Scion XB Forum banner
1 - 2 of 2 Posts

266 Posts
Discussion Starter · #1 ·
Hey guys (and gals). This DIY guide will show you how to safely remove the stock air box from the 2008 Scion xB, as well as how to install the Weapon-R Secret Weapon intake. For the most part, these instructions can be adapted for use with any intake system. That being said, I'm fairly new to the tuner world so I've probably made up my own names for some of the parts, but the pictures should clearly illustrate what I'm referring to in each step. I can edit the pics and steps if anyone can give me some recommendations on how to make this guide more professional and/or easier to understand.

Allot yourself about two hours of time if you're new to under-the-hood work like I am. It took me about that long while taking pics and searching for tools. Before you attempt installation, make sure you choose a stable, dust-free and debris-free environment -- preferably an auto garage. The installation shown here took place out in my driveway in the blistering cold. Probably not the best idea. Remember kids, "Don't Do What Donny Dont Does!"

Tools Required:
  • Standard Philips Head Screwdriver
  • Standard Flat Head Screwdriver
  • 10mm Socket Driver
  • T15 Torx Screwdriver (If you dont have one you can pick one up at Sears for about $2)
  • Pliers (They need to grip pretty far, don't use needlenose!)
  • Scissors

Step 01: Remove the Engine Cover
This is what it looks like underneath the hood of the '08 xB. Use the 10mm socket driver to remove the two screws shown, and lift off the engine cover. Set them aside and do not lose the screws; you will need them later.

Step 02: Remove Airflow Sensor and PCV Hose
Use a standard philips head screwdriver to remove the two screws securing the airflow sensor. Put the screws in your used parts box, they will not be used again. Next unfasten the PCV hose clip and set it aside. Trace that hose down the line and you will find a second clip securing the PCV hose to the air hose, set it aside as well. You will need them later on. Put the PCV hose in your used parts box.

Step 03: Air Box Cover Clip Locations
Unfasten the three clips pictured.

Step 04: Remove the Air Box Cover
Loosening the screw pictured should allow you to remove the air box cover from the air hose now that the clips are removed. Place the air box cover and the white air filter in your used parts box.

Step 05: Remove the Air Box
With the air filter removed, the three screws securing the air box to the engine compartment should be exposed. Use your 10mm socket driver to remove them. Set two of the screws aside, they will be used later. Place the other screw in your used parts box. You will have to jiggle the air box free of the intake hose. Put the air box in your used parts box.

Step 06: Remove Air Flow Sensor Assembly from Air Hose
You will need to force the clip shown in the picture through the rubber it is attached to. The rubber is a part of the air hose which will not be used anymore, so do not worry too much about being gentle. Besides, the rubber is very tough.

Step 07: Remove Air Hose
The final step in the removal of the stock airflow system is to disconnect the air hose from the throttle body. This is accomplished by squeezing the protruding pieces of the throttle body clamp with pliers while jiggling the air hose off. Save the clamp as it will be used later. Place everything else you have in your used parts box.

Step 08: Stock Airflow System Removed
This is what your engine compartment should currently look like. Labeled are a few parts that will be worked on in the next steps.

Step 09: Get Your Parts Ready
Pick up the throttle body clamp you set aside, and grab the 2.5" to 3" adapter from your Weapon-R kit. There are two very similar adapters in the kit. This picture should make it clear which to use as they are not labeled.

Step 10: Secure the Adapter to the Throttle Body
Wipe any grease and/or dirt from the lip of the throttle body before putting the adapter on. The small side goes on the throttle body. You will have to hold down on the clamp's protruding ends with your pliers once again to get the clamp and adapter on. If your Weapon-R kit came with four Weapon-R screw clamps, you can use one of them instead of the OEM clamp.

Step 11: Install Intake Tube
Take your silver intake tube and install the end with the PCV hose connection closest to it in the 3" side of the Weapon-R adapter, securing it with a Weapon-R clamp. Rotate the screw clockwise until tight. The intake pipe should be able to stand up on its own if everything is secured properly.

Step 12: Reinstall the Airflow Sensor, Add the Bracket and Second Adapter
First, remove the two screws from the top of the intake pipe with your T15 screwdriver. Place the airflow sensor in the provided hole and screw it in tightly using the two torx screws just removed. Next, hook the provided bracket underneath a clamp, and then use the clamp to secure the 2.75" to 3" Weapon-R adapter to the intake tube. The 2.75" side of the adapter goes on the intake tube. Screw it tight. The second picture was taken after install and should clarify how to hook the bracket to the clamp.

Step 13: Bend and Secure the Weapon-R Bracket
Bend the Weapon-R provided bracket installed in the previous step to a 90 degree angle to line up two of the screw holes with two screw holes where the air box used to sit. Secure the bracket with the two screws set aside in step 5.

Step 14: Install Air Filter and PCV Hose
Insert the air filter into the 3" end of the Weapon-R adapter, securing it with a Weapon-R screw clamp. Next, take the Weapon-R PCV Hose and cut it to approximately 11". Use the two clips set aside in Step 2 to secure it. If there are any kinks in the hose, cut about 1/4" lengths from one end until they disappear. Your hose should look like pictured when installed.

Step 15: Reinstall the Engine Cover
Rotate the PCV hose clip so that it does not point straight up or it will get in the way of putting the engine cover back on. Line up the two holes on the engine cover to the two posts on the engine. Reinstall the screws removed in step 1 and you're done! Congratulations, turn on your car and let it idle for about 5 minutes as the ECU adjusts to the airflow sensor's new readings. You should have no extra lights on your dash, check engine or otherwise. I did not. Here's a snapshot of the finished product!

I will be turning these instructions into PDF format after I get some feedback from the community. Anyone know a free permanent place I could host the file similar to

266 Posts
Discussion Starter · #6 ·
wow now thats how all DIY should be done....good does the intake sound? do you hear it alot more now?
The nice thing is if I take off slowly I can't notice the intake really. However, if I hit high rpms or accelerate quickly, YEAH you can really hear the intake, and it's a really sweet sound!

JOEY G-xB said:
i have seen the Secret Weapon intake advertised with a Ram-Air kit... Did you get that with your intake... just curious?
Yes, mine came with a ram air kit and a free air filter cleaning kit. When I purchased it, it wasn't advertised to come with it, but I got it anyway without asking for it. Truth is I didn't even know what it was at first! I didn't install the ram air kit, and don't have any plans to do it really soon. I'm going for that better-than-stock approach, but not too overly concerned about squeezing every last little ounce of hp out of my car.
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.