I have a 93' f-150 with a 302, my check engine light comes on for about 30 seconds and then goes off. This happens about every 3-4 minutes. The code came back as EGR insufficient flow. I cleaned it out and took the EGR valve off and the plunger works fine on it. I also replaced the ERG sensor that sits on top of the valve. The light still comes on and the code is for insufficient flow. Should I just try to replace the valve or is there something else I can do? I took the positive battery cable off for about 2 minutes, I'm not sure if that's the right way to clear the code.

 

I think those engines had issues with the EVP (EGR Valve Position sensor), but I'd verify proper operateration of the EGR by putting vacuume to it. The engine will run like crap at idle with the EGR open. If these check OK, all that is left is the solinoids, hoses, wiring and computer.

 

That engine has no sensor for EGR flow, so you have to refer to the older definition of that code number. It's really telling you that the EVP isn't moving the way the EEC wants it to.

What moves the EVP? The EGR.

What moves the EGR? Vacuum coming through the EVR.

So start by checking those old, brittle plastic vacuum lines (especially the red & green ones) for cracks & leaks. Then check the coffee can on the R wheelwell for rust/cracks, and the white line going to the recirculate motor under the R hood hinge for sunlight degradation.



Then use a Haynes manual or Ford service disk to test the EVP.

No, that's not the right way to clear the codes. Read this thread. If it's too boring, you can find a similar article on RJMInjectionTech that's more reader-friendly.