The Idle Air Controller or IAC is a crucial part of your engine’s operation, no matter what displacement, and that’s certainly true for our non turbo 2JZGE inline six. This powerplant is well known in tuner circles for having a stout bottom end and remarkable ability to respond to modifications.
While it’s not quite the over-engineered powerhouse that it’s twin turbocharged brother the 2JZGTE is, the 2JZGE is still one of the best inline six engines for forced fed operation. Bolt on turbo kits like the one we use in our How to Turbo your 2JZGE Guide can propel your stock 3.0 liter into a 450 whp monster.
But being a 2JZ doesn’t preclude it from normal maintenance problems, like idle issues that may arise from the Idle Air Controller. Today we’ll be showing you How To Test a 2JZGE IAC and check where your 2JZ idle issues may arise from.
Symptoms of a failing Idle Air Controller (IAC) can range from an engine that won’t idle or erratic idling, and can even lead to dangerous situations. The OBDII DTC Trouble Code P1652 in the Toyota 2JZ 3.0 liter engine can result from issues on the IAC.]
If you have idle problems in your 2JZGE, you can test for IAC operation simply by listening to the device on engine shutdown. Have a friend sit in the car and turn off the engine, you should hear a clicking sound as the engine dies down. You can also put your hand on the unit if it’s not too hot and feel the vibration on engine shutdown as well.
If your 2JZ IAC does not respond, check the vacuum line that runs under the intake manifold to the IAC VSV unit. If you need a How To Service your 2JZ VSV Guide, please click here.
This is the VSV valve that actuates the IAC inlet on the 2JZGE throttle body, make sure to check this unit for operation by checking out our How to Test 2JZ VSV article. The part number for this replacement is 25748-88400 from Toyota.
Using your multimeter, you are going to be measuring the resistance from PIN B1 to the pins S1, S2, S3 and S4 at the measuring temperature range. You will then be testing from PIN B2 to the same sequence of pins S1, S2, S3 and S4 for the same measurement.
At the measuring temperature of 68ºF the resistance range for this pin combination should be between 18-22 Ω. If you are not getting this resistance range, you must remove your 2JZ IAC for bench testing, or simply replace the unit altogether.
How to Remove the 2JZ IAC
The next segment of our How To Test a 2JZGE IAC will be removing the IAC for bench testing. Undo the two mounting screws on either side of the Idle Air Controller (IAC) to remove, make sure the engine is off and key is removed from the ignition.
Once you have the 2JZ IAC removed, inspect the throttle body opening as well as the IAC gasket, which should be intact. If this gasket is broken, the part number for the IAC gasket is 22278-46010. If you are replacing your IAC all together, the part number for the valve is 22270-46060.
How to Bench Test your 2JZ IAC
The 2JZ Idle Air Controller is an easy device to test if you have a voltage device that’s capable of sending power or ground to a terminal. The next part of our How To Test a 2JZGE IAC, we’ll be bench testing the IAC to see if it’s still good or worth using, otherwise we’ll be replacing it.
Inspect the back of your 2JZ IAC for any uneven wear or damage to the keyway or housing. You are going to be sending battery voltage to the terminals of B1 while grounding the S1, S2, S3 and S4 pins. You should hear and see the valve move to the open position when you do this. The next test will include the same but with the B2 pin instead of the B1 pin, make sure to ground each one of the S pins to see the valve open and react.
If you do not get any response from the 2JZ IAC, it’s time to put it out of it’s misery and yours and replace it. The replacement part number is 22270-46060 and don’t forget to replace the IAC gasket as well!
That does it for our How To Test a 2JZGE IAC article, please let us know if you have any questions or comments below!
