Merlins Ralliart and EvoX TUNING GUIDE Version K.pdf - EvoScan

MERLINS RALLIART & EVOLUTION-X TUNING GUIDE6.04-KNOCK TUNING – FALSE KNOCKThe knock events that you have logged have presumably now been assessed asFALSE KNOCK, but just to re-cap the basic principal:Real detonation will respond to reducing the ignition timing and/or increasing thefuels octane rating.False Knock will not respond to reducing the spark advance.The KNOCK MULTIPLIER v RPM table provides a way to alter the KNOCKBASEprofile, thus telling the ECU there is more engine noise at this load/rpm point,without loosing knock control. Adjust the value up at the rpm point where the falseknock is occurring.Here is the description jcsbanks provided to the Evo community on how this worksin the EVO ECU.“I would think of this as a KNOCKBASE predictor - ie the adaptive system isretrospective since it can only influence the KNOCKBASE upwards after the heavilyfiltered and slightly delayed (the digital filtering used adds a delay) noise level hasincreased. However, the right programming of the multiplier (and/or adder) by RPMwill give a combination of adaptive and predictive.The multipliers increase the KNOCKBASE, so if you increase the multiplier for agiven RPM by x%, then you increase KNOCKBASE by x% also. To recap,KNOCKBASE is the level that the knock sensor noise has to exceed after each sparkplug fires to cause that combustion event to register as knock and increase theKNOCKSUM. It will do this for every combustion event, so a small breach canquickly build to a big KNOCKSUM, so a small but persistent breach of KNOCKBASEwill give big problems. If you think about how it is designed, it makes sense that ifthis was real knock and not going away quickly with KNOCKSUMs applied to theignition timing that it would be appropriate to get aggressive with it quickly toprevent engine damage. By use of the OCTANE NUMBER, the ECU will always aimto have KNOCKSUMs of 5 or less in the long term.”Somewhat encouraging to note that at the time of writing, nobody has reportedhaving to raise the multiplier by more than 20% to clear false knock!REV: 0.K merlin@three.com.au Page 62 of 134