The Volkswagen Jetta has a 2.0-liter engine that produces about 150 horsepower. Because the car is so light, this amount of power is more than adequate. However, there is a simple upgrade you can do to boost the horsepower up as much as 15 extra horses. Installing a cold air intake system is a great way to improve the performance of the Jetta's engine. The upgrade will also improve the gas mileage.
Use a wrench to loosen the battery's connection cables and disconnect the battery from the vehicle to avoid potential shock. Remove the four screws on top of the radiator support with a screwdriver and remove the plastic cover from the radiator.
Unplug the wire harness from the intake hose and remove the hose clamp from the intake. Pull the rubber intake hose out of the manifold.
Pull the breather hose off of the air box. Use a ratchet to remove both of the bolts that hold down the stock air box and pull up firmly to remove it from the car. Remove the last nut that secures the stock duct to the fender.
Use a screwdriver to remove the four bolts that secure the battery tray in place then pull it up and out of the engine compartment. Gently pull the wire harness out of the fender well. Clip the harness onto the other side of the grounding wire.
Remove the five screws that hold the plastic wheel liner to the wheel well with the screwdriver. Pull off the plastic cradle that holds the harness in place. Pull off the final two plastic rivets located on the radiator. Pull off the plastic rivet on the driver's side underneath the headlight.
Pull off the plastic guard that was loosened by removing the screws and rivets. Secure the cold air intake's rubber mount to the hole underneath the battery tray. Reinstall the temperature sensor (the wire harness from Step 2) by pushing it into place then attach the cold air intake coupler to the end of the sensor.
Place one of the intake's washers onto the stud that the air duct was previously mounted to. Connect the intake tube to the sensor's coupler and secure it with the hose clamp. Secure the lower part of the tube to the stud with the washer on it and to the rubber mount installed in Step 6.
Install the conical filter to the lowest end of the intake tube and secure it with the hose clamp. Connect the breather hose to the cold air intake's hose adapter. Place the vacuum hose onto the main air intake tube and press it down firmly.
Reinstall the wheel liner with the screws and the headlight bolt. Reinstall the battery tray and reconnect the battery to the car.
