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datalogging knock : should i give more weight to "knock level detected" or the per cyl "knock table level" values?


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so i was poking around in my datalogs and discovered the "knock level global" and "knock level detected" values

the link ecu does windowing and filtering and we have the very nice per cyl "knock table level" values to refer to

the manual says the knock level global is a general value of all knock levels combined

and knock level detected knock level global minus knock threshold value

in my datalog i get knock table levels far below the set threshold level but i can get a knock level global reading above the threshold level and a knock level detected value thats positive.

i dont have my audio knock gear handy at the moment (yay messy storage units) - so going only off datalogs, how much weight should i give the global and detected levels if the table levels are well below the threshold value?


context : had it tuned on the dyno perfectly with no knock by the workshop - super happy with the results - then I went and upgraded the turbo since the tune and have removed some timing so i didnt get spikes above the threshold but after viewing the "newly discovered (for me) global and detected levels" and not having my knock gear handy im wondering if i should continue to trust the table levels or nuke more timing based on the detected level?

the left hand red highlighted bit seems to be sus

but the right hand one has a spike when the table values are down relatively speaking....

neither went above the tuned threshold

its going down to the dyno again next weekend and these spikes only appeared after i started to wash out the 100 octane to get back onto to 98 octane for the upcoming tune.

i get it tuned on 98 (with this time also getting a flex fuel tune with a blend of e100) and normally run it on 100 octane to have a "safety buffer" over the 98 it was tuned on - and that does quieten down the detected table level readings - but then i "discovered" the global and detected datalogged channels

aircon was not switching off or on at the time - and the downpipe from the turbo is *very* close to the firewall after the turbo change (i guess it really could have used a few more smacks with the clearance tool) - so should i watch the table levels - or the knock detected stuff until it gets back on the dyno next week?



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Knock level global and knock level detected are not very useful runtimes when using the (older) ign/fuel trim strategy as the knock level global is basically the raw signal from the sensor with no windowing applied as far as I remember.  I cant remember if it has the frequency filter applied or not either.  

Knock level detected was originally added for the normalised mode which uses knock level normalised so is more useful with that strategy. 

"Knock count global" will increment if any individual knock level exceeds the threshold so that is a good one to monitor for a quick overview where/if knock has occurred.  


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