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.
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.
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.
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.
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.
The idle air control valve is typically found attached to the throttle body.
Two common issues can arise in an idle air control valve, clogging and failing, and each requires your adept wrenching hand at fixing.
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.
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.
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.
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.
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.
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.
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.
Estimated Time Needed: 30 minutes to an hour
Skill Level: Beginner
Vehicle System: Engine
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.
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.
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.
It’s easy, let’s do this!
That’s it, let’s hope that was the problem!
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.
You’ve got questions, The Drive has answers!
A: Can you? Yes. Should you? No. If there is an issue with a vehicle, we always recommend fixing it before driving with it.
A: Throttle adjustment and calibration is best done with a machine with numerical readouts, a tool primarily owned by professionals.
A: The valve is not very difficult to remove, in most cases. We recommend removing it and cleaning it the correct way.
We’re here to be expert guides in everything How-To related. Use us, compliment us, yell at us. Comment below and let’s talk! You can also shout at us on Twitter or Instagram, here are our profiles.
Jonathon Klein: Twitter (@jonathon.klein), Instagram (@jonathon_klein)
Tony Markovich: Twitter (@T_Marko), Instagram (@t_marko)
Chris Teague: Twitter (@TeagueDrives), Instagram (@TeagueDrives)
Dewalt Mechanics Tools Kit and Socket Set
RevHeads Safety Gloves
Black+Decker Cordless Drill
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