Positive Back Pressure EGR Valve
A control valve, located in the EGR valve, acts as a vacuum regulator valve. The control valve controls the amount of vacuum to the EGR diaphragm chamber by bleeding vacuum to the atmosphere during certain operating conditions.
When the control valve receives a back-pressure signal, through the hollow shaft of the EGR valve, pressure on the bottom of the control valve closes the control valve. When the control valve closes, the maximum vacuum signal is applied directly to the EGR valve allowing exhaust gas recirculation.