Replace the PCV with a dealer one, the aftermarket ones are known to leak, they basically work like a faulty OE one. The cost is not great, there are just some parts that aren't worth screwing around with.

 

Got a new Motorcraft PCV valve... I was able to blow thru it in both directions also... This isn't normal from my past experiences... Put it in anyway, and noise is still there.
Double-checked hose running from PCV valve to back of intake. If I remove the hose from the PCV valve, the noise goes away. If I put my thumb on the end, it will make the sound before killing the engine.
Is it common for Motorcraft PCV valves to be defective when new?

 

hi i bought a cheapy one about $2 to try i couldnt blow through in both directions it didnt solve the problem but i may buy a dealer one soon

 

I called around, and found a Ford dealer who had another PCV valve. I asked hime kindly if he'd check to see if he could blow thru the PCV valve in each direction. At first he said yes, he could... Then he said he tried it holding it vertically, and couldn't blow thru in both directions. I pulled mine back out and tried that, and could stil blow thru both ways... O'Reilly's is getting another PCV valve in this afternoon. UGH!

 

well once again i have checked every hose in the engine compartment and all the hose's hold pressure and i replaced the pcv hose elbows (they looked old and cracked i then drove it a few times not far and the light come back on with the same codes i was told by a friend that i may have a intake manifold leak i have searched all week for vacuum hose leaks ,, i know i have a few old cracked looking hoses around my fuel tank
what do you guys think

wilky

 

I would lean towards the intake gaskets as well

 

well i just checked the vacuum pressure with my neighbour whos a mechanic and he said the vacuum pressure was almost perfect and didnt move a bit
checked EGR valve he said it may be dirty injectors that need cleaning or a bad fuel regulator or pump i was thinking about going and buying/borrowing a gauge to check the fuel pressure

is there any truth in these possibly beeing the cause or should i go ahead and replace the intake gaskets

i need the truck fixing in the next 2 weeks as i plan on useing it to hunt

many thanks wilky

 

check the vacuum lines that run to the rear of the truck to the gas tank for the evap system. should be rubber, then going to a steel line to the back, then rubber to the tank. Check the steel line for spots of rust through and possibly rubbed through.

 

well i booked it in for a 4 stage fuel system cleaning tommorow evening it is only $109.99 at pep boys thought it cant do any harm and it will need it as it has 174k on it and is unlikely to have ever had one before

 

As noted in the similar thread "loud humming noise coming thru intake"
I put my old IAC back on, and the noise went away. Turns out all of this was likely because of that one hose elbow on the back of the intake on my truck... Looked over all the lines going back to the tank too, and they look dirty, but not rusted.

 

Well I went and got my fuel system cleaned by pep boys and it runs rough really rough to be honest never ran like this before I am takeing it back tonight to be fixed they messed up somehow I don't recomend pep boys work at all never going back there again I just hope they fix my truck tonight

 

Well pep boys are coplete idiots they said a mechanic inspected my truck and cylinder 4 wasn't responding and the fuel cleaning in no way could have affected my trucks running so I have took it to my ford dealership for diagnosis and they told me they could have very well messed up the running of my truck they have had it 2 days now and called me asking who did the fuel cleaning as it looked as if a kid had done it I have to wait till monday for a full report as they are investigating the fuel system further I am in discussions with pep boys about reimbursing my costs and compensation for there incompetence just never go to pep boys how ever cheap they are its just not worth it but the bright side is I may find out what's causing my lean codes

 

I am finally getting my truck back I had 2 coils out and needed a new fuel pump as it was only putting out around 13PSI it also needs new spark plugs in the future so I will have them done when I next get paid then all ill need are new tires and I'm set for winter

 

I'm knocking the dust off of this thread. I've searched this forum high and low for this situation. Even tho the OP found his problem, I've been dealing with the same codes and symptoms for two years. But on mine it only happens below 35*. I've chased this and that, checked this and that, including all that's mentioned in here with no luck. I have researched and thought and tested over and over with no luck. Until today. I thought maybe since it was ambient temperature related, what could possibly be connected to that. Then it hit me. The air intake temp sensor. I just got one for $15 and my truck is idling smooth as silk in 30* weather. We will see if it keeps up when the snow comes in a few days. I hope this helps any other head scratchers like me.

 

I am glad you knocked the dust off this thread...

Im runnin lean and searching the site. This is the wrong gen 5.4 for my application, but some good trouble shooting tips