Greetings,
I wanted to run my troubleshooting steps past some of the more experienced. I have a 97 F150 4.6L throwing a P0401 (EGR insufficient flow). I think I have a bad EGR Vacuum Regulator solenoid.
I've disconnected the green vacuum line from the EGR Vacuum Regulator solenoid to the EGR valve and applied a slight vacuum to the EGR valve. The engine RPMs down almost stalling. I'm guessing the EGR value is okay. Reconnected.
Moving to the EGR Vacuum Regulator solenoid. After engine warmup, I checked the voltage on the EGR Vacuum Regulator solenoid connector. It showed 12-13vdc. I assume that means the EGR Vacuum Regulator solenoid should be open.
Reconnected the plug to the EGR Vacuum Regulator solenoid and pulled the green vacuum line off the EGR valve, put my finger over the end and could feel a very slight pulsation.. no vacuum however. I lightly tapped the EGR Vacuum regulator solenoid with no change. Reconnected.
Disconnected the white / green vacuum line combo at the bottom of the EGR Vacuum Regulator solenoid. The white line had a solid vacuum on it. Reconnected.
If I understand the diagrams correctly, the EGR Vacuum Regulator solenoid should be open with 12vdc applied to the connector. This in turn should apply a vacuum to the green vacuum like going to the EGR valve.. resulting in the EGR valve opening.
Do I have a bad EGR Vacuum Regulator solenoid or should I move on to the Differential Pressure Feedback EGR sensor?
Thanks in advance.
Jason