Phased CAM Fault Simulator

PCAM, a Phased CAM Fault Simulator device, facilitates development, calibration, and validation of OBD monitoring of an engine’s camshaft timing with respect to its crankshaft. For example, see the excerpt at the bottom of this page from California’s OBD II requirements for Variable Valve Timing (VVT).

The ECM uses sensors to detect the position of the crankshaft and camshaft(s) as they rotate. From these sensor signals, the ECM controls ignition and fuel timing under various speeds and loads, as well as valve timing for engines equipped with VVT. If the phase relationship of the Crank and Cam signals falls outside acceptable limits, the ECM’s On-Board Diagnostic (OBD) is supposed to flag this error and illuminate the Check Engine Light if it persists.

Mechanical engine faults that might cause such a condition include timing chain issues (wear, mis-assembly) and problems with control of VVT (if so equipped) – likely resulting in increased tailpipe emissions. As an alternative to laboriously creating such mechanical engine faults in order to test the OBD, engineers and technicians can simulate such failures by using this device to electronically modify the signal from the CAM sensor before it reaches the ECM. The modification consists of delaying (or advancing) the CAM signal by a user-selectable amount of phase error expressed in crank degrees.

OBD II Title 13, California Code Regulations – VARIABLE VALVE TIMING AND/OR CONTROL (VVT) SYSTEM MONITORING.

(13.2.1) Target Error. The OBD II system shall detect a malfunction prior to any failure or deterioration in the capability of the VVT system to achieve the commanded valve timing and/or control within a crank angle and/or lift tolerance that would cause a vehicle’s emissions to exceed 1.5 times any of the applicable FTP standards.