1990 f-150 302 with 106,000 and i failed emmisions for high nox but just by a hair,I looked at the egr and if i rev the engin and look in the egr where the little holes are on the side of it i can see the pintle raise up off it seat and when i let of the gass i can see it come back down,I`m guessing it is working right?I guess maybe i need to chang the o2 densor that is orignal one that came with the truck or retard the timing alittle?maybe i could use some 93 octane and alittle denatured achoal in it to pass?anyone have any ideas.

 

Well I can't really help you out with what exactly the problem is, but here's the procedure for testing the EGR valve to make sure it's functioning properly.

You'll need a hand vacuum pump depending on the outcome.

1) Install a suitable tachometer [I think this is so you can read RPM's while under the hood- if you have someone to read the tach for you, you should be fine.]

2)Disconnect the wiring to the IAC solenoid.

3)Remove and plug the vacuum supply hose from the EGR valve nipple.

4)Start the engine and let it idle with the transmission in NEUTRAL.

5)Observe the idle speed. If the engine idles, the EGR valve is functioning normally.

6)If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate, or by creating an intake vacuum leak. Do not exceed a typical idle RPM.

7)Slowly apply 5-10 in. Hg of vacuum to the EGR valve nipple using a hand vacuum pump. If the idle speed drops more than 100 RPM, inspect the EGR valve for blockage. Clean, inspect again for vacuum leakage, or replace as necessary.

That's straight out of my service manual step for step.

 

found the problem it was the vacuum soup can on the fender it had a bunch of holes in it underneath where it bolts the the wheel well.Got some firberglass and cloth and fixed her up nice.It wasn`t pulling enought vacuum to open the egr enough and now it`s opening all the way at 5hg.