Hi new guy here, im hoping someone can help diagnose this slight engine vibration at idle here is a little background. 2006 f150 fx4 5.4l I bought this truck about a year ago as a project, it ran okay until warmed up then would start shaking vilolently and stalling.
I knew what I was getting into so I ordered up a timing set, guides, tensioners and gaskets, I also did not want to deal with phaser issues so rather than replace the originals I purchased the Livernois lockout kit with the sortware tune. After tearing it down, I found the tensioner seals blown out and the guides and front cover took a bit of a beating from chain slap.
I got all the parts in with new plugs and it runs great (10 months now since repairs) no codes and it is a very reliable truck. Only issue I have is when the truck is first started cold it idle around 750 rpm (normal) after a few minutes it warms up and the idle drops to 550-600 rpm and shakes a little not alot but its there. If I rev it up to 750 it goes away also if i have my foot on the brakes and put it in drive it idles a bit lower 500-550 but is smooth no more shaking. It wont shake or vibrate any other time but at idle warmed up in park. I have looked for vacum leaks checked motor mounts and wonder if this is a fuel related issue. Anyone have any experience with this?

 

In my experience this seems normal for the 5.4. I have a fresh remanufactured engine in mine (14k miles) and it shakes the truck a bit at hot idle. Hot idle on the factory tune is around 512 RPMs, but the gauge reads a little lower than that. It'll run perfectly fine there, but I don't get much help from the power steering system at that engine speed, so i've got it tuned to idle around 550-600 rpm hot with my handheld tuner. Ford sets the idle really low on most of their V8's, so I wouldn't think much of it.

 

Yea I wondered if this is "normal" for the 5.4l I guess the only thing that bothers me is as soon as I put it in gear foot on the brake it smooths right out. I may look into having Ford up the idle a bit or just forget about it as it runs good. Thanks for the reply.

 

I doubt Ford will adjust your hot idle. They pretty useless with stuff like that lol.

Idle speed in gear and in park/neutral is different, that’s why the rattle “goes away” in gear. Just part of the beast.

 

True, but the idle speed drops lower in gear, anyway I was just curious if others have noticed this and it is sounding like they have.

 

yeah it’s lower. Must be below the resonant frequency of the frame I guess. That’s all I can guess lol

 

[QUOTE=Airdrie AMX;5566262]Yea I wondered if this is "normal" for the 5.4l I guess the only thing that bothers me is as soon as I put it in gear foot on the brake it smooths right out. I may look into having Ford up the idle a bit or just forget about it as it runs good. Thanks for the reply.
Yes with these vehicles it does seem to be normal even though it doesnt seem like that would be the case

 

Try turning your wheel at idle, lol
It's natural...they idle low and you'll feel a little shake here and there.

 

Wish mine idled smooth in gear, mine idles rough in, out of gear, hot, cold, dosent matter. Actually gets a little worse when it’s in gear.

 

Mine's like this. Seems worse in reverse, and maybe a little better in park but not by much lol.