Project E46 M3: Part 11 – Castro Motorsports air box installed and dyno tested!


To make room, you’ll have to disconnect the driver-side xenon ballast, which is very easy.  Just pry off the plastic cover and remove the two connectors.

With the air filter box out, some space will be freed up.  Next, remove the 10mm nut holding in the dipstick., and disconnect the vacuum line next to it by pulling on it.  This would also be a good time to check your power steering fluid level by opening the asterisk-shaped cap on the power steering reservoir you see here just aft of the alternator.

Before we start removing the obvious hose clamps we see on the intake runners, which secure the intake, we'll want to remove the cowl.  This is so we can access the back runners for cylinders 5 and 6 more easily.  There's our AEM MAP sensor in the back, which removed the need to run our HFM.  Something to keep in mind is that, in order to run any airbox of this type, you'll need to convert to either Alpha-N or MAP sensor since the factory HFM is removed.

You’ve seen how easy it is to remove the cabin air filter in Part 1 of this project series.  We'll need to continue with a Torx25 driver and remove the four bolts holding the cowl on.  It will be pretty self explanatory when you get to this postion.

For some reason it seems many people online were having problems removing these factory, single-use clamps.  For us, just a couple of screwdrivers pressing together did the trick.  The clamps came off very easily.  However, we did opt to replace them with new ones.

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