Strange sound in 2x4 mode, after weeks in 4 AUTO

[Ohio JEA]

I have 2012, heavy snow here in OH this winter, so I used the 4 Auto quite a bit. Anyway, now that it's back in 2H - I notice a strange intermittent rattle noise that lasts about 3-4 seconds then goes away. Sounds like it comes from the front left side. Usually under light acceleration, 1400-1600 RPM only. You don't hear it when under load or during quick acceleration. I have taken to mechanic 2 x and they cannot make the sound appear when they test drive. Frustrating. Ideas?

 

[mr_dave]

Check out this video, it could be a few things. Most simple items are a $10 vacuum check valve or $20 vacuum solenoid.

Ford F150 4X4 Diagnosis No Tools Required

You can get the new solenoid version Here-http://www.amazon.com/gp/product/B004SR7JVO/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B004SR7JVO&...

www.youtube.com

 

[maxxplatinum9137]

IWEs are trying to engage still. Probably have vacuum leak somewhere. That’s why you shouldnt ride around in 4A

 

[tommyddsr]

IWEs are trying to engage still. Probably have vacuum leak somewhere. That’s why you shouldnt ride around in 4A

Are you implying 4A causes vacuum leaks in the IWE system?