This is always either a zero or negative value.
2) Fine Learned Knock Correction. This is generally a reduction in ignition advance that is preemptively applied at specific RPM / Load ranges in an effort to prevent detonation that has repeatedly occurred previously. Advance is slowly added back in and it sees whether or not the vehicle experiences detonation. If all is clear, another bit of advance is added. In stock form, the advance value is typically ¼ the retard value (.35° vs -1.4°), meaning that it takes four iterations of testing before your FLKC value is cleared. This is typically either a zero or negative value, but in the event that your vehicle has gone into rough correction mode, FLKC can be positive values, as it slowly tests the waters to see if the IAM/DAM can increase back to its full value.
3) Rough correction (IAM / DAM). This is a reduction in ignition advance that is applied to the entire ignition advance table. On 16-bit ECUs (e.g., 2.0L WRXs), the IAM/DAM is a value between 0-16; on 32-bit ECUs (e.g., 2.5L vehicles), the IAM/DAM is a value between 0-1. In stock form, 16-bit ECUs have sixteen different values it can be (e.g., 16, 15, 14, 13, etc.), while 32-bit ECUs have eight different values it can be (e.g., 1, .875, .75, .625, etc.). The reduction is (IAM or DAM) / Max. For example, if IAM/DAM is 12 on a 16-bit ECU, it would only apply 75% (12/16) of the advance specified in the table.



Ignition Total Timing = [Base Timing] + (IAM or DAM) / Max * ([Ignition Advance]) + FBKC + FLKC + Compensations (e.g., Coolant Temp, Intake Temp, etc.)
 

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Discussion Starter #4
well im assuming my car has a 32 bit ecu then because the dam only goes between 0-1.

i had my first dam drop event a few days ago that's why im bringing this up. it only dropped to .875 and got back to 1 fairly quickly, probably not even 30 miles of driving. i knew it would be inevitable but still feels bad, especially knowing it was my fault. this car makes boost so fast ive let it get a little too high in 4th and 40ish mph i guess 1 too many times that day. ive read countless people talk about this already and nearly everyone seems to come to the conclusion that it must have been bad gas. im not sure if they are just lieing to themselves or i am just not as careful as i thought, but im pretty sure my gas is fine.

i dont remember hearing audible knock but i dont think ive ever actually heard engine knock before, any suggestions on accurate youtube videos? or would any engine sound similar enough to each other to just google it?

also is iam used interchangeably with dam? or is dam the new name and iam the old?
 

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Stanley Yahtzee said:
also is iam used interchangeably with dam? or is dam the new name and iam the old?
They are interchangeable. OpenECU uses "Ignition Advance Multiplier", while Cobb AP uses "Dynamic Advance Multiplier".
 

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well were on knock control , what frequency are u guys zeroing in on in ej25 ? I can easy hear knock low when under 2k but never heard it up high. Mine's set on 10.9kHz , think oem is just over 11kHz. Last data grab i registered 0.72db only driving medium conditions at 2400rpm, and i doubt it knocked and didnt count it. I have not fine tuned it yet as im not going over 13psi till i know i got it set right. So keen to push some timing/boost but not till i learn this knock system 1st.


And the long term trim on mine basically takes a little one day then puts it back the next. elite 2500. Same as the deflection in the cam belt from one side to the other. little one day then put it back the next. Think I need to let the LTT go for a week and see what happens. Reckon it will be balanced out again.
 

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Discussion Starter #7
well were on knock control , what frequency are u guys zeroing in on in ej25 ? I can easy hear knock low when under 2k but never heard it up high. Mine's set on 10.9kHz , think oem is just over 11kHz. Last data grab i registered 0.72db only driving medium conditions at 2400rpm, and i doubt it knocked and didnt count it. I have not fine tuned it yet as im not going over 13psi till i know i got it set right. So keen to push some timing/boost but not till i learn this knock system 1st.


And the long term trim on mine basically takes a little one day then puts it back the next. elite 2500. Same as the deflection in the cam belt from one side to the other. little one day then put it back the next. Think I need to let the LTT go for a week and see what happens. Reckon it will be balanced out again.
it sounds like a high pitched ping right? totally different than an engine normally sounds? all ive ever heard my car do is groan when under load but never any pings. is it difficult to hear or is it pretty loud?
 

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You will likely never hear knock with your own ears

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Discussion Starter #9
so i guess i just have to take it on faith that my engine is healthy as long as dam drops arent too common then? i mean without going very deep into this that is...
 

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Stop worrying.

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Discussion Starter #11
its not so much concern as it is frustration. im a somewhat lazy person, and yet i strive for knowledge. i see this problem as something id like to understand fully, yet is so utterly complicated that the amount of time/dedication it would to take to understand it is certainly not worth the effort because weather i understand it or not my car is most likely fine. i just have to let it go, i know more than enough, i hope.
 

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Would anyone have an answer to perhaps ghost knock ? I get a feedback knock read when I go wide open throttle but there is no drop in DAM OR FINE KNOCK LEARN this is a new short block however with 1200 miles At the moment.
 

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How much timing is pulled from the FBKC?

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