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WRX V11 knock threshold in log higher than set up value


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Hi Adam,

Need your advice, after done with fuel tuning I set up knock threshold, I pulled ignition by 6 degree from base map to make sure no knocking, set up knock threshold table and run the car. The log result shows that in some cells threshold value in log higher than on table.

Attached is the file and log file

Thank you


pull ign 6 deg.pclx log pull 6deg.llgx

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This is how normalised mode works. 

With normalised mode the ecu is comparing the noise level of the current combustion event to the previous few "learnt" combustion events.  If you are operating under reasonably stable conditions then suddenly increase load or RPM, then the first few combustion events at that new higher load will now be generating more noise than the previous events it is comparing to.  So to account for this, when there is a sudden change in load or RPM (this is determined by the RPM/MAP/TPS delta level settings, then the threshold is increased by the "Threshold gain" for the number of cycles set in "Delta hold".   

With normalised mode you would usually have a "flat" threshold table, and the threshold should only need to step up for a short time when there is a significant change in load or RPM.  You should not need to increase threshold with RPM or boost like your threshold table is, this suggests something is not right in the setup or possibly mechanical.  I notice you have a 2.5L whereas our car was a 2.0 so possibly the knock frequency is not ideal.  You could try it at 6,7 and say 13Khz to see if the noise levels look less erratic.  Your ignition advance is quite low so I doubt there is knock, but it is a little odd that your cyl 4 knock level is mostly the one that is erratic.  

A quirk I found in our subaru was the sharp click from the AC clutch turning on/off in auto mode would cause a spike in knock level, I got around this by disabling knock for a few tenths of a second before the clutch switched on of off.  I see that has caused 1 spike in your log but it is not your main issue, just something to keep in mind if you start seeing random spikes or retard.  

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