How to test the EGR valve?

[90mustangfan]

after getting codes 41,91, I replace the oxygen sensors and that fixed those codes, Well I reset the computer and drove the car and the CEL light came then shut off. So I got home and DID a KOEO now I get code 31 in CM and KEOR: 11(pass)...I was reading On fordfuelinjection.com... And I could need a EVP sensor or a new wrg valve or the vaccum to the sensor isnt working(the vaccum Im sure is good) So how do I test the egr valve? Do I put vaccum on it and see if it holds or leaks? And for the EVP sensor how Do I test that? Do I put vaccum on the EGR and measure the voltage on the EVP?

 

[Mustang5L5]

Take EGR off, clean the hell out of the plunger.

Then, push the plunger in, hold your finger over the vac port and let go of the plunger. It should hold open until you release your finger from the vac port

 

[90mustangfan]

OK I just tested it, I put 8 hg of vaccum and it didnt lose any vac. and the egr valve open and closed smoothly. So I guess the actual EVP sensor is bad...well there only 25 bux at autozone...

 

[jrichker]

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections.