Hello,
I have no idea what could be causing this. I have around 150000 miles on my truck and other that that I have not had any issues with it. And now since around mid-January I’ve got intermittent P0401. It comes for around 60-70 miles and disappears for a couple of days or weeks and then comes back for another 60-70 miles.
So I’ve changed DPFE sensor and EGR valve… no luck
I cannot make the engine to start stalling if I start sucking onto the EGR valve's top port but there is a vacuum on the white line on DGFE sensor and a little bit smaller vacuum on the green line on the top of the EGR valve.
I read that I am supposed to clean the EGR ports on the intake manifold but I don’t want to do it by myself (scared) and the guy at the service told that he never had a truck that required the clean up. He tells that it’s vacuum lines…
I think that SeaFoam would not clean the ports, right?
Guys, what is that?! It’s so annoying…. What should I do??
Why it's intermittant?
Thanks, Alex.

 

If you cant kill the engine by applying vacuum to the egr,, with mouth or pump,, then most likely you have clogged ports.. Clogged ports are common causes for 401 in the 4.6's.

 

864Lightning,
Why would it be intermittent then?
It bugs me...
Thanks, Alex.

 

I had the same problem in my vic carbon was partially blocking the ports causing intermittent blockages. I cleaned it right out and p401 has yet to come back

 

Ok,
Is there a way to clean up the ports without taking intake manifold off?
Any ideas?
Thanks, Alex.

 

I did a little searching and found a thread that has a picture and addresses the 4.6 clogged ports,,, It looks like you have to unbolt the throttle body and then remove the turndown elbow that bolts to the manifold, this is where the ports are and from the looks of it I wouldnt want to try cleaning it with the elbow on the engine.. Those are some big chunks of gunk and I wouldnt want them falling into the intake.

I did the same thing to my 5.4 , but I found the 5.4 has one huge port and doesnt suffer from the clogging like the 4.6 has with its two small one.
It was really an easy job to remove the elbow on my 5.4,, nothing compared to changing the dang sparkplugs!!

Here is the link to the thread

https://www.f150online.com/forums/sh...+ports+picture

clogged ports picture is what I searched on that returned this thread as one of the results.

hope this helps

 

my birds 4.6 required a new dpfe i saw the pid values it was stuck at .14 volts. then light came back on. so i cleaned the ports they were full to the top with carbon. when i pulled vacumn on egr it would start to miss so i figured everything was good. drove it hard for acouple hours parked it next day light came on ended up replacing the egr valve also was all gumbed up made it sticky when it would get hot and then let it cool.

replacing the egr on a 4.6 bird is not a fun thing to do on a saturday. hope its easier on a truck.

 

Thanks guys!
I appreciate your input very much.
I am going to take the truck to the mechanic on Thursday and will follow up after that.
Alex.

 

Hello,
Here is promised update.
Went to a mechanic to clean up the EGR ports - did that...
The code is back in 30-40 miles.
Bought new vacuum regulator - the code is back in 30-40 mils.
So now I have the ports cleaned, new EGR valve, new DPFE sensor, new vacuum regulator and still the code
The only old stuff is the vacuum lines....
Could you please guys tell if I need to look at the vacuum lines which one would it be?
Any chance the ECU is going down? Any chances on that?
Why do I have the code?
Please anything would be highly appreciated.
Alex.

 

one more thing to check,,, the plastic vacuum lines are bad to rot and crack right behind the battery,,, one of the lines is the supply for the vacuum regulator that controls the egr valve. A simple check is with the engine running, pull the vacuum connector off of the regulator module and use your finger and feel for vac on the plug,, one of the lines will have strong vacuum ,, enough to suck a red spot on the end of your finger.. If you have a vac gauge you can use that,, I am not sure of the specs.. The other line is the control to the top of the egr valve and wont have any vacuum on it.

I found cracked lines on my 5.4,, you could just barely feel vacuum at the connector.

Good luck,,, sounds like you are having a rough go with it.