[ Article from 2004 ]

I recently had the pleasure of replacing my throttle body. In the process, I learned plenty about the setup that I can share with you.

Disclaimer: I can only confirm these instructions and torque specs for the 2002-2004 non-STI WRX models. Using these instructions on any other model could be problematic. For instance, I know for sure that the 2004+ STI torque spec for the 4 TB mounting bolts is 1/4th of what it is for the WRX.

The Pieces

• A - Idle Air Control solenoid valve and gasket directly on top of main chamber (2 screws)
• B - MAP sensor located on the top left (2 screws)
• C - Throttle Position Sensor located low on the driver’s side (2 screws)
• D - Coolant line attached to driver’s side with spring-loaded hose clamp
• E - Coolant line attached to bottom side with spring-loaded hose clamp
• F - Throttle body to intercooler hose (2 hose clamps)
• G - Gasket between throttle body and intake manifold

Removal

NOTE: Before you remove anything, it is recommended by Subaru that you prepare to use a replacement gasket for the throttle body.

NOTE: If you remove the Idle Air Control solenoid valve from the top of the throttle body, replace the rubber gasket inside. I didn’t, and sucked quite a bit of coolant into my engine before I wised up — not good.

NOTE: During this job, I tore the heads of two sensor screws due to the force needed to break them free from their factory over-tightened state! Be prepared for some trouble. I ended up having to ride my bike to True Value to find replacements.

Tools needed: 1 rag, pliers, socket wrench, 12mm deep socket, large flat-head screwdriver, 10mm short socket or preferably a 10mm GearWrench (for the 3 breather line screws in the front of the intercooler)

1. Let the engine cool. Your coolant should be cool/warm and no longer under pressure.
2. Remove the intercooler and thoroughly clean the bolts (they will be used in a bit to plug the TB coolant lines)
3. Remove the intercooler-to-TB hose and hose clamps
4. Unplug all 3 sensors (A, B, C)
5. Disconnect the throttle and cruise cables by pulling each spring-loaded assembly toward the front of the car, then pushing the small cylinder at the end of the cable out of its housing. You should see what I am talking about. It is not difficult, and is just like a bicycle’s brake cable set up. Holding the spring-loaded housings for 10-20 seconds while you unlatch the cable can start to become…uncomfortable. You might want to put a work glove on your pulling hand.
6. Using pliers, compress the coolant line hose clamps and slide them down each respective hose about 2-3 inches. Don’t worry, the hose shouldn’t pop off the TB without effort.
7. Now, one by one, remove the 2 coolant lines from the TB. Plug the ends of the hoses with your clean intercooler bolts. Use your rag to dab up any coolant that may have dribbled around - no big deal.
8. Unbolt the 4 bolts holding the TB to the intake manifold
9. Set the TB aside and remove the TB-to-manifold gasket
10. If you’re going to have the TB off for more than 10 minutes or so, I highly recommend finding a very clean rag to stuff in the intake manifold opening. Better safe than sorry.

Installation

Reverse the order of removal, but be very careful not to overtighten any bolts. The torque specifications are as follows:

1. 4 bolts holding TB to intake manifold = 15.9 ft/lb (22 N-m)
2. MAP sensor screws = 1.2 ft/lb
3. Idle Air Control solenoid valve screws = 2.1 ft/lb
4. Throttle Position sensor screws = 2.1 ft/lb

You may need to bleed your coolant system afterward (unlikely).