As a result of running a 96 XJ 4.0L 4x4 with a 3 inch lift and 31s, I'm getting a solid 12mpg. I have a roof rack that's ready to be installed, sitting in my garage and I'm sure it will drop my fuel efficency a little more. My friend suggested replacing sensors in the engine since he doesn't think I should be getting that low of mileage either. I popped the hood while my Jeep was running today and noticed that there is a sensor making a ticking noise. I don't really know what it is but it is located near the winshield washer fluid resivour on the firewall. Would replacing this help fix my issue? Let me know!

 

I think its a purge valve for the charcoal canister ( for emissions ), not positive, but almost on any car, youll have that, if its not clicking, its not working! I use to work on toyota and ford, that was normal operation!