I've been looking for some information regarding modification of the intake resonator/plenum/black box and this post seems to address it. Sorry if its super old.Just a update, as you have already read I did indeed install the K&N CAI Kit for my 2006 XK 3.7L I took notes on this project, before the install I was getting about 13.4 mpg in town (according to the on board computer display). I installed the kit and disconnected the postive side of the battery and turned the ignition key to start and held it their for about 60 secs and release it and left it that way (battery disconnected) for about an hour.
I went from 13.4 mpg in town to 14.6 in town. Now I got to thinking I should be getting better gas mileage than this. So I went back to the CAI filter (cold air intake) and traced the route of the airflow. From the filter up to the black box mounted on the throttle body (sorry dont know what its really called) all was well, the airflow path was nice and smooth, I then decided to inspect the black box!
I took off the black Box and looked inside of it, I got my flashlight (It was cold and dark and scary in thier) and I noticed slots (on both sides of the airflow path) inside of the box along the airway path! I took a small metal rod and pushed it though the slots to see if it went all the way though, and of course the rod went all the way though slots. Bingo I found a airway problem!!! Seems air was being suck in and going though those damn slots maybe causing airflow problems!!
I keep looking at the inside of that damn box for about 30mins deciding what would be the best way to block the damn slots, then it hit me, A/C Heating sealing tape!!! I remebered see a Mike Homles on homes program and they were using the tape on the homes a/c heating duct work,its silver on one side and super sticky on the other side and its SUPER thin!!! I got the same tape from a friend of mine who is a a/c heating tech and I used that on some of my duct work. Its super sticky and its made for the cold/hot air in the duct work.
I got the box and removed the airflow sensor (more room for my hand) and cut two strips of tape and made sure they over lapped at each end of the box openings. So far so good, I removed the paper off the sticky side and began to apply the tape over the open slots, Working like champ!!! I then pushed the over lapped ends of the tape down the other side of the box openings (this way if the tape came loose it wouldn't be sucked down the damn thottle body opening).
It finally warmed up here and I got on the interstate to warm up the engine and them came home and put the JC into my garage and let it set for about 30mins or so. I opened up the hood and felt the box black, BOY was it nice and hot!!! I let the JC set for a whie longer. Now the moment of truth was the tape still sticking or did it come loose? I took off the box and looked inside, It was still their covering the slots!!!! I jumped up and down with delight (until the boss heard the nosie I was making and asked what I was doing, of course I told her I hurt my hand and she then left!!). After about two weeks now the tape is holdin up like a champ!!!! My mileage went from 13.4 to 16mpg!!! and that in town driving and my heavy foot!! Remember if you do this don't use the GRAY DUCT TAPE!!!!
The black box takes about 3mins of yer time to take off and to check the tape, To date its working like a champ!!! Hope this mod helps out someone. If you find a better way to cover the slots please let me know!!
Has anyone else done this simple mod?
Looks like he is talking about Butyl foil tape
I already removed the cover over the intake behind the grille.
I plan to remove the cup on the bottom of the downpipe from the airfilter box and leave that hole open.
I don't plan on any deep water crossings with this vehicle of course.