Hey everyone, this is my first post here. Hopefully I can figure out what is causing this weird hum / vibration on my truck. I have read several posts on this with no solutions, however not covered quite what I have going on.

I have a 2007, FX4 SCREW. 5.4L, limited slip, AEF CAI, 3:73 years, Edge CTS tuner, 6" lift, 35" mud tires.

I have owned the truck for about 4 years. I have noticed it happening for years, but it does not appear to be getting worse. This last weekend I was driving to Wyoming, and it was a 7 hour drive. During this time I had time to make some observations that might help pinpoint this.

I thought it might have been exhaust drone or something because I had a Magnaflow straight through muffler, I figured it might be just a hollow exhaust vibration. However that muffler got damaged, and I had the muffler shop install a new OEM muffler. So on my way home, I noticed that the sound is still there. Here is what happens.
My edge CTS tuner shows me what gear I am in. I noticed that there is a "padlock" next to the gear number, I assume this is an overdrive or something. Anyways, the only time the truck makes the noise is when I accelerate within the pedal "dead spots". Best way I can explain this is when my tuner shows (4th gear with padlock) and I am cruising that 70 MPH. I come to a slight hill, and there is that small "dead spot" in the pedal (usually 1/2-3/4" travel) where 4th overdrive is no longer able to accelerate or maintain the truck speed, but before it shifts out of overdrive. when I press the pedal anywhere within that 1/2-3/4" zone, I get a hum / vibration which sounds like it is coming from behind the firewall. Unless the "padlock" is shown on the gear screen, it does not make the sound when doing slight accelerations.

Here is where it gets weird. If I tune the truck, using one of the stock edge tunes, the noise is a little louder, and it happens a lot more often.

My tuner came with these 3 tunes. (stock, level 1 (transmission only), Level 2 (towing), and level 3 (91 octane).

If I have it tuned to stock, the noise is there, but pretty quiet.
If I have the truck tuned to level 1 (which I do 80% of the time) the noise is as I described above.
If I have it tuned to level 2, the noise is a bit louder, and is heard in a lot more pedal positions
if I have it tuned to level 3, the noise is almost constant regardless of gear with or without padlock.

So since i have had the tuner, I have only tuned it to level 3 for about 2 days and the noise was too irritating, so I usually never go higher than level 1.

I can hear the mud tires, and it is definitely not the tires making the noise. Does anyone know why this noise would change with the different tunes from the Edge tuner? I am hoping that the noise mainly there when it shows a gear padlock, and the different tunes affecting the sound may help pinpoint what could be causing the noise.

Thanks everyone!

 

Pretty sure the ‘padlock’ symbol would indicate when torque convert is locked.

? You mentioned ‘mud tires’, assuming they are not stock dimensions, did you use the edge to reprogram truck/tuner to factor the new tires?

 

could be your cold air intake .. mine sounds weird at times.

 

Check the gasket around the air filter tray, mine deteriorated and made a hum like you describe and it was really annoying. I replaced the gasket and it went away.

edit, nevermind, just saw you have an aftermarket intake.

 

Yes, they are XD 20" chrome wheels with 35" nighthawk MT tires. I bought the tuner just to reprogram the speedo. The edge tuner shows the speed correctly, however the dash speedo is accurate until 50 mph, then it is 3 mph higher than the tuner shows.

I guess it could be the air intake making noise, it just sounds like a deep hum like it is engine or transmission related. So the noise only happens when the torque converter is locked.. The strangest thing...

 

I'd investigate the iwe problem where they partially engage and grind under acceleration due to low vacuum or a vacuum leak. I would think that in od with the torque converter locked if you start going up a hill or loading the engine the conditions would be right.

 

What is the IWE?