rydered

Hey guys. I'm having a problem with rough idle in park when warmed up. 06 fx4 5.4. Idles around 590-610 rpm. I've had all new cloyes timing gear done. New plugs (sp515). New coil boots, new vct solenoids, new fpdm, cleaned maf and throttle body. When in idle and warmed up the truck has a noticeable rough idle. The seats shake and stuff in the cup holders will shake also. But if I put it in gear or rev up a little bit it ends up smoothing out. What do you guys think? This is really bothering me!

rydered

Bump

4.6F150

x2 mine idles like complete s#!t, but mine also runs like crap when it planes out to speed it gets a rough idle when I try to get on it, just had the spark plugs and coil replaced because one cat got plugged, heated up, and fried all of that. Not sure if the replacement plugs have something to do with it but I have a feeling it's a fuel delivery issue, not sure any help would be appreciated

corey_lax

Change the fuel filter, air filter and replace the gasket on the airbox as it has probably deteriorated.

Start with the cheap and easy and see if it helps out...

rydered

Actually I already did all that. I am gonna change my fuel filter again tonight.

powerranger262

Don't mean to get off track here, but what is the recommended mileage to change your fuel filter at?

rydered

Believe it's 25k-30k

primalurges

I've had the rough idle for over 80k miles. Mine Is more pronounced when its in hear with the AC off. I've been in 4 cylinder cars that have a smoother idle. Took it to dealer while it was still under warranty and they wouldn't touch it, said it was the characteristics of the 5.4 Triton 3valve. My truck is an 04. I've given up on the rough idle and just live with it.

Masi1926

Sounds like one of three things-a loose plug or coil, or maybe a coil boot is cracked. 95% of the time it's a plug that loosened back up after a plug change.
I double checked mine and even after that, one came loose a couple days later.

rydered

I checked the plugs. There all tight. Boots were good and coils were good. I also cleaned the mass air flow sensor again and changed the fuel filter again last night with motorcraft. Still have the rough idle