'99 5.0 - Surging idle & P0401 Trouble Code. Need help!

[Thallarsen]

After my '91 was totaled by a Daewoo (!):roll:, I just got a 5.0 Limited AWD in near mint condition.
Much more refined than my '91 as I would expect....not as much of a truck.
Anyway, the P.O. mentioned that the CEL had come on, and he'd taken it in to the shop & got an EGR related code. The shop replaced the 'EGR solenoid' according to the receipt.
After heading down the road, the CEL came on at moderate..not highway speed. It stayed on for the rest of my 4 hr. trip. During the trip, I stopped for gas and noticed that the idle was surging a bit. Not sounding like misfiring, but more a 100 rpm surge, as though the a/c compressor was kicking on & off (defrost wasn't on). I also noticed a bit of stumbling during light acceleration.
Yesterday, I took it to a local shop (same franchise as the p.o.'s shop) and had them run a diagnostic.
They came up with P0401, which says "Insufficient EGR flow detected".
That's all I could get from them. They reset the CEL and it's stayed off for the last 20 miles or so.
I'm expecting it to come on again...I just have a hunch. The stumbling at acceleration seems a bit better, but the idle surging is still there.
Any ideas as to what's causing this?
Also, what are the disadvantages to AWD as opposed to 4WD - aside from 4 low capability?

Thanks,
J.P.

 

[BradE.]

According to Ford Factory Service your code could be caused by damaged vac lines, EGR itself has failed, EGR Valve position sensor or EGR Vacuum Regulator Solenoid.

 

[mrboyle]

From the info in your post it sounds to me like the EGR valve is sticking. This is not uncommon.

 

[Robb]

Your DPFE is bad. 90% chance.

 

[Thallarsen]

Thanks for the posts! Like I suspected, the light's on again...only after 25 miles or so.
mrboyle: Is the EGR valve the same as the EGR solenoid, or are they separate components (I haven't gotten a shop manual yet, and I'm new to this engine). When I bought the car, the seller showed me a receipt showing that the shop had replaced the EGR solenoid. Any links related to this specifically?
Morrisey0: What & where is the DPFE & what does it do? Any links that come to mind?

J.P.

 

[Robb]

I got the 401 code on my old F150 (4.6) and my dad's Expe (5.4), both turned out to be the DPFE.

From reading here on the boards, the 401 code pops up usually when one of two things are bad, the EGR itself or the DPFE. Majority of the time, people replace the EGR and the CEL continues to stay on. Most of these situations turn out to be the DPFE that is bad.

The DPFE is the.............um..........."differential pressure feedback egr"........I think. I always forget what the "E" stands for. Basically, it is the sensor telling your EGR what to do. If it goes bad, your EGR will stick too far open or closed, therefore throwing the CEL.

Any links? I am not sure of any. I am pretty sure if you search for DPFE or code 401 (0401), you will come up with some more info.

Good Luck!

Robb

 

[Majisto]

I had a code similar to this and I unplugged the battery and the CEL went off and the code was gone Guess it was just a bad tank of gas. Check to make sure your gas cap is on too. I had a CEL come on once because of that