When things are operating properly, most drivers don’t give a second thought to what happens when pressing the accelerator pedal on a modern internal combustion engine (ICE) vehicle. Whether cable-operated or drive-by-wire, additional fuel is supplied to the engine through its fuel injectors. Equally important, the throttle body blades simultaneously pop open to deliver a larger dose of air commensurate with the increased volume of fuel to create the proper air/fuel ratio for optimum combustion.
However, if your throttle body is clogged or dirty, it throws off this balance of air and fuel. That can lead to panic-inducing stumbling, poor fuel economy, and higher emissions levels from unburned fuel exiting the exhaust. Fortunately, cleaning a throttle body is a fairly simple do-it-yourself task for anybody with even a modicum of mechanical ability. So how do you know exactly when it’s necessary?
The accumulation of dirt, grime, and carbon inside the throttle body is known as coking. This buildup results in an uneven surface that’s not exactly aerodynamic for incoming air. To visually investigate said buildup, it’s typically necessary to disconnect the air filter or air intake ducting from the front of the throttle body, then peek inside with a flashlight. However, you might also be able to tell by the ol’ “seat of your pants” indicator, too.
Rough idle or choppy performance
To answer the titular question, overall poor engine performance is the biggest sign that your throttle body may need cleaning. Specifically, keep an eye out for an unusually rough idle or in extreme cases, stalling out, which you’ll be sure to notice. Also, be alert for slower pickup or surging when attempting to accelerate.
Shrinking miles-per-gallon is another potential indicator of a dirty throttle body, and it’s also an easy metric to monitor. Your vehicle may already display instant or average fuel economy on its instrument cluster. If not, simply track the number of miles driven between fuel fill-ups and divide that number by the number of gallons purchased to calculate miles per gallon. For example, if you drove 250 miles since your last fuel stop and it takes 10 gallons to top off the tank, that equates to 25 miles per gallon. A significant drop from what’s normal could indicate trouble.
If a throttle body has become dirty to an extreme, there’s a good chance that it’ll also trigger the dreaded check engine light on your dashboard, or a similar warning message. Granted, all of the above symptoms could indicate other engine problems besides a dirty throttle body. For example, a mass airflow sensor that’s going bad. Still, it’s easy enough to visually inspect the throttle body before exploring other potentially more expensive avenues of repair.
You can also use mileage intervals
If you’re the type to perform car repairs proactively rather than wait for a symptom to present itself, you can also clean your throttle body based on mileage. Many OEM manufacturers and experts alike recommend cleaning every 60,000 to 100,000 miles. The actual process of cleaning a throttle body could be the subject of its own article, but we’ll attempt a quick rundown.
Firstly, purchase a can of aerosol cleaner specifically for throttle bodies from your local auto parts store. Next, you’ll need to remove the air duct or air filter that’s attached to the front of the throttle body. Depending on your vehicle, this could involve navigating a hose clamp or some screws. If you’re unable to easily separate the air intake tubing or filter housing from the throttle body inlet, consider taking your vehicle to a mechanic to finish the job.
With the inside of the throttle body exposed, you can get to cleaning with your choice of spray and some rags, paper towels, or even a toothbrush. Let the cleaning solution soak in for a few minutes, then hit it with some elbow grease. Be careful to wipe away any loosened dirt so it doesn’t get sucked into the engine. Reassemble and revel in your smooth idle and linear throttle response for another 75,000 miles.
