[ExScoobyT]

I am not suggesting that there are not harmonics present in the crank / cam rotational positions, however that is easily dealt with in the software, which no one on here is able to inspect. The fact that the CAS has 360deg markings and 6 windows suggest to me that the RPM signal is processed in varying ways according to the RPM (Correlation of cylinder windows with crank angle degree, coupled with rotational acceleration rationality checks - note the varying window lengths). The whole nissan CAS issue was only raised after multiple users (me included) had issues with the piece-of-crap AEM ecu that is clearly unable to process the signal correctly (even at idle)

Do you really think Nissan would use a sensor to determine timing that is both more expensive, more complex and less effective than a crank wheel? The car was manufactured for what 9 -10years? I must have missed the change to crank AS on grp A racers, R34 or Z-tune, or mines or HKS or or or or......

For info the 360deg markings would give rise to a 24Mhz signal at 8000rpm, a 60-2 gives a 8Mhz at 8000rpm. I also see RPM saw-toothing when logging from datalogit, however this is not necessarily the same signal used by the ECU to process spark timing (you don`t see the timing jumping around with RPM for example). There is a world of difference between the signals passed on the I/O bus and the sample frequency used and the internally processed signals.