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Idle air control valve

Low idle

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My 2000 new beetle dies when I turn the a/c on


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.
0900c152801c00a1-nx20irngy4ugyvyt2uth3oj4-3-0.gif

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.



0900c152801c00a2-nx20irngy4ugyvyt2uth3oj4-3-4.gif
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

Aug 03, 2017 | Cars & Trucks

2 Answers

What is an IAC Valve


Google is your friend in such questions.

  • Idle air control actuator - Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Idle_air_control_actuator An idle air control actuator or idle air control valve (IAC actuator/valve) ... Idle air control actuator; MAP sensor; Mass flow sensor; Oxygen sensor; Starter motor;
  • how to tell if your iac valve is going bad - YouTube www.youtube.com/watch?v=oNO8GCN8jQA
    • BY TIMMY102345
    • 6 MIN
    • 939K VIEWS
    2009-09-07 · Video embedded · how to tell if your iac valve is going bad timmy102345. ... #372 Better repair method Toyota Camry Idle Air Control Valve - ...
  • 4 Ways to Check an Idle Air Control Valve - wikiHow www.wikihow.com/Check-an-Idle-Air-Control-Valve
    • 525K VIEWS
    2015-12-11 · How to Check an Idle Air Control Valve. ... Again, an idle air control valve can have an issue or fault without triggering a check engine light. 2.


  • There are also videos in this link. How to check and fix.

  • What is an IAC Valve Bing video

    May 12, 2016 | 1992 Toyota Paseo

    1 Answer

    Low idle below 1000 rpms dies then i have to restart periodic


    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.

    Jan 03, 2016 | Cars & Trucks

    2 Answers

    Idle speed too low at stop


    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 !

    Apr 03, 2015 | Cars & Trucks

    1 Answer

    I hooked my 95 Mazda mil up and says I need O2 sensor for bank 1 and 2 and also says I need engine speed circuit not sure wat to replace and wats really messd up please help


    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.

    Mar 30, 2015 | 1995 Mazda Millenia

    1 Answer

    Car idols rough no power


    Mar 03, 2012 | 1999 Suzuki Esteem

    1 Answer

    High idle on cold start on a 86 dodge d50 2.0 liter


    Feb 27, 2012 | 1986 Dodge Pickup 4WD

    1 Answer

    98 dodge ram 1500 5.2 the truck will start but it will not idle.


    Feb 21, 2012 | 1998 Dodge Ram 1500 4WD

    2 Answers

    On a 3.5 engine code reads low idle? any idea


    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.

    Jul 05, 2010 | Chevrolet Colorado Cars & Trucks

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