MS6 - AEM CAI Issue and fix w/ modification how to
 

During my previous vacation from MSF I ran into a problem with my car throwing P2187 lean and idle code. I checked for air leaks and fuel pressure and come to find out it was due to my AEM CAI that has been on the car for over 8 months, it just started to throw the code all of the sudden. I put the stock intake back on it and it was fine.

So I started looking at my AEM and noticed that it didn't have a air straighter, so I bought a AEM Air-Straightener for Mazdaspeed3 2007-2010. Well when I went to install it, it didn't fit and flopped around in the intake pipe. Come to find out the piping for the MS3 is 2.75" and the piping for the MS6 is 3" in diameter, why they use different sizes beats me.

So during my attempt to install the AEM Air-Straightener I noticed that the AEM had a metal sleeve in it right where the MAF Sensor goes. Apparently AEM installs the sleeve in the intake to help keep the MAF Cal close to stock so it doesn't throw any lean or rich codes or go zoom zoom boom.

Here is were I see a issue....actually two. The first issue it there is a sleeve in the intake that reduces the intake pipe diameter from 3.0" to 2.75" so its not a true 3' intake (pipe id is 2.9"). The second issue I see is that the sleeve is right where the MAF Sensor is, so when the air in the intake needs to be moving nice and straight through the intake it necks down from 3" to 2.75" then back to 3" causing unwanted turbulence in the intake right at the MAF Sensor and screwing with the MAF Cal.

So I decided to fix it....the way it should be.

1. Remove AEM CAI from the car and remove the MAF Sensor.

2. Take a look inside the intake where the MAF goes and locate the sleeve.

3. Once you have located the sleeve take a fine toothed hack saw blade and cut a groove through the sleeve right were the hole for the maf goes, but be careful not to cut into the intake pipe.

4. After you have cut a grove through the sleeve take a small flat blade screw driver and pry up the edge of the sleeve right were you made your cut - !!!! be careful not to bend the intake pipe!!! The intake is made from some really thin aluminum and bends really easy.

5. once you have pried up the edge take a pair of pliers and grab the edge of the sleeve and pull the sleeve out while twisting the intake back and forth

6. With the sleeve out take some 300-400 grit sand paper and lightly sand the intake were the sleeve was to make it nice and smooth.

6.5 now Install honeycomb style MAF Air Straightener and place it about 1" past the hole for the MAF sensor, recommend but not necessary. MAF straightener was purchased from JBR - 96mm MAF Straigtener

7. reinstall intake and maf sensor

Now your AEM is a true 3" intake...but you are not finished

The size of the intake has now gotten bigger, so a MAF cal is a must.

Before it was 2.69" in diam and now it is 2.85"
so take 2.85/2.69= 1.06 then go into AP and multiple your entire MAF curve by 1.06. Once you do that you will have a good base line for your MAF curve but it will need to be fine tuned.

Since I did this a while ago I don't have any pics of the process but here is a few pics of the sleeve so you can at least get the idea.

http://www.o-m-g-w-t-f.com/aem1.jpg
http://www.o-m-g-w-t-f.com/aem2.jpg
http://www.o-m-g-w-t-f.com/aem3.jpg

The AEM CAI maxes out at about 400 g/s so it's not bad out of the box and the biggest "oem style" MAF out there.

Have you tried running this without the air straightener? It's probably not needed.

Actually I just installed the Air Straightener yesterday, been dealing fuel trims issues at and just off of idle, along with some idle fluctuation.

The idle does seem to be a little more stable and smoother now.

After I install the air straightener i checked my STFT and it was sitting at -23 at idle, in the process of tweaking the MAF Cal now