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Air Box Mod

10K views 7 replies 3 participants last post by  Mongo 
#1 · (Edited)
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!!
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.

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.
 
#2 ·
No one seems interested in this I guess.

After some looking around it appears that the Jeep Liberty has a straight through intake elbow that does not have the resonator/silencer on it like the XK 3.7L intake has.

Looking into messing around with that.
 
#3 ·
...I plan to remove the cup on the bottom of the downpipe from the airfilter box and leave that hole open...
Am I missing something? If you do this, you'll have an open hole in the inductions system between the air filter and engine, thus sucking in unfiltered air? How would that be good? I must be missing what your saying.

Why NOT buy a CAI?

The resonators in the induction system shouldn't hurt performance (perhaps that conventional wisdom is wrong), but the best way to keep a vehicle reliable and dependable is too keep it stock and well maintained. I think that is why you see so little interest in fiddling with the induction system. People either want it stock to be most reliable or they get a CAI.

I have taken the air box on the TB/engine off several times and looked it over, but admittedly NOT extremely close. I've never noticed any slots or openings like the original poster was talking about in his post. I will look closer next time. If they are their I can only imagine they are flaws in production or some sort of safety feature to prevent sucking up water from a flooded air filter box?
 
#4 · (Edited)
You are confused, my post wasn't very clear.

That airbox/resonator has secondary passages for air to be redirected to which quiet down the intake noise. Blocking off these passages may improve the airflow.

No hole would be opened to open air between filter and throttle body, there is a water drain at the bottom of the air filter box (before the filter) that may be uncapped and allow for increased airflow in that area as well.

Why not buy a CAI? I live in CA, and 50 state legal CAI's are ridiculously expensive, and I like a similar to factory look, I am looking into trying the Liberty Intake elbow (instead of the black box/intake resonator) and trying to find a way to replace the flexible hose with something that would flow better (maybe black PVC and black silicone couplers?)

Thanks for the response! :)

I am not much of a fan of the looks of most "CAI" kits, though the airaid JR would be nice, but alas its 5.7L only.
 
#5 ·
Not worth the risk of sucking tape into your engine.
Find something to replace the intake resonator with.
Ive been meaning to find a Grand Cherokee SRT8 intake to try out on my 5.7L


Just keep in mind most likely there is a sensor in our intake that you will have to transfer to a new tube.
 
#6 ·
Not worth the risk of sucking tape into your engine.
Find something to replace the intake resonator with.

Ive been meaning to find a Grand Cherokee SRT8 intake to try out on my 5.7L


Just keep in mind most likely there is a sensor in our intake that you will have to transfer to a new tube.
That is the conclusion that I have come to. I am on the lookout for a 3.7L Liberty intake elbow, which has no resonator. It takes care of both of these issues.

I wish I could go that route. There is usually one of those for sale on the srt8 forums for cheap
 
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