Camshaft Position (CMP) Actuator System

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The camshaft position (CMP) actuator system is used for a variety of engine performance enhancements. These enhancements include lower emission output through exhaust gas recirculation (EGR) control, a wider engine torque range, improved gas mileage, and improved engine idle stability. The CMP actuator system accomplishes this by controlling the amount of intake and exhaust valve overlap. For the 6.0 liter (LFA) engine, the park position for the CMP actuator and camshaft is 14.5 degrees after top dead center (ATDC), or 29 crankshaft degrees ATDC. The engine control module (ECM) can only command the CMP actuator to advance the valve timing from the park position, or retard the valve timing back to the park position. The total range of valve timing authority is 23 degrees camshaft rotation, or 46 degrees of crankshaft rotation. The control range is from the park position of 14.5 degrees camshaft, or 29 degrees crankshaft ATDC, to 8.5 degrees camshaft or 17 degrees crankshaft before top dead center (BTDC).