The Subaru WRX burst onto the scene as one of the leading Japanese AWD manufacturers nearly ten years ago, and is still going strong with the new 2014 WRX. Now that the platform has aged over it’s current lifespan, many a engine swappers have found early EJ20’s at a very cheap rate.
Boxer four cylinder turbocharged out of the box motors may not be as plentiful as other options, but still can be found at reasonable prices.
Today we’ll be swapping the throttle body on a EJ20 from a 2000-2005 Subaru WRX, and showing you how to service each sensor and port if needed. The majority of the work to be performed on our How To Service Your WRX Throttle Body guide is very simple and easy to do.
As always before you begin working on your car, disconnect your battery and use the utmost care with safety first in mind. If you have a factory stereo, now is a good time to find your code or retrieve it from the dealer.
Whether you are swapping the EJ20 into something or servicing your own in your 2000-2005 Subaru WRX, the throttle body can often be the source of idle surge, low vacuum or other related problems.
Here’s a view of our 2001 Subaru WRX EJ20 throttle body, shown are the coolant lines to the right for the coolant bypass.
There are two coolant lines that connect to the throttle body by depressing the clamps and sliding the hoses off. You can use a bolt to temporarily stop any leaking from these lines as you service your throttle body.Disconnect these coolant line as well as the Pressure Sensor and the Idle Air Controller ( IAC ) connectors.
Make sure to disconnect the Throttle Position Sensor ( TPS ) connector shown below, and undo the intercooler coupling that connects the throttle body to the intercooler.
After these are removed you can move onto the 12mm bolts that hold the throttle body to the intake plenum.
Once your throttle body is removed you can begin testing the various components, depending on your trouble code or problems you may be having.
How to Test the Throttle Position Sensor
Testing your Throttle Position Sensor is simple to do once you have figured out the wiring for the connector and what each one of the three pins do.
- Pin 1 – RED – Switched Power
- Pin 3 – Yellow Green – Signal
- Pin 2 – Black Green – Ground
Measuring resistance with a voltmeter can tell you whether or not the TPS is good, or simply connecting it and testing the signal wire for a 0-5 volt range will also work.
Replacement Throttle Position Sensor ( TPS ) for the EJ20 is 22633-AA140 and must be installed and adjusted using a voltmeter before reinstalling to your Subaru.
Cleaning your Idle Air Controller
The Idle Air Controller ( IAC ) is part number 22650- AA181 and employs a gasket to control the idle of your EJ20. If you are taking your throttle body off, it’s a good idea to clean this valve to ensure a steady idle and clean any gunk that may have built up in the passages.
Remove the 2 screws that hold the IAC on the throttle body, and inspect the gasket for any damage or debris that may be stuck in place.
Make sure to replace your throttle body gasket before installation and tighten to factory specifications of 15 ft lbs of torque.
Congratulations! You have now completed our How To Service Your WRX Throttle Body and ready to enjoy your EJ20 throttle body.
Happy Boosting!
