I have a K&N on my '07 5.4L. I noticed a decrease in MPG's last few days so I just popped the hood and noticed the filter fell off. Weather's been hot & cold back and forth lately, causing the clamp to wiggle free. What I'm wondering is how badly effected the motor could be from the lack of filtration? And of course I'm currently going over and tightening everything..

 

Well the way I see it is that it's not good but as long as your engine seems to running fine then you should be okay. There's no going back or fixing it really so just make sure your filters stays on and don't worry about it.

 

The weather did it ?? lol clean your MAF and throttle body and make sure you tighten it up this time...