Focus Fanatics Forum banner

Stealth CAI--What to expect and what NOT to do.

50K views 86 replies 46 participants last post by  07Zx3Focus 
#1 · (Edited)
There is at least one good Stealth CAI guide out there right now. You can find it HERE. I used it as a basis for doing my own stealth mod. Other than that, I can't find a proper guide or even guidance from others here regarding the pro's and cons of this method of introducing a Stealth CAI to your Focus. I'm not providing pictures because while I was working on the car, a freak storm occurred and brought two tornadoes with it. In other words, I was doing a lot of ducking and covering thanks to the healthy wind, rain and hail. The second tornado got so close that things were being sucked out of the yard and the covered garage area I was working in. Sounded like a freight train going by! I digress.

The tutorial does a good job of using pictures to show you what to expect. In all fairness though, the tutorial does a poor job of describing what to do when you're prepping the car for the mod. I believe the author's intent was to focus (no pun intended) on the actual mod itself rather than what comes before it. This is my attempt to help you out in some small way so that you'll not only know what to expect, but you'll be better prepared than I was and it could save you some precious time if you're trying to get it done and get on with life.

I know that not everyone has a nice hydraulic floor jack, but I'm blessed with a father-in-law who has just about everything you'd possibly need to build or tear apart a car. In the worst case scenario, you could use the jack from your trunk to lift the front driver side wheel high enough to remove it. Take caution when doing this as those jacks aren't especially steady. Make sure you're on solid, flat ground. I recommend a driveway or parking lot. Also make sure (for safety's sake) that you put a block under there to assist in keeping the car stable. The last precaution is using your E-Brake. This helps keep the car stationary.

Once you have the car jacked up and the wheel removed, the fun part begins. The tutorial states that you should not only remove the wheel well but also the splash guard on the front of the car. Removing the splash guard is not only a waste of time, but a PITA. The wheel well removal is fairly simple if you know what you're going to be doing. There are about 5 Phillips screws and one small bolt (sorry, can't remember the size right now) that you'll have to remove in order to see and remove the factory air filter. Keep in mind that the Phillips screws are secured in a fashion that's similar to drywall mounting screws. There is a quartered piece of plastic that surrounds the screw. Once you loosen it enough, you can pop it out of the body with no problem at all. The key is to keep loosening a few turns more when you think you've done enough. The cover is sitting in two small slots to help secure it in place. One of them is at the top of the wheel well and the other is near the driver side door. They easily pop out and you can push it around to remove it out of the two slots it's sitting on.

Once the wheel well is free and clear, you can remove the two bolts that attach the factory air filter box to the frame. Once those two bolts are out, you can easily follow the other directions and have a great deal of success.

NOW: Here's what else I learned the hard way. The author states that a filter with a 3" ID will work but it's a tight fit. I'm here to tell you now that even attempting this is a waste of 25 dollars in a filter. I kept at it for an hour and still couldn't get it on there properly. Even my 6 year old started repeating my mantra of "Almost...Almost!" every few seconds. After he finally said: "Daddy, that filter is PWN'ing you!" I got the hint and went back to the store. My solution was an APC filter from Advance Auto to replace it. The filter had three ID choices in 3, 3 1/2 & 4 inches. AGAIN! Don't bother trying to use the 3" adapter. Simply use the 3 1/2 adapter. At first it'll remind you of the old adage: "Like Parking Your Bicycle In An Airplane Hanger". Take heart. The filter is equipped with a hose clamp that will not only correct this issue, but do a darned fine job of it in the process. Once that's done, follow the rest of the instructions to put it all back together. Keep in mind that the two bolts you removed to take out the stock air box will no longer be used.

Another Note:

When you first crank up the car, be prepared for a bit of sputtering and maybe a mild backfire when you rev the engine a bit. Your ECU is going to have to adjust to the change you just made. Let it idle about 5 minutes and you're good to go. The throttle response is much improved and you'll feel the extra torque. This is by far the cheapest mod you can perform on your Focus and actually feel the difference it makes.

