Truck Symptoms: (2017 f150 lariat 4auto transmision, 6spd, 2.7, 1.5-2" level)
-Mild Vibration felt by feet through floor/gas pedal, also can hear it a bit.
-Maybe both sides, Maybe L>R, Seems like from the front Left.

• Happens after about 20min of driving (once warmed up), then worsens for a bit then plateau.
  Happens mostly with gentle/subtle Right turns
  Happens mostly on Gentle Acceleration
  Is still Intermittent.
  Truck has 1.5-2" front level, otherwise stock.
  

Other Findings

• Doesnt change with 4x4/2wd (? Rules out Transfer case?).
• Changing Rims/Tires to Summers didnt change anything.
• Getting a Transmission Fluid/Filter change didnt change anything.
• Pulling the IWE vacuum line stopped the low speed grinding noises (engage IWE full time), But once those low speed grinding noises were gone I was still left with the higher speed vibration feeling.
• IWE hubs both loose vacuum slowly (pressure tested to 25, slowly lost pressure)
  • So IWE actuators likely have a diaphragm issue,
    BUT since we pulled the vacuum lines does that loosing vacuum matter?
    • Did it do enough damage to the IWE splines to not let it engage and slip sometimes when light acceleration/turning but still in 2wd? Causing the vibration?
      
• IWE hoses dont loose vacuum (block IWE ends, vacuum after solenoid doesnt drop).
  
• When jacked up the wheels turn the front CV axles
  • Showing that the IWE are engaged? (again, higher speeds and once warmed up could they be slipping during Right hand turns?).
    

Some things I Feel I should check/rule out?

1. Check Front Diff fluid – levels/quality? (Was changed @ Ford ~20,000km ago)
   • could the partially engaged IWE damage this?
2. Front CV axle?
3. Front wheel bearing?

Been to ford.
-They couldnt reproduce but pulled the vacuum line (per TSB).
-They said next steps were to take out the leveling kit and replace IWE's (1200-2000$), Didnt mention CV or Wheel bearing or front diff.

Unsure what to do next, looking for advice.

 

Did you check to see if the tires are chopped? Pretty common with A/T tires and leveling kit, I'm assuming you're running larger wheels or oversized tires, I'm surprised they didn't recommend a road force balance

 

Stock diameter tires.
was running 17” winters.
just swapped to stock 20” summer A/S E-rated.
didn’t make a difference.

 

had similar issue wound up being a wheel bearing when jacked up there was no play when i tried to move wheel side to side but obvious play when i tried to move top to bottom

 

Jacked up truck.

-with vacuum added to iwe directly there is a slow leak over several minutes.

-with vacuum added CV doesn’t spin but there IS a slight grinding noise as wheel rotates though part of the rotation. Same every rotation.
Left more than right.

-no instability in tire wheel in any direction.


-when iwe engaged (no vacuum) CV spin.
-when iwe engaged alternating wheel counter/clockwise there is some clunking as i change direction down by the transfer case.
UNSURE if this is normal.

 

See attached

 

And this

 

Did you ever figure it out? Working through this same exact issue currently.
For vaccuum on IWE, are you certain that you aren't losing pressure through the vacuum tube (of the tool) rather than the hub itself? My vacuum tube is too big to hold pressure so when I tested it leaks air unless I hold it tight or ziptie it. Gonna try to find a better way to test it with a more secure fitting.

FYI I did left wheel hub and in the process of torquing the axle nute, snapped the end of the drive shaft/spindle off so ended up replacing the axle and axle seal as well. No dice on any of it fixing the vibration/hum.

 

kinda.

I did both IWE, then did the tsb to engage them all the time. Guessing that the iwe were broken and that’s why the tsb didn’t worth the first time.

I had to use zap strap to test vacuum originally.
eventually got some much stretchier thicker tubing (exercise tubing actually) that worked great for the different size nipples for testing vacuum.

This combo got rid of 90% of the vibrations.

still can feel it a tiny bit but might just be how it feel with iwe engaged.


happy because the next thing to look at would have been front diff or transfer case or something bigger.

 

Had similar issue about 5yrs ago, and it turned out to be a combination of tire cupping and differential carrier bearing. It took the dealer a while to solve it, with chassis ears and stethoscope. It was driving me nuts so I know the feeling.
When you add a level kit, did you also happen to do the UCA?