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

MERLINS RALLIART & EVOLUTION-X TUNING GUIDE6.02-KNOCK TUNING – KNOCKBASEKNOCKBASE is the term used to describe the dynamic average noise threshold.When an incoming signal spike from the knock sensor/filter/amplifier systemexceeds this level, it is regarded as knock.The KNOCKBASE level is derived from the knock sensor signal level, after filtering,and then being passed through a dual gain amplifier. The knock sensor amplifiersystem can switch from gain=x3 to gain=x1. This is used to give the system a highdynamic range and possibly to prevent input signal overload. The amplifier operatesat high gain on low level signals. The resulting level as read by the internal analogto digital converter is then multiplied by the KNOCK MULTIPLIER value and thesingle/triple gain adders applied.The multiplier is used to multiply the difference between the present filtered knockADC and the long term average knock ADC, and the result is divided by the longterm average knock ADC. This is a dynamic noise reference level in effect, whichhas the ability to learn the engines noise v rpm characteristics.To update KNOCKBASE, the ECU takes the old value and multiplies it by 7, adds thelatest knock free noise level, then divides by 8. So it takes 8 ignition events to fullyupdate the KNOCKBASE.The figure below shows a logged power pull from 3000rpm to 7000rpm. The yellowline is the ECU generated KNOCKBASE, that the multipliers adjust. The pink line isthe knock sensor signal after the filter and switched-gain amplifier. The gaintransition point can be seen at about 4800rpm. Where the pink knock sensor signal"pokes" through the yellow curve you get a knock count, which is added to thecurrent KNOCKSUM value.REV: 0.K merlin@three.com.au Page 55 of 134