Can anyone tell me if it's possible to bench test the ERG solenoid for a 1997 Ranger 4.0?

Thought mine was bad and bought a new one from Motorcraft. That one acts the same as mine did : (

There are two ports on this thing. The bottom one is for vacuum coming in and the top leads to the EGR value. Common sense would seem to say that when the solenoid is energized it will either:

1) allow vacuum from the bottom to exit out the top or

2) prevent it from doing so and close off the connection between them

However, I do not get this. Not on my old one or the new one. There does not appear to be an unhindered connection from the bottom to the top port.

Has anyone any experience on how this solenoid actually functions and how to test it?

 

Here is a picture of the EGR solenoid. Bottom port is vacuum in and the one above it is to the EGR valve. With no current applied, there is a connectin between this second port and the internal "atmospheric" port in the cap. I assume this third port is to let air back in to the EGR to allow it to reset.

Applying 12vdc to the terminals will block off the connection from the second port to the internal "atmospheric" port in the cap. One would think that a clear connection would then be made between the bottom vacuum port and the middle port to activate the EGR.

But I don't seem to get that happening... old part or new part. Thoughts?

 

Found an article on the web showing how to test this solenoid in the vehicle using a vacuum meter and driving the car. Will give that a try tonight.

 

That looks like an EVR solenoid which by design is vented to the atmosphere. I suspect that's why your bench test doesn't work.

Check out: Ford DPFE/EGR system

 

If I remember correctly (and I might not be), i sucked on the nipple and then applied 12v and it changed, its ghetto, but seemed to indicate a working unit. When I say changed, meaning it passed air, then didnt (or the opposite).

 

How is this not an unmetered vacuum leak?

I'm experiencing similar confusion to the OP on my '94 2.3 Ranger. Was expecting the system to be sealed when the PCM doesn't ground the solenoid, and pass through to the EGR valve when grounded. There must be something important I'm missing here - why is it vented to the atmosphere at all?

 

fastpakr, the explanatory article at Rockledge site explains that the EVP valve has a 'duty cycle', meaning it can be 'buzzed' on and off at different rates. The faster the buzz, the more or less vacuum is vented to the atmosphere. The opposite speed of the valve 'buzzing' would feed more vacuum to the EGR diaphragm, thus opening the valve more, and passing more gas through to the intake.
The DPFE 'knows' how much EGR gas is flowing because of the pressure differential across the metered disk embedded in the EGR tube. When more gas is being fed, the pressure difference would be larger, as the exhaust gas passing is being allowed to escape through the EGR valve, so no or less pressure is created. Opposite pressure difference, where no gas is passing, and thus zero pressure difference(the gas is just 'sitting' in the EGR tube) would mean no EGR is flowing. The DPFE senses the pressure and reports it to the ECM.
The EVP is a 'dithering' type valve, that is neither open nor closed, and always leaks a bit. The leakage can be more or less, and more or less gas will flow, pressure change, and thus we have 'control' and a 'reporting system' for the EGR flow.
Perhaps the amount flowing is so small (depending on aperature in the metering disk to create a pressure difference) that idle is not affected.
If you have concern about unmetered air leakage affecting idle, disconnect the two hoses, and plug them both. Operate the engine and observe if there is a difference in idle.
tom