So last August I got the CEL, pulled the codes, excessive EGR flow (or insufficient, don't remember now). Talked to a mechanic buddy who worked at the Ford house for a long time. He said the DPFE sensor was most likely at fault. (Same thing on my mom's 4.6L went out several years ago) Cool thing was that my mom had a new one still in her truck as she bought it then realized Ford would replace it for free for her for some reason, so she kept the one she bought in her truck. I swapped it on, and the truck was fine for about a month. Then started getting the same codes and low rpm surging. So I figured must notta been the DPFE sensor, but no sweat since I didn't hafta pay for one. So I put a new EGR valve on it, and it was alright for another month, but then it started doing it again. Went to the parts store and the guy at the counter told me I needed to clean out the EGR tube that runs from the manifold to the valve. So I pulled the EGR valve off and per his instructions started the motor with the tube venting to atmosphere to hopefully blow out any crud that may have built up ANYWAY, that didn't do anything, and while the truck runs fine, the CEL comes on about once a month or so for a few days and the surging gets really irritating. Then it goes off and runs fine again. But I'm SICK of the CEL coming on but am stumped as to what it could be since I have a new EGR valve AND DPFE sensor. Any ideas?

 

Ge4t the codes again and tell us what it is we need to know them to help Autozone does it for free

 

Last time I had the dpfe code it was the tube that runs into the exhaust manifold. reemed it out and it went away. I never had a surging though. The truck ran fine. Get the actual code number and come back.

 

what brand dpfe and egr do you have on the truck? did you check the hoses to the dpfe?

 

UPDATE: Got the codes pulled. P0402 - Excesive EGR flow.

jethat: what did you use to reem out the EGR tube? I picked up a small wire brush that I was thinking I could attach to something (maybe a clothes hanger) to reem it out with, but was curious how you did it.

Matts ford: IIRC, both parts are motorcraft. Been awhile since I put them on though, so I'm not positive.

 

I hate little nagging problems like that, so if I was in your situation I would go ahead and throw another DPFE on there since you're unsure of the origin of the one you have and that should eliminate one possibility. I'd look at it as you will eventually need another one anyway if the one you have now is good, they're relatively cheap, and that's the most likely source of the problem.

Good luck, and let us know what you find out.

 

Well, your mom had a 4.6L , -that's nice. But what engine are we talking about here?

402 is poppet valve failure. That's the valve that opens/closes at cruising speeds and overall betters your economy.



Like Queso suggests, I've seen the the DPFE throw that code BUT, the code could also be legit w/locked poppet or faulty diaphragm. Here's what you can do to narrow it down, eliminating a possible valve and throttle body port problem. Whatcha do to test- Disconnect the green line (EVR line) from the valve. Connect your own line (3' scrap line) and suck on the line like your drinking a milkshake while @ idle. If the vehicle almost stalls - Poppet valve is ****ioning/ports MUST BE clear/ - DPFE needs to be replaced w/dealership part only.

EGR/Emissions Problems ? Head over here for a little knowhow - http://www.fordscorpio.co.uk/egrmonitor.htm

 

Queso, thanks, but I don't exactly have money to just throw at parts :o Need narrow down the possibilities before I buy anything.

jbrew, mine is a 5.4 if that makes a difference. Thanks for the diagram and tips. I'll try and find some vacuum line or something similar lying around here, otherwise I'll hafta go and pick some up next time I'm in town. Probably be wednesday before I can get to that. I'll post up results when I know.

 

It does. Always list that so we know how to answer.

 

Will do, thought I had but guess I forgot to.

Found some fuel line that fit on the EGR valve, hooked it up and the motor wanted to die when i sucked on the hose at idle. Your previous post seems to have disappeared however, so I don't really know what that tells me lol.

 

Good job! It did? Oh - One minute

EDIT:

Fixed

 

ah cool, thanks! Looks like the DPFE after all huh? Bummer, I thought I had really lucked out when I got that free one lol. Thanks for the help, and the crazy fast replies! I'll try and pick up a DPFE sensor this week and report back after I have new results.

 

Well, before that, - wouldn't hurt to go over the vac line harness real quick. This supplies the vac (suction) to open the EGR valve upon PCM command. Make sure the VAC(air) lines aren't damaged. The dealership DPFE Sensor is pricey, -unfortunately you their replacement part. Third party DPFE Sensors either don't work or fail in the near future.

You may have a damaged EVR elec connector (highly unlikely, but possible). Inspect for obvious damage.

The vac harness isn't usually the problem, but has been in some cases. Check green and white lines, - The plug in trunk is between the battery and firewall. I've seen damaged lines in that location in the past. Here's a pic of the harness (better pics in gallery/ linked below) -



This diagram ^^^^^ should be on the cowel under the hood.



Vacuum line gallery, more pics -

https://www.f150online.com/forums/me...uum-lines.html

Good Luck.

 

I understand, and it's not like we were just shotgunning it, we are working on an educated guess here anyway based on the information you gave earlier. Glad others have joined the discussion and you have more information with which to make your final determination.