Got bored last weekend and, with the wife's blessing (it is her vehicle), I made an intake with the left over parts from making an intake for my Jeep (and other projects). I didn't have enough pieces to get the filter into the fender, so I went with a short ram style of intake. I really don't know how much this would cost because this was all spare parts, but i believe this is right around $75.
This is something I like do to all my vehicles. I know there isn't much, if any performance gain without a supporting tune, but i like the sound of the engine you get with this kind of setup. Plus there is also that little bit of me that likes to say "i made that, it is shiny, and it works."
Almost all the parts came from the *cough* performance *cough* aisle in Autozone.
Here is what it looks like:
3" to 2.5" Spectre PVC reducer
3" Spectre PVC Coupler
45 degree 3" Spectre elbow (a 30 degree one works just fine too)
3" MAF adapter from Spectre
Cone filter of some kind you can attach to the MAF Adapter (I used the Spectre one)
3/8" Threaded Hose Barb
JB Weld Gasket maker/Sealant (the grey stuff)
1.5 feet of 1/2" I.D. (inside diameter) vacuum hose of some kind
1.5" wide Aluminum Bar *Note: i found this at Lowes, i had to buy 3 feet for another project, you only really need about 6 inches, you can use plastic if you want. This is what i had on hand.
1. Disconnect the battery (optional, but it is habit for me), and remove the entire stock intake system, and the vacuum line. pull out the MAF sensor.
2. Attach the narrow end of the Reducer to the throttle body. You are going to have to stretch this, and it really helps things if you warm up the Reducer. I used a heat gun on
"low" but you can let it sit in hot water for a bit too. Clamp it down.
3. Take the Elbow and on either side of the bend (your choice), drill a hole just large enough for you to thread the hose barb in. Screw that down a bit then put a bead of the gasket maker around the base of the barb to seal things off. Set aside to dry.
4. Using the MAF adapter, select the pad that the MAF Sensor fits snugly into. It is NOT the one listed for "Mazda." i think it was the GM one, the one with the least amount of black plastic and the only one the MAF actually fit into. You will need to orient the MAF sensor so the hole is inline with the tube. Air needs to flow directly into this. Secure it with a screw so it doesn't move. None of the provided screw holes line up so you will have to make your own. You will have to drill a tiny pilot hole. Don't go too crazy, you just need to keep the MAF in one spot and keep it from moving. I only used one screw and it is quite secure.
5. Now this is the most important part. I used the stock airbox as a guide and just attached everything and went for a test drive. Got a p0171 (system too lean) code after a run down the highway while sitting at a light. Checked the fuel trim with my scan tool and it showed the short term fuel trim was running positive (2-4%) at idle (should be at or right around 0).
To over simplify things: means the O2 sensor is seeing more air than what is being reported by the MAF, so the ECU responds by and adding more fuel, but there is still too much air leading to a lean condition and thus, the check engine light. My experience with MAF's is that they work best with little to no turbulence, the airflow does not need to be laminar (unlike with older MAF's), but you want it to be as turbulence free as possible. My guess was since the MAF was close to the filter, there is enough turbulence to confuse the MAF. So I added two internal fins, made from the aluminum bar, on either side of the MAF sensor. A screen of some kind might also work, but I was using what I had on hand, and this setup has worked in the past for me.
I cut them to about 2.75" in length. The fins sit about an inch apart with the MAF in the middle. I used tape to hold them in place and built up the gasket maker/sealant where the fins touched the tube. You want to make the fins and the MAF as parallel as possible:
Let it fully dry and very carefully peel of the tape.
This is what it looks like after the tape is off (you can also see the screw i used to hold the MAF in place)
6. Attach the MAF section to the cone filter. Make sure the MAF opening is pointing towards the cone filter (don't be an idiot like me, thank goodness i double check things)
7. Attach the Elbow to the MAF/Cone filter using the 3"coupler. Make sure the Hose barb is on top.
8. Attach everything to the throttle body.
9. Attach the Vacuum line, and trim it to a proper length, then plug in the MAF sensor.
10. Reconnect the battery
11. Start the car and let things idle for about 5-10 minutes to let the ECU figure things out since it has been completely reset.
My wife has put about 300 miles on Mazda with this setup, in all sorts of driving conditions and no codes have popped up. She says it feels like the CX-3 has more "jump" to it when you step on the throttle, and she really likes the way the engine sounds at WOT.