Knock Correction Maping
 

What is the goal of changing the Values in the "knock Correction Map"? Some seem to modify the ignition curve by changing values to the Correction Map while others change the "Ignition Base Map". Both ways can end up with the same final ignition value but what are the benefits and negatives of either. How does limiting or expanding the degrees of timing that the ECU can change help or hurt?

@jamesm

Oh Wait....

Either is a valid method and will achieve the same results.


If, however, you do encounter enough knock to drop the IAM the percentage is taken from the advance table. So if the total ignition timing is identical, when the IAM drops the timing taken out will be larger if the advance figure is larger.


I tend to like a flat advance table so that it's easy to keep track of changes.

Are you saying flat meaning giving the knock correction map all the same values in every cell?
I made a quick excel sheet to add both the table together so i can see the difference in the end ignition value.
I am a little confused on the IAM. When does the IAM drop to a lower value. I read when 50% of the cells have changes it drops .1? I would think the ignition map would have to be very poor in order to have 50% of the cells change?

Did a thread on knock correction see below.

Just remember the Knock Correction Max A table is the amount of knock correction the ECU has at its disposal to correct knock, so if you take from their you limit the correction the ecu can apply as that is you KCA or KC LEARNED value, best to remove the timing from the Base Timing B table.

Also i believe if the value of the knock correction table is below about 3 then it disables coarse knock correction

Stupid mod

On mine I ramp it up as the load increases but it's a flat value in each load column. But that is just personal preference.


IAM drops when it detects "severe" knock, which just means a continuous set of knock events. It has nothing to do with cell count as far as I know. The amount it drops isn't usually a single point value either, it will vary.

So the only down side that I can think of would be that if the Knock Correction table values are larger than the standard table and the IAM drops it will pull a higher percentage out of the final ignition value out reducing performance more quickly. The opposite would be true if there is not enough Knock Correction value than the IAM might not have enough or be to slow to pull timing out if severe knocking happens.

AFAIK the values in the Knock correction table become you KCA or KC LEARNED value, this is the amount of correction the ecu has to play with to correct knock both fbkc and flkc and IAM. I also believe that if the value in the knock correction table is less than about 3 coarse correction ie fbkc is disabled and iam will not drop, but you still have knock.

Remember you logging the ecu attempt to correct knock, not the ectual knock itself.

FBKC is active no matter what is in the advance table, and I think the same is true with FLKC. However you are correct that the IAM will not drop unless the value is more than a given level.

yes i believe that is true however if the KCA value Knock correction A value has been reduced then i think that all the correction the ecu has available to adjust. It micgh detect say -3 of knock but if KCA value in table was onlt say 2 at that point it can only pull 2 degrees out of timing i think, just think its safer to leave the KCA alone and pull from base timing :)

Depends on what you're doing though I guess. I change the base table to adjust anything on low-mid load to remove knock. In the high load areas, I have a flat table of (for example) 6 degrees. Now if I prove I have no knock, I up that by a flat figure, say 0.7 degrees. If I get knock after that, I can reduce where necessary in the advance table but I can continue to add timing in other areas. It's clear as day the next time I do the same where I should not add any more timing and where I can. This would not be the case on the base table, unless you have a very good memory or note it down. In my eyes, adjusting the advance table is the easy solution. Once you get to the stage where you are happy, you can always adjust the base table and flatten the advance table again, or have it how you like.

yes that method would wotk fine, i just worry about guys pulling 2 or 3 degrees out of the knock advance table and leaving little in it for the ecu to work with