1999.5 - 2005 Volkswagen Golf/GTI 2.0L 4 Cyl. Cold Air System Installation

Installing the AEM Cold Air System
a) When installing the AEM intake, DO NOT completely tighten the hose clamps, MAF sensor assembly or the mounting tab hardware until instructed to do so later in these instructions.
b) Install the rubber mount in the outermost (towards driver’s side of vehicle) hole to the rear of the large opening behind the headlight. Insert the rubber mount from below (Fig. 16) and secure it with a large fender washer and lock nut from the top. (Fig. 17)
c) Place a large fender washer on the stud that originally secured the lower intake tube in place. (Fig. 18)
d) Re-install the MAF sensor into the plastic intake hose, rotating the electrical connector to the original position. Use the original spring hose clamp. Note: it is possible to install the MAF sensor backwards. DO NOT INSTALL BACKWARDS. Make sure that the end with the flange (originally in the airbox) is still facing away from the throttle body. If you are still unsure, there is an arrow with the word “flow” molded into the MAF sensor body. (Fig. 19)
e) Install the silicone hose onto the upper end of the AEM inlet pipe with one of the 2.75” hose clamps. The upper end is the end with the AEM decal. Loosely install the second 2.75” hose clamp onto the silicone hose.
f) Feed the AEM inlet pipe into the engine bay and fender well. The lower bracket should line up with the rubber mount installed in step 3b. The upper mount should line up with the stud originally used to mount the lower intake tube.
g) Install a large fender washer and lock nut onto both the rubber mount and the stud. (Fig. 20 & 21) Refer to the following diagram for proper rubber mount installation.
h) Insert the MAF sensor into the into the silicone hose on the AEM inlet pipe. Make sure the MAF sensor is still rotated correctly in the factory position. Plug in the MAF sensor wire connector.
i) Install the AEM air filter onto the bottom of the AEM inlet pipe using the supplied hose clamp. Make sure the filter does not contact the horn or the plastic fender liner. (Fig. 22)
j) Adjust the inlet system for best fitment and snug the hose clamps and locknuts down. (Make sure that no part of the inlet system comes into contact with any part of the vehicle.)
k) Connect the factory breather hose to the AEM vacuum hose adapter. Line the clips on the plastic hose up with the flats machined into the adapter. (Fig. 23) It may be helpful to lubricate the o-ring with a small amount of clean engine oil. Use caution to avoid damaging the o-ring.
l) Install the supplied 5/8” vacuum hose section from the AEM adapter to the nipple on the back of the AEM inlet pipe with the two supplied 1” hose clamps. Route the hose in a broad arc under the AEM inlet pipe to avoid kinks. (Fig. 24)
m) Re-assemble the vehicle in the reverse order of disassembly. The large plastic cover behind the headlights that was retained by the three plastic rivets does not need to be reinstalled.
n) At this point the entire intake tube and filter can be re-adjusted for position and alignment. Make sure that no part of the AEM intake rubs anywhere along its length. Critical points to check are on the corner of the plastic battery box and at the bend in the pipe just above the air filter.

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