All: Just registered to this forum hopeful for help. I have a 06 f-150 4x4...124,xxx miles on her. I pull a ranger fishing boat a lot with this truck and am having vibration problems as of late. I have taken it to a tranny shop and no codes are thrown for tranny and they said it looks great, rear end is great, bearing etc are great. No codes found for plugs being fouled either.

What happens is whenever I accelerate from a stop usually and especially under a load I feel a rough vibration from the front end. This is especially prominent anytime I turn. You can feel a small chug almost when going down the road at speeds up to 55ish. Once 60-70mph the chug goes away and turns into vibration building and you can feel it underneath you and comes into the wheel. Its not constant but will occur for 10-30 seconds then go away then build back up again. Occurring more and more when accelerating up hills. I have no engine bog, great acceleration and gear shifting. Just the hard vibrations. I have been told to look into the IWE solenoid but wanted to check here first. Lastly, when I had the truck up onto the lift we couldnt spin the fron axle freely when in 2wd. Let me know thoughts please and thanks!

 

How many miles on the spark plugs? If more than 60k, change them. It can miss with no codes. This can cause the "chug" but you have something else going on with the hard vibrations.

 

To my knowledge they haven't been replaced in the 124k miles that is one it. I plan on replacing them but still unsure as to what is causing the vibrations.

 

I would look deeper into the 4x4 not disengaging (going by what you wrote)
you indicated you feel a vibration the wheel, and "Lastly, when I had the truck up onto the lift we couldn't spin the front axle freely when in 2wd"

 

With 124k, the plugs may be causing EVERYTHING. Change them FIRST.

The axle isn't going to spin in 2wd unless the engine is running. Loss of vacuum engages the IWE.

 

Late to the party but will give a few troubleshooting steps that may help.
And if I'm wrong anyone please correct me!

I agree it sounds like iwe / loss of vacuum related based on symptoms.

Engine off, front tires off the ground. You should be able to spin the tires by hand fairly easily, the Cv joints will spin with the tires. IWE's will be engaged.

Engine running front tires off ground, tires should spin without cv's spinning if you're getting proper vacuum to IWE's. Tires will spin even easier than last step.

Engaged in 4wd (might have to pull forward back a bit to engage), everything should of course be locked spinning front tires by hand.

See if your iwe solenoid on the firewall has a plastic hood over the top of it. If it doesn't, change it regardless. If it does, it might be ok but I've had a newer one with the water shield fail too.

Also agree to change you spark plugs regardless, but before you do that and disconnect your battery. Did the shop use a scanner that can check mod$06, or were they just checking for check engine light codes? Mod$06 will tell you which cylinder(s) may be misfiring but haven't hit the threshold for a CEL. This will help after plugs are installed too if you're not looking to do all new COP's at the same time. If you have a smart phone there are apps and obd to wifi adapters that have this functionality that's extremely cost effective.

Hope it's an easy fix!
-Nick