I have a 1998 Ford Expedition with a 4.6 liter engine. I am getting a DTC code 401 (insufficient EGR flow). I have replaced the EGR Valve, DPFE sensor, electronic vacuum regulator, and the coolant temperature sensor. This did not take care of my problem.

Does anyone have any suggestions what I might look for next?

 

Sounds like you need to remove the throttle body and the elbow below it has 2 EGR ports that are probobly blocked solid,not to bad to do I did mine in about an hour. On mine the passenger side port was blocked and the one on the drivers side was ok,
You con look through the search under EGR and get instructions and great pics. to do the job.

 

Here's what I did.. and for some reason it worked!?! Use at your own risk!

I took it off and sprayed it out with carb cleaner... put it on, after about 50 miles the light came back on.

Next time I had my manifold off I decided to play with my EGR valve again.. I took it off and hooked up a air compresser blower to it and blew it out.. I think it blew out the diaphram or whatever is in there.. but I haven't gotten the code since and have gone 500 miles.

 

I removed the throttle body and elbow and the two EGR ports were completely clogged . After cleaning the problem is gone

Thanks for all the help.

 

Where you getting a sluggish or sputtering from accelerating (load) on the engine while driving between 30-50 mph. My F-150 1999 4.6L has 169k miles and it was throwing the P0401 code and the P0133. The dealership suggested to change out the DPFE module and that cleared the SES light. But the sluggish sputtering is still there, with some (back fire like sounds when it gets over the sputtering). The EGR is the original, does that effect the fuel delivery while trying to go up hill at 30pmh?

There is no leaking of water/coolant on the spark plugs, they are all dry. The engine runs perfect at idle and general cruising. It just does this after letting up on the throttle and then pressing it down when in that passing speed of 30-50, very prominent on uphill acceleration (gas tank at full).

I will be chaning the fuel filter tonight to see if that changes anything. Then taking a look at the throttle body and vacuum testing the intake gaskets for leaks. It has a new air filter on it.

Any help would be appreciated.

Thanks in advanced.

Jeremy Ferch
1999 F-150 XLT Ext LB 4x2 4.6L 169k miles

 

I have the same "bog" I guess you could call it in my 96 4.9. If you lay in the gas a bit as you are going down the road, about 2000 rpm it seems to fall off for about 500 r's then comes back somewhat strong. Still doesn't feel as strong as I think it should be but it comes back up nonetheless. I replaced the EGR sensor which cleared the mil but still have the problem. I know the fuel pressure is good and just did a fuel filter and cap, rotor, plugs and wires and I just now turned 80,000 on it. Sure would like to hear what ya'll think. Thanks Garry.


1996 F-150 XL 4.9 Auto long bed, dented up, sweating like a hebrew slave work truck. But I like it that way.

 

I keep getting the PO402 code on my egr valve any ideas on how to reslove this.

 

Pulled off the throttle body and just like all the other posts on this board. Both holes were 101% clogged. Having seen how they bored the hole I now see why this happens. They have a poor porting from the long shaft from the EGR valve to the two ports into the elbow. Mine was clogged to the point of the crap sticking 1/4" out of the hole furtherest from the EGR valve. Then it all was backed up past the closer hole (about 1.5") I placed about 3/4 of can of Intake cleaner into the holes (literally tilted the hole assembly to let the stuff sit in there for about 30 minutes) Then came out and dumped it and the whole thing was Whistle clean. (BTW prior to this I replaced the DPFE module which initially cleared the SES light for P0401 and P0133, but did not solve the sputtering)

Took it out for a drive and no more hesitation, sputtering, when going up hills with about 10-20% throttle.

Thank you board for the advice and help

Today officially turned 169,000 on my 1999 Supercab 4x2 4.6L

Jeremy Ferch

 

I had the same problem, turned out to be clogged EGR ports.
Cleaned them out and haven't had any problems yet.