Idle air control valve

I recommend you test the idle air control valve. See procedure below. If this is not the problem, please read additional possibilities at the link below.


Operation


The Idle Air Control (IAC) valve controls the amount of air that bypasses the throttle valve, which controls the engine idle speed. The IAC valve consists of windings, an armature, a return spring, and a rotary slide. The engine control module (ECM) pulses the voltage to the winding, the opposing forces on the armature by the return spring cause it to maintain a fixed position, adjusting the amount of bypass air to maintain the correct idle speed.

Removal & Installation


Turn the ignition switch to the OFF position.
Disconnect the idle air control valve harness electrical connector.
Using a suitable tool, remove idle air control valve.
Installation is in reverse order of removal.

Testing


Checking Idle Air Control Valve (IAC) Triggering
Check IAC valve is electrically OK.
Slide up boot on the IAC valve connector.


Fig. IAC Connector
Use scan tool 'Output Diagnostic Test Mode' function 03 to trigger the IAC valve - N71.Connect VAG 1527B voltage tester, or equivalent, between terminal 1 and engine ground (GND). Voltage tester must flash.Connect VAG 1527B voltage tester, or equivalent, between terminal 2 and battery positive voltage (B+). Voltage tester must light up.If specified results are not obtained:Connect VAG 1598/19 test box, or equivalent, to ECM harness connector.Check the wiring between harness and connector terminal 1 (in engine compartment) to test box socket D11 . Then check the wiring between harness connector terminal 2 and test box socketD9 using wiring diagram. Repair as necessary.If the wiring is okay, but triggering still does not occur, replace the ECM.If the triggering signal and the wiring are okay and the valve does not react, replace the IAC valve. Checking Mechanical Function
Remove the idle air control (IAC) valve.Visually check the surface of the rotary slide (arrow) for signs of wear.




Fig. Showing the IAC Valve

WARNING
Do NOT check for ease of movement by prying on the rotary slide with a screwdriver or other tools that could cause scratching or other damage.

Reconnect the IAC valve, while still removed, to the harness connector.Use scan tool 'Output Diagnostic Test Mode' function 03 to trigger IAC valve - N71.Check whether rotary slide moves freely from stop to stop.If there are signs of scoring, or if the rotary slide does not move freely in both directions, replace the IAC valve.If the IAC valve does not respond (not triggered) during the Output Diagnostic Test Mode, check triggering. Resistance Test
Remove the idle air control valve harness connector.Use a suitable Digital Multimeter (DMM) to measure the resistance between the 2 terminals of the idle air control valve.The correct measurement should be 7-11 ohms. If not, replace the idle air control valve.
NOTE
At room temperature, the resistance value will be lower. The resistance value will be higher if the Idle Air Control (IAC) valve is measured at under-hood operating temperatures.

Reconnect the idle air control valve harness connector.The idle air control valve should hum and vibrate slightly when the ignition is turned 'ON'. If not, the ECM or harness may be defective.

Do It Yourself Diagnosis and Repair

Mark, IAC (Idle Air Control Valve), If engine is idling too fast, problem may not be the idle speed control system, but an engine vacuum leak. Check for vacuum leaks first to rule this possibility out. Also on your Toyota low coolant, air in the cooling system can cause the valve not to operate properly as I believe coolant has to run through valve for it to operate correctly. Fill/bleed air from cooling system. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
Idle Air Control Valve Toyota Nation Forum Toyota Car and Truck Forums
Troubleshoot Idle Speed Control System
Has Anyone Cleaned Their IAC Idle Air Control Valve Toyota Nation Forum...

It could be a software problem has set the idle too low or there could be a minor engine fault, blocked breather maybe or sticky egr valve.

Often this sort of problem is caused by a sticking idle air control valve or blocked or partially blocked air ports.
A can of carburettor cleaner can be used along with a stiff paintbrush and a compressed airline to clean around the throttle butterfly, the breather ports and idle control valve; removing parts as required.

