Camshaft Position (CMP) Actuator System
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 (LY6, L76) and the 6.2 liter (L92) engine, the Park position for the CMP actuator and camshaft is 8.5 degrees before top dead center (BTDC) or 17 crankshaft degrees BTDC. The engine control module (ECM) can only command the CMP actuator to retard the valve timing from the Park position or advance the valve timing back to the Park position. The total range of valve timing authority is 31 degrees camshaft rotation, or 62 degrees of crankshaft rotation. The control range is from the Park position of 8.5 degrees camshaft or 17 degrees crankshaft BTDC, to 22.5 degrees camshaft or 45 degrees crankshaft after top dead center (ATDC).