Erratic engine idle

GDAWNIELLE

MEMBER
2001 BUICK PARK AVENUE
6 CYL
AUTOMATIC
122,000 MILES

The car runs great while in motion. As soon as I start to press the break, the idle drops and stalls this happens during turns and coming to complete stops. When I start the car and it idles while in park you can hear the engine revving up and down but the rpm never goes over one but it drops and the engine revs up to bring it back up to the 1. I had it hooked up to the diagnostic machine. It said the oxygen sensor but that was just replaced.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,645 POSTS

Hi,

What you described sounds like a faulty idle air control valve (IAC). The IAC is responsible for maintaining the engine idle speed under all conditions.

The IAC is located on the throttle body. What I would suggest is to first remove and inspect it. Make sure there is no carbon build up where it mounts as well on the pintle. I am going to provide the directions for replacement. However, don't just replace it without making sure it isn't a dirt / carbon issue.

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First, here is a link that shows in general how to replace one and one showing how to service one:

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

https://www.2carpros.com/articles/idle-air-control-valve-service

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Here are the directions specific to your vehicle. The attached pics correlate with the directions.

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2001 Buick Park Avenue V6-3.8L VIN K
Idle Air Control (IAC) Valve Replacement
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Speed/Throttle Actuator - Electronic Service and Repair Procedures Repair Instructions Idle Air Control (IAC) Valve Replacement
IDLE AIR CONTROL (IAC) VALVE REPLACEMENT
IDLE AIR CONTROL (IAC) VALVE REPLACEMENT

REMOVAL PROCEDURE

pic 1

1. Remove the fuel injector sight shield.

pic 2

2. Remove the idle air control valve electrical connector from the idle air control valve.

pic 3

3. Remove the two idle air control valve attaching screws.

pic 4

4. Remove the idle air control valve from the throttle body.

pic 5

5. Remove the idle air control valve O-ring from the idle air control valve.
6. Inspect the idle air control valve O-ring for cracks or damage. Replace the idle air control valve O-ring if necessary.

INSTALLATION PROCEDURE

NOTE: The IAC valve may be damaged if installed with the cone (pintle) extended more than 28 mm (1 - 1/8 in). Measure the distance that the valve is extended before installing a new valve. The distance from the idle air control valve motor housing to the end of the idle air control valve pintle should be less than 28 mm (1 - 1/8 in). Manually compress the pintle until the extension is less than 28 mm (1 - 1/8 in).

pic 6

1. Install the new idle air control valve O-ring to the idle air control valve.

pic 7

2. Install the idle air control valve into the throttle body.

NOTE: Refer to Fastener Notice in Service Precautions.

pic 8

3. Install the idle air control valve attaching screws.

Tighten
Tighten the bolts to 3 N.m (27 lb in).

pic 9

4. Install the idle air control valve electrical connector to the idle air control valve.
5. The PCM will reset the idle air control valve whenever the ignition is turned ON, then OFF. Turn the ignition ON, then OFF.
6. Start the engine and allow the engine to reach operating temperature.

pic 10

7. Install the fuel injector sight shield.

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Let me know what you find or if you have other questions.

Take care,
Joe

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