Hello, my 2006 5.4l just turned 70k. I have a question on what a smooth idle feels like with this truck. I'll list below what all I had done to it but when you are idling, either in gear or park, do you feel any sense the slightest shimmy/shake feeling in the seat of your pants? I had the plugs/coils changed, MAF/throttle body cleaned, new fuel/air filter and ran some amsoil fuel cleaner through it and use technron gas. It still feels the same as before I did all of those things which makes me wonder if that is normal? its not a rough idle by any means, the engine is super quiet and smooth but when stopped at an idle, about every 3-4 seconds I get that very slight sense of a shimmy through the seat. other than that, you would barely know the engine was on.
any thoughts? thanks

PS, no codes being thrown etc. did have some misfire codes but the plug/coil change fixed that.. Use motorcraft plugs, accel coils, recent oil change etc. before I had all of that work done it idled exactly the same way.

 

Assuming it's somewhat normal to experience the slight shake every few seconds? I have no other truck to compare it to. Seems that it's common on the 4.6 but can't find much on 5.4 3v.

 

I sometimes have a perfectly smooth idle and sometimes also get the slightly rough idle every few seconds like you do. The motor has 211k on it. I think new motor mounts would really make a difference but, from what I have read, changing the motor mounts is a very big job so I will just live with it.

 

My 08 with 66K don't shake...

 

I'd check your exhaust mounts and muffler. My Jeep had a faint shake at idle for 10k miles until I replaced the muffler.

 

thanks for the feeback..

 

thanks, everything is tight/solid as can be down there. I recently had muffler changed but it did the same thing before and after.

 

I took mine to the dealer when it had 24k because I felt the idle wasn't as smooth as it should be for a V8. They told me it was a characteristic of the engine, that's the way they run. Mine is fairly smooth in park but when in gear especially with the AC off,it has a crappy idle for a V8.

 

Hi, you have the 5.4l 3 valve?

 

yes