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Old 05-21-2006, 04:27 PM   #1
Tea cups
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Member#: 103136
Join Date: Dec 2005
Default knock correction explained?

I thought I knew what the "knock correction" parameter meant when logging, but after reading an explanation on the Ecutek site, I think I'm not so sure. I thought Knock correction = (ignition correction table value * IAM/16) +/- (fine knock learning). With fine knock learning being the fluid positive or negative values stored in RAM for different load/rpm sites to be added/removed from the permanent ignition correction table in ROM.

From the Ecutek site, it sounds like Knock Correction = Fine knock learning. So, the knock correction value you log has no direct reference to with the igntion corrections table, it is merely a +/- value based on recent knock activity post-reset. So, logged ignition timing = (base ignition map)+(ignition correction map * IAM/16) +/- (fine knock learning).

Is this right, or am I confused?

Here's the quote from Ecutek:

"Ignition Timing
Overall ignition timing that the engine is currently running, incorporating the knock correction component described below.

Knock Correction
The number of degrees added or subtracted from the ignition timing based on the amount of knock detected. Positive values are ignition advance (due to the absence of knock). Negative values are ignition retard (due to the presence of knock). These ECUs run active knock correction, and it is quite normal to see -3 to + 12 degrees of correction."
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Old 05-21-2006, 05:34 PM   #2
FRSTi
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Member#: 34180
Join Date: Mar 2003
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Vehicle:
2011 EDM STi sedan
1998 JDM 22B STi

Default

Quote:
Originally Posted by Tea cups
I thought I knew what the "knock correction" parameter meant when logging, but after reading an explanation on the Ecutek site, I think I'm not so sure. I thought Knock correction = (ignition correction table value * IAM/16) +/- (fine knock learning). With fine knock learning being the fluid positive or negative values stored in RAM for different load/rpm sites to be added/removed from the permanent ignition correction table in ROM.

From the Ecutek site, it sounds like Knock Correction = Fine knock learning. So, the knock correction value you log has no direct reference to with the igntion corrections table, it is merely a +/- value based on recent knock activity post-reset. So, logged ignition timing = (base ignition map)+(ignition correction map * IAM/16) +/- (fine knock learning).

Is this right, or am I confused?

Here's the quote from Ecutek:

"Ignition Timing
Overall ignition timing that the engine is currently running, incorporating the knock correction component described below.

Knock Correction
The number of degrees added or subtracted from the ignition timing based on the amount of knock detected. Positive values are ignition advance (due to the absence of knock). Negative values are ignition retard (due to the presence of knock). These ECUs run active knock correction, and it is quite normal to see -3 to + 12 degrees of correction."
Your understanding is right for me.

The Ecutek site is correct also, but quite confusing...

I would have explained this way :

Ignition Timing
Overall Ignition Timing is the total timing the engine is currently running, incorporating the base map ignition timing plus knock correction value described below.

Knock Correction
The number of degrees added or subtracted from the ignition timing based on the amount of knock detected.
Positive values are ignition advance values on top of the base map ignition timing (due to the absence of knock).
Negative values are ignition retard applied to the Overall ignition timing (due to the presence of knock).


NB the difference between overall ignition (total ignition) and ignition timing (base map).
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Old 05-21-2006, 06:13 PM   #3
Tea cups
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Member#: 103136
Join Date: Dec 2005
Default

Quote:
Originally Posted by FRSTi
Your understanding is right for me.

The Ecutek site is correct also, but quite confusing...

I would have explained this way :

Ignition Timing
Overall Ignition Timing is the total timing the engine is currently running, incorporating the base map ignition timing plus knock correction value described below.

Knock Correction
The number of degrees added or subtracted from the ignition timing based on the amount of knock detected.
Positive values are ignition advance values on top of the base map ignition timing (due to the absence of knock).
Negative values are ignition retard applied to the Overall ignition timing (due to the presence of knock).


NB the difference between overall ignition (total ignition) and ignition timing (base map).
I'm still trying to figure out how the ignition correction table comes into play. I know it is the maximum amount of correction advance that can be added to base timing and this max drops when IAM is below 16 (ignition correction x IAM/16).

So, the knock correction logged can never be greater than the (ignition correction x IAM/16) value referenced by load/rpm? So, the IAM only impacts the maximum knock correction allowed, not the immediate (fine) knock learning that is stored in RAM?
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Old 05-26-2006, 04:49 PM   #4
FRSTi
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Member#: 34180
Join Date: Mar 2003
Chapter/Region: International
Location: Ahead of the pack
Vehicle:
2011 EDM STi sedan
1998 JDM 22B STi

Default

Quote:
Originally Posted by Tea cups
I'm still trying to figure out how the ignition correction table comes into play. I know it is the maximum amount of correction advance that can be added to base timing and this max drops when IAM is below 16 (ignition correction x IAM/16).

So, the knock correction logged can never be greater than the (ignition correction x IAM/16) value referenced by load/rpm? So, the IAM only impacts the maximum knock correction allowed, not the immediate (fine) knock learning that is stored in RAM?
With a 16 value, you will not go over the maximum applicable ignition correction value.
The 8x8 fine learning table will only be used to store negative values and then remove some timing, not to add any further degree...
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