Syvecs Forums

Hi, I would like some help regarding tuning the Knock Control on the S8.

I usually find the Band Pass filter frequency using Goldwave and recording the sound on the dyno without and with controlled detonation so to find the best frequency range.

But what is confusing for me is how to tune the two Knock Base maps as its not related to engine speed as I usaully do it with other ecus.

I watched the YouTube video and I know that you need to open monitors in scal and adjust gain so each cylinder reads approx the same and then make some pulls on the dyno and data log it but im not sure if the 0 - 100 is related to engine speed.

Please can you clarify abit more on this particular important subject.

Thanks alot.

There are a few things to consider, the main one is the knock threshold tables and if you're used to a MoTeC or AEM then it might seem a bit strange.

Ultimately what you are after is a nice smooth knock trace for each cylinder, and then when you get a real crack of detonation a nice clear spike in that otherwise smooth trace. It doesn't matter if the knock values go up, or down with RPM (typically they go up) as the ECU will track the overall level to give you what is internally called "knockbase".

Sudden spikes will be much higher than the Knockbase value, and where the threshold table fits in to all this, is to create a new level "KnockThreshold", based on the KnockBase. So then we can for each cylinder a value that will generally follow the predominant knock levels, but somewhat higher, and when the clear spikes of knock pass this threshold, that's when the ECU determines that real knock has occurred. On the S8 we can use 2 tables, one for normal knock and one for severe, along with a further single threshold for preignition. When the knock level passes one of these thresholds we can retard a specified amount.

That's the basics, and it means that as the knock level changes with time or temperature, the knock control still detects knock effectively.

The other variables can be more subtle, like time constant, as they are programming variables sent to the knock DSP IC at startup to configure it, and they will change how the knock sensor output is processed into something that the ECU can deal with and make decisions on.

Thanks alot Pavlo, yes I am more used to AEM and Motec but now it is making more sense on how Syvecs detects knock, and abviously it takes time and practice to perfect the threshold tables to a particular engine on dyno and for every cylinder, but worth the effort