Hey guys, I am having an issue with my 19 truck where the past 2 weeks I've been getting this humming/pulsing sound when letting off the gas or braking that goes away when I barely tap the gas. I haven't heard any grinding yet thankfully, but feel my issue could become worse if I don't fix it soon. The issue has also remained after having my tires rotated last week so I'm ruling out a tire issue there. I did some reading and saw stuff about the IWE check valves and solenoids going out so I replaced those thinking that was my issue. Before replacing my solenoid I pulled the hoses off of the hub actuators at the wheels and they did not have suction. After replacing the solenoid I had great suction and drove around for a couple days with no issue, but alas the issue has now returned where both wheels are not getting any vacuum and the port on the solenoid that goes down to them does not have any vacuum when unplugged and in 2 wheel drive...

Am I correct in thinking that I should feel suction on the top port if I unplug that hose while in 2wd and none if switched to 4wd? Also, I did go through a carwash the other day and read that water can get in the solenoid and kill it if I don't have the new model solenoid with the cover, but I have also read that they moved the solenoid to the drivers side to avoid the water issue from the old trucks so is this even a possible issue with my 2019? Do you think water got down in it and that's why it went back out?

I feel like it would easily be a hose issue if I only had vacuum loss on one tire or the other, but instead I have no vacuum coming out of the solenoid itself so it leads me to believe its the solenoid. What about the vacuum reservoir? Could that explain the issue only happening on deceleration or braking?

Thanks for any and all help!
Nate

 

There are some good vids on u tube


I just changed my IWE's

https://www.f150forum.com/f118/iwe-replacement-520545/

Good Luck. Esp if you take it to the dealer.



.

 

@iasus , What trim package do you have, there is ESOF, and there is TOD systems out there.
I don't know what you do or don't know, so forgive me if I sound condescending, I'm not meaning to.
So, what happens on truck when you start it, vacuum will not be introduced downstream of the solenoid until you drive about a mile, then solenoid is energized, allowing vacuum to the IWEs. This sequence happens on EVERY key cycle, regardless of ambient temp.
Without knowing when you checked for vacuum, I can't say solenoid is bad.
Just a WAG, but it sounds as if you may have a bad bearing somewhere, how many miles on the truck.

 

When are you checking for vacuum? Your truck should already have the newer software that keeps the hubs engaged for the first 0.5 miles after being started.
So you may need to drive around the block and then check because the solenoid will not open prior to that.

The concern about water in the solenoid is for the 2005-2008-ish trucks where the new solenoid has a cover. That is long before our generation so you should be OK there.

Next thing you can also check is if each hub will hold vacuum.

This is from the TSB and applies to 2017-2018 so I think 2019 should already have it.
Note: The new TCCM calibration changes IWE operation at start up. When ambient temperature is above 0°C (32°F) the IWEs stay engaged regardless of a 4WD mode selection for approximately 0.8 km (0.5 miles). IWE engagement only occurs once per key cycle and is not reset when shifting between PARK and DRIVE. The TCCM uses this strategy to delay vacuum use until vacuum-intensive engine startup has completed and sufficient vacuum is available to fully disengage

 

Thank you everyone. I was not aware of the half mile and was just starting the engine from park. I will definitely give it a go this afternoon and report back. I've got a suspicious feeling it is the hub itself then because the time I replaced the solenoid I drove it around to see if the noise went away before pulling the plugs after.

Would the hubs not make noise on acceleration as well if they are not holding vacuum though? I guess I ruled out the hubs because it only happens when I decelerate or brake thinking it was some sort of loss of vacuum at that point.

@johnday in BFE Thank you for your comments and I have the 4x4 ESOF

 

Hubs are not a part of the vacuum system, bearings only. The IWE is the part that uses vacuum to disengage, no vacuum, engaged. It doesn't sound like you're grinding anything. The IWEs, if you had a vacuum leak, would normally grind under acceleration, and it doesn't sound like that's what you have.
This is the sound of a grinding IWE.

 

I just drove around the block and checked. Vacuum is 100% there on both sides and strong. What do you think could be causing the humming/pulsing sound coming from my front left end? IWE actuator? It was making the sound before and after having my tires rotated. It also doesn't seem to matter if I'm turning left or right so I'm not thinking a wheel bearing. It makes a WOM WOOM WOOOM sound. Do you think it could be the front differential?

Thanks for any help

 

Glad you were able to confirm vacuum is strong. Sorry I don't have any good suggestions about the woom woom woom sound.

 

Don't think it's the front diff since you have the ESOF system, halfshafts and diff shouldn't be turning at all in 2H.
I'm thinking bearing, only way to truly find out is to take the hub out and look. Trying to shake tire/wheel up, down, and side to side is not a reliable way to see, unless the bearing is completely gone.
You could jack up that corner, leave it in 2H with vacuum formed and see if any roughness is there. Suggest you use a handheld vacuum pump, engine running could drown out any noises you might hear.

 

Thanks, I will jack it up and see if there's any play since it will be next weekend before I'm able to actually do any work on it. Does the fact that there's humming/vibration instead of a grinding noise rule out the IWE hub actuator?