Anyone know how to test one? I replaced EVR on my 95 460, F250 with the one from my capri since original truck EVR was leaking and allowing EGR at idle (very rough idle). Idle is now great, but after replacing EVR, I now get code 334 (EGR not providing enough flow or EVP not registering any change) and check engine light. EVP checks out at high and low resistance, no dead spots, Vref is 5 volts, and it is below the required .67 seated voltage (.33).

I T'd in a vac guage to EGR and wires to both sides of EVR. I get no vac to EGR at any time. I measured AC and DC volts, duty cycle, and frequency on EVR while driving around. I beleive the EVR works off duty cycle and measuring that sort of made sense. It starts out about 3% and goes up to 60% at moderate accel. I know EVR has constant 5V and ECM varies ground. Not sure if I am testing EVR correctly?

 

One for the archives. Turns out I had the vac lines reversed on EVR. Original plastic lines broke during engine replacement. None of the documentation I could find showed me which line went where, so I guessed. Anway, the vac line farthest away from electrical connector (the lower line if valve is mounted straight up and down and vent is on top) goes to intake man vac. The upper line goes to EGR. Anyway, I now have zero vac going to EGR at idle, full throttle and anywhere from 1-5 in Hg vac at varying points of part throttle (as it should be). Duty cycle on EVR ranges from idle where it is anything from .5-12% (bounces all over) up to about 57% under lighter loads. No codes/check engine light. Still have a tip in knock, am going to yank valve and clean it/pasages. Also, one correction from my orignal post. EVR has constant 12V and varies ground, not 5V as I first stated.