Symptoms of a Bad or Failing Idle Air Control Valve

Your idle shouldn’t waver like a politician’s stances.

An idle air control valve placed against a white backdrop.
Amazon / Motoall

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Intro: A graph of your car’s idle speed shouldn’t resemble architectural plans for a new Cedar Point roller coaster. Once the car warms up to normal operating temperature, it should run in a smooth consistent line.

Should your idle develop a nervous quibble, it’s one way your car is telling you that there’s a problem that needs resolving. Idle problems can often, but not always, stem from a failing or clogged idle air control valve, a small part adjacent to the throttle body that does exactly what its name indicates. Fortunately for the garage greasers out there, it’s typically a fairly easy part to access, service, and replace.

To help those who aren’t as grubby as we are, The Drive has put together a helpful, but to-the-point, guide with everything you need to know about idle air control valves. Let’s get to it.

What Is a Car’s Idle?

The idle speed is the speed at which your engine is operating while the car is operating without any throttle inputs. The car’s idle speed is displayed in revolutions per minute (RPM) on the tachometer in the dashboard gauge cluster. Simply put, when you’re in park and start the car, the car is then idling.

What Is a Normal Idle Speed?

The typical consumer car will idle somewhere in the range of 500-1000 RPM, depending on the vehicle. It might also start at a higher RPM, by 100-300 RPM, before dropping down to its normal operating speed. Consult your owner’s manual to find your specific car’s normal speed.

High-strung performance cars may have higher idles, and motorcycles have idles that range between 2,500-4,000 RPM. 

What Is an Idle Air Control Valve? 

There aren’t many car parts that are as accurately named as the idle air control valve. It is a valve or a device that opens and closes to release air or fluid flow (air in this case) into the engine. 

What Is an Idle Air Control Valve’s Job?

The idle air control valve controls the air needed to maintain a steady idle speed. It essentially acts as a bypass of the throttle body plate.

A black idle air control valve sits over a white backdrop.
Amazon / GM

The solenoid in an idle air control valve can get stuck.

Where Is the Idle Air Control Valve Located? 

The idle air control valve is typically found attached to the throttle body.

Most Common Idle Air Control Valve Issues 

Two common issues can arise in an idle air control valve, clogging and failing, and each requires your adept wrenching hand at fixing. 

Clogged

Due to the flow of air in and out of the idle air control valve, it’s possible for contaminants to enter the valve chamber. These particles or contaminants could clog, jam, or damage the part’s internals and cause an improperly functioning valve.

Failing

If the solenoid inside the idle air control valve fails, the valve no longer receives an electrical signal, or seals wear down, the valve won’t be able to do its job, and the car likely won’t be able to start.

Symptoms Of a Clogged or Bad Idle Air Control Valve

There are several ways your vehicle could tell you its idle air control valve is in trouble. Know, however, that these symptoms are quite general and are not 100% accurate diagnoses. If you inspect, clean, or replace, your valve, the idle issues might persist due to other problems within the engine.

Trouble Starting

If an engine isn’t getting enough air, it might not start or will have difficulty starting. This could indicate an issue with the idle air control valve.

Poor/Rough Idling

When the source of air into the engine is inconsistent, it will create a glugging, hesitating, and revving and dying sound. You’ll know something is up.

Car Starts, Then Dies

If the valve works occasionally, or it only works in certain parts of its cycle, the car might be able to start before it starves of air and dies.

Backfiring

If the engine doesn’t have enough air, the air-to-fuel mixture ratio is off, and some fuel might be left after the spark. This fuel then makes its way through the system and could cause a backfire.

A tubular idle air control valve is pictured against a white backdrop.
Amazon

If an idle air control valve fails, it will cause your car to idle poorly.

Basics of Replacing an Idle Air Control Valve

Estimated Time Needed: 30 minutes to an hour

Skill Level: Beginner

Vehicle System: Engine

Idle Air Control Valve Safety

Working on your car can be dangerous and messy, so here’s exactly what you’ll need to ensure you leave the garage in the same condition in which you entered.

Everything You’ll Need To Change the Idle Air Control Valve

We’re not psychic, nor are we snooping through your toolbox or garage, so here’s exactly what you’ll need to get the job done.

Tool List

  • Wrench or ratchet set
  • Scraping device or flathead screwdriver
  • Philips screwdriver (if necessary)

Parts List

  • New idle air control valve
  • New gasket

Organizing your tools and gear so everything is easily reachable will save precious minutes waiting for your handy-dandy child or four-legged helper to bring you the sandpaper or blowtorch. (You won't need a blowtorch for this job. Please don’t have your kid hand you a blowtorch—Ed.)

You’ll also need a flat workspace, such as a garage floor, driveway, or street parking that’s also well-ventilated. Check your local laws to make sure you’re not violating any codes when using the street because we aren’t getting your ride out of the clink.

Here’s How To Change an Idle Air Control Valve

It’s easy, let’s do this! 

  1. With the vehicle cooled down in an out-of-the-way spot, pop the hood and locate the idle air control valve. 
  2. Remove any parts that are in the way of accessing the idle air control valve. 
  3. Unplug the electrical connector on the idle air control valve. 
  4. Remove the idle air control valve.
  5. Remove the gasket and make sure no gunk is left behind. 
  6. Bolt on the new idle air control valve with a new gasket.
  7. Reattach the electrical connector. 
  8. Put any removed parts back in place.

That’s it, let’s hope that was the problem!

Get Help From a Mechanic On JustAnswer

Although The Drive’s detailed how-to guides are easy to follow, a rusty bolt, an engine component not in the correct position, or a messy oil leak can derail a project. That’s why we’ve partnered with JustAnswer, which connects you to certified mechanics around the globe, to get you through even the toughest jobs. 

So if you have a question or are stuck, click here and talk to a mechanic near you. 

FAQs

You’ve got questions, The Drive has answers!

Q: Can You Drive With a Bad Idle Air Control Valve?

A: Can you? Yes. Should you? No. If there is an issue with a vehicle, we always recommend fixing it before driving with it.

Q: Can You Adjust the Idle Air Control Valve? 

A: Throttle adjustment and calibration is best done with a machine with numerical readouts, a tool primarily owned by professionals.

Q: How Do I Clean My Idle Air Control Valve Without Removing It?

A: The valve is not very difficult to remove, in most cases. We recommend removing it and cleaning it the correct way.

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