Check for plugging downstream of the EGR valve. This picture shows just how bad it can be. Both me (98 expedition) 110k and my brother in law (98 F150) had same problem. Codes showed low EGR flow. Tried all the suggestions first, bought new DPFE switches, Cleaned EGR valve and exhaust manifold tube, etc. All the time it was this simple ugly plugging. Carbon buildup relative easy to clean after removing throttle body, don't think you can unplug without removing throttle body.

A business card is inserted in TB so you can see black sludge ball. There are two one for each port and there shadows on the card. Passage ways totally plugged. Used coat hanger to clean.

 

AggieMike; Just out of couriousity what type of symptoms were you dealing with before you had to do this? now this does look famialiar to me with my 97 expedition 4.6, but the 98 that we have now has a 5.4 & the throttle bodies are just a little different
between the two. I think that I will be looking in to ths on my 5.4
soon to see if this is also the case with it also.
keep us posted turbo ted

 

Check engine light comes on and stays, trouble code for EGR low flow. Can't get car emissions inspection until code cleared. I got Autozone to clear code and raced to the inspection place before light came on last time! Don't really notice a performance problem the plugging just means you have no EGR.

 

I had the same situation...was getting PO401...pulled the EGR valve off and it was probably the cleanest one I've ever seen, but thanks to Aggie's post I knew to keep going...pulled the TB off and had goobers like shown in Aggies's picture....reading this forum last night before starting the work today saved me a bunch of time, and probably money, cause I wouldn't have pulled the TB off if I hadn't read that post, I'd have gone looking elsewhere for the problem....

So thanks, Aggie, and thanks FTE for a great source of practical information...

BTW, when cleaning out the TB ports, a 27/64 drill bit worked thru by hand with a pair of vise grips does a nice job of clearing our the junk.

ps

 

First post, mostly been lurking...

1998 Expedition, CEL comes on (actually has been on for a year). Last year it passed emissions but the guy told my wife "You are going to need a new gas cap soon." A day later, CEL! I replaced the gas cap, stayed on. About a month later, it shuts off. Two days later, back on. Bought the EZ-Scan 4000 scanner and it had a P1401 code( this is recently as it's time for emissions testing again). Cleared the code, took off the EGR and cleaned the heck out of it. She went for emissions, failed (Hadn't passed the readiness tests yet). On her way home, CEL, P1401. After reading here I went and bought a new DPFE sensor (metal one) and installed it. Re-scanned, gives me a Failed $41 - "Delta Pressure for Upstream Hose Test" So I look at motorcrafts site, and I go buy a new EGR valve and a new EVR. Take it all apart, remove the TBA and the ports are clogged solid like. I clean them out very well, install the new EGR and EVR. Put it all back together, crank her up and I get the Failed $41 again AND a failed $22 "Leak Check Vacuum Bleedup" AND a pending P0401.

What else can it be?

Cptn
98 Expedition
98k miles
City/Atlanta/Traffic/nightmarish/Driving

 

I have a 98 F150 4.6 I was getting a code of p.o. 401 low egr flow,after reading about it here,and talking to my ford dealer the awnser was to clean out the carbon,and replace the vac. solinoid and the E.G.R. pres. sens. after that all failed I found there was no supply of vac. to the switch,so I traced it and found my O.E.M. battery had leaked acid onto the vacume hose loom and ruened half of them on bolth sides of the pig tail.

 

I checked Vacuum, seems fine... Well, at least there is vacuum, I didn't check it with any type of vacuum gauges or tool...

 

OK, no codes so far but it hasn't completed its readiness tests for the Evaporative and Catalyst tests. Anyone know what the drive cycles for these are?


Thanks