Here we are again. As a follow up to my last thread post; i’ve Now double checked all vacuum including plugging and testing the reservoir. I brought my tools with me on the last drive and when i started hearing the noise, i got out and hooked up a meter to my solenoid.

Im aware of the .5 mile/5min buffer with the tccm updates. 2019 already has the update anyway.

At idle and while driving, i dont get even 1 full volt. Thought maybe my leads were wrong or i didnt get the probes set right. Checked it all, swapped my leads for ****s and giggles and it’s obviously not making any difference.

I know the ground cuts out when going to 4x4 but i should receive voltage regardless. It gets power because the solenoid works. I’m wondering if it’s Not enough juice or whatever. I don’t know anymore.

But i’m not replacing anymore parts until i figure this out. Anyone have wiring diagrams or any info? It should be 9+ volts if i’m not mistaken.

No i wont do the TSB cap off, dont mention it, yes ive done both hubs and actuators, blah blah blah. my whole IWE system is new except the driver CV axle.

2019 XLT 3.5 eco.

 

In 2wd, voltage at solenoid connector is around 5 volts. Check using a MM, at supply to the solenoid, and connect to other probe at connector.. Then put in 4wd, and check power across the connections at connector, IIRC should be about .5 volt or so. Ground is switched at the TCCM.
I think I read your post correctly.
Yes, power supply is constant.

 

So when the ground signal was applied to one side of the solenoid coil and you say the solenoid works, did you pull the hose off the output of the solenoid to see if you have suction there? Just because a solenoid is energized does not mean it has suction going in and or passing the suction going out. A solenoid uses a coil of wire to create a magnetic field to control a plunger valve to pass or block air flow. Solenoids activate with electrical current flow. So with a good ground signal applied to one end of the solenoid coil a piece of wire is all a coil is, if there is no current flow both ends of the solenoid coil, just a piece of coiled wire, you will measure no voltage across it. The hot side of the solenoid coil is connected to a constant source voltage, when the ground is removed from the actuation signal, the hot side will float up to what ever voltage the source is because there is no current flow to drag the source down. So it will read what ever voltage the source is connected to. Once the solenoid control lead is shorted to ground by the control module, if the wiring to the source or a connection to the source has gone resistive it will be dragged down and the voltage will be dropped by the resistance of the source wire and no voltage drop is across the solenoid coil and no current is flowing. At idle the ecoboost produces it's max vacuum, your vacuum gauge going into the check valve should be 20 inches, out of the check valve should be 20 inches, into the vacuum reservoir 20", out of the reservoir 20" into the solenoid 20" out of the solenoid 20" at the vacuum line to each IWE 20". Now if all of that is good, check the IWE vent lines. A vacuum IWE diaphragm can not actuate if it's vent line is plugged to outside air. If all that is OK mechanically the diaphragm can tear loose from the actual IWE gear, alo allowing it to grind too much for too long can take off the engagement splines off the drive hubs causing slippage. Another common issue is the monkey who installed new factory greased IWEs thought that's not enough grease and added more grease because more grease has to be more better. This usually shows up in cold weather when more better grease gets thick and won't like the IWE ring gear slide freely.

 

I mean the solenoid actually has vacuum, i took the hose off and can feel it.

 

I would suggest a vacuum gauge set from harbor freight tools since you can not feel the level of suck with your finger. Ok you have some suck. Harbor Freight sell a brake bleed vacuum set that has a vacuum gauge multiple fittings and some hose. Coming off the output of the solenoid you can install a short piece of hose, a tee fitting from the kit, one end of the t fitting goes to the vacuum gauge, the other end of the tee fitting goes to the IWE supply hose. You now can measure your actual amount of suck, again you should have 20 inches' The IWEs will actuate around 10 inches, but they will grind as they transition with that low a vacuum. You can also connect the vacuum hand pump direct to the line going to the IWEs and pump it to 20 inches, if the vacuum does not hold for a few minutes before leaking down, you have a leak, with a bad IWE, or a crack in a line. You can also measure the vacuum at the IWE connection it's self. The IWE might be good, but the hose pushing on to the IWE has swollen and is loose and leaky. Some snip off 1" of the expanded loose IWE hose at the actual IWE, some put a tiny cable tie around the hose and cinch it up to seal. Also a cracking hose going to one IWE or the other might seal fine, but when steering right or left the hose flexes opening the crack in the hose.

 

No more than 18 inches. Ive done every other test possible. My only guess now is if i reallyyyyy need the last two inches, i need to replace the solenoid. Or i replace my driver axle to rid the sound. I’ve replaced EVERY other component on this truck’s IWE.

 

If the vacuum holds at 18 with no leakdown that system should work fine. you can put a tee connection on the output of the solenoid and sneak a hose out of the hood, connect it to the above gauge tape the gauge to the windshield and drive around and see how the vacuum levels are as you drive and when the noise happens. Turbo engines have poor vacuum levels the harder you accelerate and best vacuum levels at idle. That is the purpose of the check valve and the vacuum tank, to hold/maintain the best vacuum levels in the reservoir and stop leakback from the reservoir when engine vacuum is lowest. My original damage was due to leakback by failed checkvalve complicated by my poor hearing until it was too late and the grinding had eaten the IWE ring and the splines on the hubs so both had to be replaced. I put two of the new style blue/white Ford check valves in series on the supply line to help prevent the issue in case of future failure of one checkvalve.

 

Could you show me your double check valves? how you have them set up?

 

inline with first OEM check valve, snip hose in half add second inline check valve.

 

Vacuum on Natural Aspirated engines work the same way, just that with turbos/blowers, it decays much more rapidly.