2000 f150, super cab, 2wd, 4.6 with 200k. I got it from a buddy that was going to donate it since it had a blown plug. I got the cal van kit and got the #7 cylinder all fixed. Started the truck and it was running really rough (like it had the worlds biggest cam).

So I started swapped the coil pack from a different cylinder and no change. Messing with other things I pulled the vacuumed line off the ERG and it smoothed right out and was purring like a kitten. My buddy blew some compressed air in the EGR valve and it made kind of a POP sound and some dust came out. Hooked it back up and still ran fine. Ran it a few miles and everything was good UNTIL.... the next morning I fired it up and was running crappy again. No check engine light but had 2 pending codes. P0401 (EGR) and P0455 (evap crap). After a few miles on the interstate everything smoothed out and ran great. Even at a stop and low RPM’s. 25 min drive and then got home and shut her off for a few. Started it back up and running crappy again. Installed a NEW EGR valve and still the same stuff. Did the whole “computer re-learn” and no change. I’m starting to get stumped here. Any thoughts? Thanks gents

 

Check the DPFE unit and the hoses going to it. The 401 code, is usually that the DPFE is the culprit and the first thing on the check list.

 

i will check that tomorrow. Would that make it run good at times and crappy other times?

 

What possessed you to blow air into the EGR valve lol. Doesn't matter now, but it's blown now. That pop was the diaphragm exploding. Yea the valve in non serviceable. There's nothing you can do to service that part.

Pulling the green line like you did, then the engine smoothing out proved you have an EVR problem.

BUT, none of that matters now since you blew the diaphragm. Without the diaphragm the system is permanently closed. The good thing with all that, yes , you'll get a 401 DTC, but there will be NO drivability issues. This has nothing to do with the way the engine runs now. You took it out of the loop and it's now disabled. It can't cause problems now. Look elsewhere, it's not the EGR now, but it was. In essence you did a good thing in away...by destroying the valve lol.

 

Lol, how loud did it pop ? I recall one user mentioning in the past he use to pop old valves in the shop behind someone, said it was just like a firecracker lol.

Anyway, if you installed a new EGR valve, the problem will reappear IF you connected the green line back up. That's because the original problem (the EVR) becomes relevant again. The EVR will hold the valve open which inturn causes the engine to gage on burnt exhaust gases being sucked through the plenum re-entering the combustion chamber. They can't run that way. It would be like someone relieving themselves into your oxygen bottle...how well would you run?

So yea, if the EVR is still bad, the new EGR valve is creating a problem again. Disconnect the green line again until the EVR is dealt with or it will not run very good if at all. Understand that it's not the valves fault, never was, it's a bad EVR or possibly a bad command from the PCM. First try cleaning the EVR filter. That filter (if packed with dirt) will cause the issue. That's because the EVR cannot cut flow to the valve and PCM command is moreless ignored or subjugated. Pop that cap, clean it.

If the Search this forum wasn't so terrible on this site, I could direct you to a recent vid post a user recently posted up. He posted on Oct 13 2017 and it was in reference to PO402 problems, but I can't find the post. A PO402 is the code you SHOULD have gotten but it doesn't always happen. A PO401 is more of a generic code, the 402 is a more of an identifying code. Regardless and because you pulled the green line while troubleshooting you have with a doubt proved a 402 error. This is what have and what you should treat it as.

Hopefully User AK or someone else can find this post for you. This guy puts out troubleshooting vids and posted here on the date given. Really wanted to find it, he is the first user I've seen troubleshoot this correctly and very well. Showed the fix as well. Can't believe it can't be found already...it's new lol. I searched PO402 here (forum tools).

Well hang on, it was You Tube, I'll try there real quick..... Found it, it was Ozz that posted it, this is your problem -


It's what you need to do. Otherwise you will continue to have a major problem. Now I'm not sure this is the extent of your problems. However it is a major one that will continue if you don't address what's causing it, ie the EVR. Fix this first before moving on to other problems. Here's a diagram I posted for Ozz's thread. It shows the EVR in relation to the EGR. When you removed the green line you canceled the EVR therefor shutting the valve in the EGR. You posted a change in idle, the vehicle ran better. Proof of the 402 fault...bet you didn't know that before. That's how you identify the problem quickly lol.

 

FWIW, when I got P0402 code, it was the EVR that was bad. It was accompanied by P1409 as well....