1996 5.0 p0401 problem
 

I have a 1996 f150 and its setting code p0401-egr insufficient flow detected. If I rev the truck up slowly it will miss pretty badly but if I disconnect the egr vacuum hose it goes away. I have left the vacuum line disconnected and still get the same code after a couple days. Anyone have any idea of what it might be. I pulled the egr to see if any thing was stuck in it and it looked clean. Any help would be great.

Thanks

Make sure it's diaphragm holds air/ Vac. & check EGR regulator function. Check for other Vac related leaks. What's the warm curb idle like?
http://www.fordfuelinjection.com/?p=43

Then there's the position sensor itself.
http://www.fordfuelinjection.com/?p=35

Curb idle is good with the vac line connected or disconnected. I will check out those other 2 items

There should be no Vac coming from the regulator to the EGR valve at warm idle. Should be full vac at, say 2000 rpm.

At the vacuum line that goes to top of EGR at idle has maybe .5inHg. It goes to 5inHg at part throttle at maybe 1200 to 1500 rpm for about a second and than goes back to .5inHg up to high rpm. I'm not positive on the rpm since I do not have a tach. I don't think it should be going back to 0 like that. At the bottom port of the EVR from vacuum source I have 21inHg vacuum.

5 in Hg would be right for a little over 1/2 throttle. You should have 0 vac from it at idle. Did you you read the link I posted regarding the regulator & testing? Remove the connector, jumper the 12V connection, ground the return connection (Pin 33) of the regulator. W/ engine running, this should raise the idle quite a bit. Should show around 8 in Hg on the Vac line to the EGR. Max regulator flow. Vac dropping out, unless you also reduced RPM, doesn't sound right. 21 from source is healthy.

Vac did just drop out at egr when I reved it higher. Tested EVR and got 35.4 ohms across terminals. Had B+. Jumped power to evr and grounded pin 33 and got 16 vac at egr but truck did not rev up. It just started running rough and would almost die right away and than caught itself. This leads me to believe the EVR is good and the EGR is not. I also found a coolant leak from the side of the throttle body by the egr. Looked like there are two ports there to coolant passage in throttle body that were filled with silicone and one port was open. Are these suppose to be just filled with silicone?

I'd have to see it. I'll take a look at mine tomorrow.

Its the open hole to the right of the EGR and you can see where coolant is running down.

I just filled the hole. No leaks now.

My other problem would just be a bad egr and not the tube that goes under the manifold?

Thanks