Hi Rich what make model an year vehicle ? Most vehicles have a IAC valve or motor - idle air control , There is a passage in the throttle body an this valve opens an closes this passage allowing more air past the throttle plate raising the idle ! This passage gets plugged by carbon an needs cleaning to restore the idle back ! Idle Air Control Valve How to clean throttle body and Idle air control valve iac There is no means for idle adjustment , the engine PCM controls It !

First is all always write down the codes you have present, it helps in closing down on the problem. I am assuming you have a 95 Mazda Milleinia

1. Start and run the engine and monitor the oxygen sensor signals and see if this sensor has bad readings still. Check for an open or shorted wire between the sensor and the Engine Control Module (ECM) if the signal is dropping out.

2. Listen for an exhaust leak in the area of the oxygen sensor, the leak could allow oxygen in to the exhaust and skew the sensor readings.

3. Inspect the ECM and ECM connector for signs of something that has been spilled on the ECM. Is the engine idling too high or too low then check this:-
1. Unplug the idle air control valve and turn the air bypass screw in to see if it will idle down. If it will idle down, adjust the idle speed to around 500 RPM's and then plug the idle air control valve back in.

2. If it still idles high, remove the air boot from the throttle body, block the air bypass ports with duct tape, hook the air boot back on and start it. This should make it not idle at all or just barley idle. If it does, the problem is in the idle air control valve.

3. If blocking the air ports doesn't cause it to idle down, the throttle plate must be sticking open. Clean the throttle plate really good and back the throttle stop screw off and then see if it idles down.

4. Verify the coolant level is not low and that coolant is circulating through the idle air control valve. Tech Tips: This idle air control valve is two valves in one. It is a fast idle thermo valve on one side and a duty cycle idle air control valve on the other.

I’m happy to assist further over the phone at https://www.6ya.com/expert/uttamjeet_2f3adc18600f8ede

For rough idle issues and problem troubleshooting,go through the help links provided below :----- van idles rough?

http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html

---------
will not idle when cold?

http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html

----------
runs lean and idles rough?

http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html

-----------
Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

------------
Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

----------
Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

---------
Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

-----------
Replace Idle air control valve?

---------
Test Idle Air Control (IAC) Valve?

-------
Idle Air Control (IAC) Valve operation?

----------
Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

------------
Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

------
While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

---------

This will help.

Thanks.

For rough idle issues and problem troubleshooting,go through the help links provided below :-----van idles rough?

http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html

---------
will not idle when cold?

http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html

----------
runs lean and idles rough?

http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html

-----------
Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

------------
Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

----------
Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

---------
Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

-----------
Replace Idle air control valve?

---------
Test Idle Air Control (IAC) Valve?

-------
Idle Air Control (IAC) Valve operation?

----------
Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

------------
Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

------
While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

---------

This will help.

Thanks.

For idle issues and problem troubleshooting,go through the help links provided below :----- van idles rough?

http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html

---------
will not idle when cold?

http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html

----------
runs lean and idles rough?

http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html

-----------
Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

------------
Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

----------
Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

---------
Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

-----------
Replace Idle air control valve?

---------
Test Idle Air Control (IAC) Valve?

-------
Idle Air Control (IAC) Valve operation?

----------
Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

------------
Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

------
While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

---------

This will help.

Thanks.

could be vacum line leak or leak elswhere

LOW IDLE CAN BE CAUSED BY MANY THINGS.CLOGGED AIR FILTER. LOW COMPRESSION OR MISFIRE CONDITION.IDLE AIR INLET PASSAGE OR THROTTLE BORE IS DIRTY OR FULL OF DEPOSITS.IDLE AIR CONTROL VALVE FAILED.MASS AIR FLOW SENSOR COULD BE OUT OF CALIBRATION. THROTTLE PLATE THROTTLE SHAFT OR LINKAGE IS DAMAGED OR STICKING.PROBABLY HAVE REMOVE THROTTLE BODY ASSEMBLY REMOVE IDLE AIR CONTROL VALVE AND THROTTLE POSITION SENSOR.BUY CAN OF CARBURETOR OR THROTTLE BODY CLEANER SPRAY CLEAN ALL CARBON BUILT UP AROUND THROTTLE PLATES AND BORE.LET AIR DRY BUY A NEW THROTTLE BODY GASKET.