IAC Valve

It just unbolts. Unplug the wiring harness, and have the parts store recommend a good cleaner they have for it. I will say that usually, when they go bad, they are bad. Here are directions for checking it.

Let me know if it helps.




The Idle Air Control (IAC) valve is used to control idle speed. The amount of air allowed to bypass the throttle plate is determined by the PCM.

When the engine is cold, air flows through the valve during all modes of engine operation to maintain the factory set idle speed.


Testing

1.8L Engines





Fig. Typical IAC valve wiring schematic and connector terminal identification-1.8L engines

1.Turn the ignition key OFF.
2.Connect jumper wires from the sensor connector to the wiring harness. This permits the engine to operate normally while you check the sensor.
3.Connect a Digital Volt Ohmmeter (DVOM), set to read resistance, between sensor terminal SIG and the negative battery cable.
4.The resistance should not be greater than 10,000 ohms.
5.Connect the DVOM, set to read resistance, between sensor terminal VPWR and the negative battery cable.
6.The resistance should not be greater than 10,000 ohms.
7.Turn the ignition key ON.
8.Connect the DVOM, set to read voltage, between sensor terminal VPWR and the negative battery cable.
9.The voltage should be more than 1 volt.
10.Connect the DVOM, set to read voltage, between sensor terminal SIG and the negative battery cable.
11.The voltage should be more than 1 volt.
12.If the readings are not within specifications, replace the IAC valve.


1.9L And 2.0L Engines





Fig. IAC valve (solenoid) connector terminal locations-1.9L and 2.0L engines

1.Turn the ignition key OFF.
2.Unplug the sensor electrical connection.
3.Due to the diode in the IAC valve, be sure to observe the correct polarity when connecting the DVOM.
4.Connect a Digital Volt Ohmmeter (DVOM), set to read resistance, between the sensor terminals as follows. Connect the positive lead to the VPWR terminal and the negative lead to the IAC terminal.
5.The resistance should be between 6 and 13 ohms.
6.Measure the resistance between either of the valve terminals and the valve body. The resistance should be greater than 10,000 ohms.
7.If the resistances are not within specification, replace the sensor.




Fig. Connect the DVOM positive lead to the VPWR terminal and the negative lead to the IAC terminal. The resistance should be between 6 and 13 ohms






Fig. Measure resistance between either of the valve terminals and the valve body. The resistance should be greater than 10,000 ohms

Thanks for your prompt reply, problem with my Focus is on hot summer day after a long drive or after crawling in heavy traffic for good half hour or so and after I make a stopover for few minutes, then when I restart it won't idle. I have to hold gas pedal well above 1000 rpm,funny thing is on thursday I went back to coffee shop for about 20 mins then it was fine and according to few guys on the forum of focus fanatic says its IAC Valve and its very tough to get to it because it comes out of under side and you have to jack up car to get at it.

What I meant was when engine hot on very hot day about 90F and you stopover after a long drive preferably after crawling in heavy traffic. Comeback in few mins car starts fine but it wont idle, but what I did once is there was a coffee shop beside where I was and all I did was went to have a coffee spent good 30 mins or so then restart the car and idle just fine normal.

I think that is where the problem is coming from.

where is the valve located and how would i go about cleaning it? i realize i probably will end up replacing it but i would like to try to clean it first.

On the intake up by the throttle held on by couple torx heads. Make sure you clean out passage in throttle body.