With the engine under normal loads of the truck, any time I let off the gas I hear this odd harmonic burble/gurgle from the engine. I have heard it with the truck sitting still and me revving it from under the hood but not nearly enough to be able to pick it up on a video. I noticed it more once I put on my K&N filter so I am lead to believe that this is something intake related. Possibly the PCV valve? IDK...

Any input or experience would be appreciated.

(Oh, its a 2002 4.6L)

 

Oh, and just before I noted this noise it was/is throwing a "Bank 1 too lean" code. I think it was Bank 1... I cant remember. I dismissed is since it was running/driving ok.

 

exhaust donut? my 97 put out a similiar code n thats what it was

 

During idle the vacuum level is about 18 inches.
When you add throttle, the vacuum level goes down. when you suddenly close the throttle from a higher rpm, the vacuum can go as high as 22 inches.
This amount is 'SUCKING" open a hose at some point in the intake system or a solenoid is leaking under the higher vacuum level until it falls back to normal.
Look hard and you should find it.
It will set the code you last saw, if bad enough a leak.
Good luck.

 

Well... that's alot of hoses to check back there behind the intake. Gonna need a couple beers first. Haha.

I just replaced the large hose that goes from the passengers valve cover to the rear of the intake due to collapse about two weeks ago... if anything the noise got a little more noticable after that. I was kinda hoping it was that hose causing the noise.

 

Did you also replace the 90 degree elbow on the PCV line at the back of the manifold?

 

Yes... both peices came with the new line. I got the $37 part from the Ford dealer. Both ends were of a new design so as to not collapse as easily under so much pressure.

One thing I didnt replace was the PCV valve... I could not find it anywhere. I got a replacement from O'Reilly's but again, could not locate it.

 

Only use a Motorcraft PCV valve. It's a EV258 and Rock Auto has them for about 10 bucks.

 

Can someone take a pic of their PCV valve placement? I can not locate mine.