VR Sensor Interface
MAPECU Variable Reluctance Sensor Interface
The MAPECU Variable Reluctance Sensor Interface is designed to convert the analog signal from a variable reluctance sensor to digital to enable the MAPECU3 or MAP-CU2 to display OEM ECU base timing. MAPCAL2 V3.1.x or MAPCAL3 is required to support Base Timing display. In the Toyota example below, the interface is connected to output of the G2 camshaft position sensor that corresponds to 10° Before Top Dead Centre (BTDC).
The variable reluctance sensor interface is not required for the MAPECU2 or MAPECU3 to control ignition timing. It is only required to condition an analog cam position sensor signal to digital. These analog sensors are generally called variable reluctance sensors. A variable reluctance sensor is a coil wrapped around a permanent magnet placed near a moving metal wheel. When the metal wheel passes near the magnet/coil sensor, small voltage fluctuations are generated in the coil. See the waveforms in the picture above.
The variable reluctance sensor interface amplifies and conditions these voltage fluctuations into a digital 5V signal suitable for the MAPECU2 or MAPECU3 KVF (digital) input. The MAPECU2 or MAPECU3 calculates the time difference between the top dead centre (TDC) signal and the previous ignition pulse to calculate the number of degrees before top dead center (TDC) ignition occurred. A valid TDC sensor signal from a cam position sensor must be available for the base time function to operate correctly. In the example above, the G1 or G2 signal is ideal. The NE signal is not suitable.
The base timing display and logging function utilizes the KVF digital input. The function is not available in KVF Intercept modes or when the KVF input is being used for Speed Cut Defeat or Speed Cut Adjust.
The variable reluctance sensor interface can be used to convert an analog sensor signal to digital for any vehicle application, e.g. dashboard conversions.