Theory Of Operation

The Dual Stage Engine Oil Pump uses vanes and a moving element that is controlled by a solenoid to produce oil pressure to the engine in two regulated pressure stages (Low/High). In low pressure mode, the oil pressure will increase naturally with engine speed. When switched to high pressure mode the oil pressure is increased and is fairly steady. The Oil Pump Solenoid, mounted on the pump, is used to vary the displacement of the oil pump. The Powertrain Control Module (PCM) controls the solenoid operation. When the solenoid is energized, a bypass oil circuit is opened. This changes the eccentricity of the mechanical pump to lower the oil pressure (low pressure mode). The Engine Oil Pump is operated in low pressure mode during most operating conditions to reduce engine load, increasing the efficiency of the engine. The pump is switched to high pressure mode when engine operating conditions require a higher oil pressure. This is achieved by de-energizing the solenoid.

The minimum engine oil pressure is approximately 82.7 kPa (12 psi) for any operating condition. Anything less than this pressure could result in damage to critical moving parts. The maximum engine oil pressure is limited to 1000 kPa (145 psi) by the pressure relief valve. The oil pressure in the main oil galley of the engine can be checked by monitoring the Engine Oil Pressure (EOP) Sensor on the scan tool or using a mechanical oil pressure gauge.