AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 305)

EFI Components 299
© 2014 AEM Performance Electronics
CMP/CKP (Cam/Crank Position)
Cam and crank position sensors are typically either VR (Variable Reluctance) "Mag" or Hall
Effect. Hall Effect sensors use three wires and produce a digital square wave. VR sensors use
two wires and produce an analog sinusoidal wave. VR sensors are better for high temperature
applications and are less expensive than "Hall" sensors.
When the “teeth” on a toothed wheel pass by a sensor, the sensor creates a voltage pattern that
is used by the ECU for many important calculations. The example below shows two different
toothed wheels, one that rotates with the crankshaft. The other rotates with the camshaft (1/2
engine speed). Representative voltage signal patterns for one complete engine cycle (2
revolutions) are also shown. The calibration file must contain the proper settings to define this
pattern for the ECU.
The diagram above illustrates a very basic even tooth pattern along with fuel output phasing and
spark output phasing setups. Many different crank and cam input configurations are possible with
an AEM Infinity, however, the firmware used is specific to the timing pattern.