I have a 2015 ecoboost 4wd. I recently replaced both IWE's due to an intermittent grinding noise that went away in 4x4. It fixed it, but the issue I have now is the new IWE's (TRQ from 1A auto) make a distinctive popping noise when I turn the truck off and the vacuum vents. It may be normal, but the factory parts never did it. Everything works, it just pops when the vacuum vents. I made sure the gears were meshed and everything is installed correctly. 4x4 works perfectly and I have no issues besides this. If anyone has experienced this I'd love to hear about it.