From the day I picked up the truck at idle it always seemed to shake more than I have had on my 2000 4.2. this is a 05 4.6. No other issues just wondering if anyone else has noticed the same.

 

Mine does a little tremor at idle, you can barely feel it through the seat. I've heard others report this as well so I think it's mostly normal. I'd like to hear from others though.

 

Nobody?

 

How many miles are on the engine? What type of gas do you use? Cheap gas can cause the injectors to clog, causing a poor spray pattern, resulting in a rough idle.

The plugs could also be overdue for a plug change. If the spark plug gap gets too wide (electrode wear), this could be your cause of a rough idle.

Buy some injector cleaner; add it to your gas tank the next time you fill up. Do this a couple of tank fulls to see if it helps.

 

My 05 FX4 does the same thing from time to time with 80k on the clock. I have driven a few newer rigs with lower mileage and they seem to do the same. I've always just figured it to be a pretty normal thing. I'm planning on doing a tune-up soon. Maybe that will fix the problem.

 

try cleaning the throttle body as well....my fx4 used to have a rough idle that would dip at times as well as cause a vibration and once i cleaned the Throttle body out it has been running like new....

 

For me, 56k miles. I use good gas, only from QuikTrip. I'm going to change my plugs here shortly. I'm not very worried about it, you have to actually try to notice it since it's so slight.

 

I say give it a couple of shots of jack...and she be fine

 

Mine rumbles bad. It isn't a misfire. I've cleaned the TB replaced the plugs and ran injector cleaner several times. I've driven a few 4.6l and one other 5.4 that were CLOSE to the same but not as bad. With the A/C on and warmed up the thing FEELS like it idles higher and rougher but it doesn't ever feel like it's going to die or like it is misfiring.

 

Mine does it to ever since the day i picked it up in 08! no dip in rpm but you def can feel it. The dealer told it was nothing. Only use quiktrip fuel tryed lucas additives helped a lil but not much. Has 46k miles & it hasnt got any worse so yea.