My buddy has a 02 5.4 with 146k on it.. Couple weeks ago it started idling rough at idle, jumping from 5 to 800 rpm sounds just like a big block with a big cam in it.. We have replaced the Egr with a new one from Advance and still did the same thing.. I did find out if i unplugged the vacuum line on top of the egr that the truck would run perfect, as soon as we plugged in the vaccum line back to the egr then the rough idle would return.

We also cleaned the TB, and the EGR ports

Since he bought the new Egr we figured it would be worth it to replace the DPFE sensor, still did the same thing, changed the vaccum selonoid and same thing. Replaced ALL vacuum lines under hood and still does the same (including the pvc line) He then went and bought a MotorCraft Egr and put it on and still does the same thing.. Only code showing is the p0403.

Let me add that sometimes after putting the new egrs on it would run good for a while ( around 50 miles) and then start doing the same thing.. Today after putting the new motorcraft egr on it was running like total crap.. He put the original on and right now the truck is running great again, but its only a matter of time until it starts sounding like a cammed big block again

Any Idea's???

 

Here is what I get out of your post.
First the 403 code does not apply to an 02 F150.
This code is for a stepper EGR system the truck does not have unless it is equipped differently from a standard production.
Re check for the code.
Next you are indicating the EGR is being held open for some reason.
The only way it gets vacuum is through the EVR.
Is the EVR stuck open, is it connected incorrectly to pass vacuum when it should not?
If the motor runs right with the hose off the EGR, that's the issue.
The code, when correct, is telling you the same thing and likely is 402 not 403.
Good luck.

 

Im 100 percent positive its a po403 code, ive scanned it 20 times in the last 2 weeks.

What is the EVR?

 

OK i googled the EVR and it shows to be a Electronic Vaccum Regulator.. Which is what i called the vacuum solenoid which has been replaced with all the other parts.

 

Does the idle return to normal with the hose off the EGR?
If yes, the EGR is being held open.
Check for vacuum on the end of the hose that should not be there to any large degree.
When this happens exhaust gas flows into the intake contaminating the normal mixture and ignition timing advances some causing the roughness.
Good luck.

 

95 percent of the time it does return to normal with the hose off the egr. There is Vacuum on the end of the hose always.. Its enough to where if you stick your finger on it it will stick to your finger.

I read the reviews on the EVR from Advance that he bought and they are pretty much Crap. Have a feeling he got a bad one. Would you suggest a new Motorcraft EVR? Its hard around here to get MC parts cause the dealer marks up the prices about 75 to 100 percent. My buddy isnt the type to wait on parts, so therefore he doesnt like ordering from the internet and having to wait a week for the part to get here.

Thanks for your Help,

 

You pretty much proved the cause.
I would try the used part yard for one.
Clean it with throttle body spray before installing to be sure it's operation is free.
.
The only time vacuum should be present to the EGR is in third or OD at light throttle in the speed range the PCM calls it to operate or during a test of the system when it pulses the EVR to regulate the flow requirement for the test..
The valve is a 3 port device. When operated it passes vacuum to the EGR.
When released, it opens the EGR to air once the EGR has operated because it will hang the EGR open too long if not. The EGR is a passive device, otherwise.
Good luck.