Computer Command Control - Port Fuel Injection

EGR Control Solenoid:

The Exhaust Gas Recirculation (EGR) vacuum control has a vacuum control solenoid that uses "Pulse Width Modulation" (PWM). This means that the ECM turns the solenoid "OFF" and "ON" many times a second and varies the amount of "ON" time (pulse width) to vary the amount ported manifold vacuum to the EGR valve.