Enjoy and feel free to PM me with any questions you may have!
 
See less See more
#3 ·
a 3 inch filter is a pain in the ass to put in. that's why i'm using a 3.5" coupler over a 3" coupler with my design. check it out!



 
#5 ·
great write up... what i dont understand is that you say the 3 inch filter wont fit... the 3 inch filter i have fits great on the end of the MAF tube.... took a little bit of a strech but its on and has been goin good for a while now. maybe i got luck... but none the less good write up!
 
#10 ·
It depends on the brand of filter I'm thinking. Some filters have a more flexible rubber compound whereas others are stiffer. Even using a screw driver to help things along (yes, I tried almost every lube known to man...I'll leave that to your imagination) and it was still a bust.

The author notes that you can get a K&N that fits on there perfectly with a 3.25 ID but that's only if you're in the market for a 60 dollar filter. Since I had to go through 2 filters to get it to work, I should have just bought the danged K&N the first time.
 
#13 ·
Sort of helps if you pay attention to the article before you run out and spend a bunch of money!

As I stated I used a Spectra filter with a 3”, 3 1/2” and 4” opening. Many people have used this article to build an inexpensive CAI, I am still using it to this day with no adverse affects.

I’m glad I could help direct people towards and effective and inexpensive CAI.

Enjoy
BlazingCopper_ZX3
 
  • Like
Reactions: ww1313
#11 ·
Great job and good thinking bro!!

I'm a tad ashamed and surprised that nobody else thought of it. Now you just have to get rid of the silencer box, and you'll be home free to a homemade CAI [thumb]
 
#12 ·
i'll probably be selling my Stealth CAI v.2 piping from my car. I have Cool-Flo now, so I won't be able to use it.
 
#14 · (Edited)
Your article helped me tremendously. I was just building on it a bit to help those who aren't overly familiar with some of the mundane portions of "getting started".

Thanks again!

PS. I also went with the Spectra brand the first time. I should have done some more searching but at the moment, my local auto parts store only had the 3" filter in stock. Lesson learned!
 
#19 ·
If you guys have ever noticed, the stock intake draws air from the front lower grill. There is a duct there, so it would be smart to use Y type tubing that leads there to one of those filters where the front of it is open for tubing and the rest looks like a normal filter(pepboys has these) and putting one of those mesh screens on it that prevents hydrolocking. So you have a filter drawing really cold air and then the stealth filter thats boxed in drawing in secondary air so its like having two places where you get cold air from making alot more air flow. What do you guys think?

Also with any filter install, make sure to unhook the battery negative terminal to reset your ECU so that the car goes into emissions learning mode and the sputtering doesn't happen.
 
#20 ·
you could unhook the battery or just let the car idle for like 10 minutes. it'll relrearn.
 
#21 ·
FYI guys, i'm going to be selling my version of my Stealth CAI. it's for the guys who think the filter may sit a little too low. i'm selling the piping i added to tuck my filter up in the fender wall. PM me if you are interested.

 
#24 ·
It's actually not that hard of an install. I'll give you pointers if you decide to buy the piping with the filter included. I responded to your pm.
 
#26 ·
I was able to get a 3"id coupler then a 3" 90* pipe then the 3" filter on with a lot of stretching and grease. its worked for me. Here is my tutorial edit:
http://www.focusfanatics.com/forum/showthread.php?t=218642

But im not gunna lie, it was a bitch to get on. i ended up puting the couple around a metal bottle, then putting various screwdrivers and Allen wrenches in between the coupler and the metal bottle to stretch it then grease. i almost gave up it worked out!
 
#27 ·
i recently tried this out and somewhat had success. It works awesome and you can notice the difference but whenever i hook up my mass air flow sensor the car starts to spudder at around 3000 rpm. its so bad that all through 5th gear i can barely go past 45. any suggestions? i've tried disconnecting the battery to reset the computer but no luck. it works just fine without the MAF but the check engine light turns on. any help would be greatly appreciated.
 
#28 ·
A little heat and those couplers really helps out the stretching process.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top