I have a 2005 F150 s-crew 5.4L 47,000KM/29,000MI. When I first start it, I hear a loud ticking noise that goes away when the idle comes down. I hear it again when I accelerate. I was told its either an exhaust leak at the cats or manifold and was also told 2005 models have an extended warranty on injectors due to problems. Dealership wants it on the diagnostic $100 but i told them there are no codes showing up. Any ideas??

 

Where does it sound like the noise is coming from? Front of the engine, back of the engine, middle.
If it is an exhaust leak, it should be more noticeable from underneath.
Cam phasers, I think could be another possibility. What oil are you running in it?
Have you been having to add coolant?
Are there any other symptoms that you may have overlooked.

To eliminate the exhaust, I would crawl under it and look for any rusty places, especially where the exhaust manifold connects to the exhaust pipe.

Another place to start would be to crank it up, while the hood is up. Go to the front of the engine and listen for the noise there, as the cam phasers are at the front of the engine.
I don't think the injectors are the source, but I can't here it running.

 

I have a similar issue. Can only hear it when on the throttle. I put an aftermarket exhaust a while back so checked all that made sure it was tight. But it sounds like its coming from the passengers side of the motor. It's pretty load. Also I have an 05 f150 with the 5.4(31,000miles).
I know it's not the cam phasers.

 

Its coming from the back of the engine, underneath and passenger side. no other symptoms and I use 5W20 motor oil. thanks for the reply

 

I have the same noise in the same location. Has been there for awhile, so if you find out, let me know. One mechanic said drive until it breaks and then fix. He did not seem too worried about it. Local dealer head mechanic didn't say anything about it when I took it in to get a couple of keys. I asked him, but he said he didn't notice anything unusual. Could the cats be rattling on an '04?

 

my neighbour has an 04 and had to replace his cats, they had issues with the 04's, mine are not rattleing, will let you know when I get an answer