Going to the dealership in a week but just curious what it could be. Truck is rough idling when in park and motor is warm and it also has a knock to it. Been doing it for a few months now. Kinda reminds me some what of a diesel motor sound. Only does it when motor is warmed up and at idle. I was told cam phasers but I thought that was only 2004 and up. Mine is an 03 5.4, oil pressure good, gas mileage seems normal, and no SES light.

 

Could be a lot of things sounds like maybe your getting some piston slap?? WAG

1st thing I would do is check the spark plugs and make sure that your torqued to 28 ft/lbs. Unless you have not replaced the spark plugs for some time and the mileage on your truck dictates that its time...then by all means a fresh set of spark plugs is a good start.

yes you are correct...cam phasers started with the 3v engines. Yours is a 2v engine, there by, no cam phasers.

How was oil pressure checked?? Just from the one on the dash ?? I would not trust the factory dash gauge , it is just a glorified Idiot light & only requires 7-8 PSI to activate it. You need to have a mechanical oil pressure gauge placed on it to get accurate PSI readings. You can request it when it goes in.

you can also have the exhaust manifold checked for cracks...this also can produce a knocking sound.

 

The truck has 118,000 miles on it and my local delarship did the plugs at 100,000. Yeah just the gauge on the dash is all I watch. If I just barely and I mean barely touch the gas pedal the knock sound goes away. Other than the knock sound truck runs totally normal. No smoke, doesn't burn hardly any oil at all. Gas mileage is the same as always. Been doing things prolly atleast 6 months.

 

Maintenance history? What oil and filter?

Could be something like an exhaust leak... timing chain/tensioner, bearing noise, cat/heat shield, injector noise, loose plug or even something simple like a pulley.

your going to pay $150 just for a visual inspection at the dealer. Might as well do that yourself and try to pin point it. Pick up a mechanics stethoscope and narrow down where the noise is coming from. Video always helps if that is possible. Some of us can tell just by the sound and rhythm whether is is valve train, bearing etc..
By your description of a dieseling sound, it could be a bearing

 

Still wouldn't hurt to have the torque on the spark plugs rechecked. Just to make sure type of thing. AS mentioned earlier, It certainly couldn't hurt to check the oil pressure with a mechanical gauge under this warm idle condition...if nothing else you get a clearer idea of the physical condition of your truck. And check the exhaust manifolds for cracks.

If A slight pick up of RPM clears it up, it maybe nothing too serious, mine kinda does the same thing from time to time.

You might have a slight vacuum leak to which has been known to happen on these. Also it maybe due to get the throttle body housing cleaned up along with the IAC. Cleaning the IAC maybe will help with the rough idling. especially if you have not done so yet.

What kind of Oil filter are you using....Fram is notorious for quality issues

 

I purchased the truck with 88,000 miles on it and it now has 118,000 and the ford dealer has done all work and general maintenance on it since I have owned it. It sounds and acts just like the 3v 5.4's do when they have those cam phaser issues.

 

I'll mention them doing that. Ford dealer does the oil changes on it. They only use motorcraft parts and oil.