Cleaning the Throttle Body

by Josh Baum

A car's throttle body generally requires very little maintenance, and many cars can run well over 100,000 miles without a throttle body cleaning. However, thoroughly cleaning the throttle body every 75,000 miles or so can greatly improve long-term gas mileage, engine performance and engine wear. It's also easy to do at home with basic tools.


The throttle body is connected to the gas pedal of a car through a direct linkage. When the gas pedal is depressed, a disc turns inside the throttle body, allowing fuel to be dispensed into the engine. Over time, the gases expelled during the combustion process waft up into the throttle body and create a layer of deposits on the inside. This can eventually cause stalling, stuttering and poor fuel economy if the buildup is extensive.


The throttle body typically bridges the gap between the engine's intake manifold and the air filter. It's often a wide, aluminum cylinder that also has electrical wires and smaller hoses coming out of it. A long, thin arm also connects the throttle body to the gas pedal linkage, so if you can't spot the throttle body just by looking, have someone press down on the gas pedal while you're looking under the hood. You'll see the arm move, leading you to the throttle body.


All of the smaller hoses on the throttle body must be removed. These are often attached with hose clamps that are tightened by screws, or the hoses and plugs are contoured specifically to fit together tightly. Hose clamps must be loosened with screwdrivers and removed, but contoured hoses can just be carefully pulled off. A large hose clamp usually connects the throttle body to the larger air filter hose. Remove this hose clamp, then pull the throttle body away from the air filter by a few inches. Don't disconnect the electrical wires.


Spray a small amount of aerosol carburetor cleaner into the air intake valve of the throttle body, then use a small, stiff-bristled nylon brush to scrub away at the gas deposits. After every minute or so of scrubbing, wipe the inside with a clean paper towel to remove the loosened buildup. Spray additional carburetor cleaner as needed and continue scrubbing and wiping until the inside of the throttle body is completely clean.


Reconnect the air filter hose and all of the other hoses the same way you disconnected them. Use the original hose clamps and make sure they're all installed tightly. If your throttle body has contoured hoses that snap into place on the throttle body, make sure they're pushed all the way down by tugging on them lightly.


Start the engine and take the car on a short drive immediately after cleaning. This will circulate some fuel through the throttle body and flush out any remaining carburetor cleaner. Because of the leftover cleaning agents, the first few miles may bring some engine stuttering or stalling. This is normal. After a few miles of driving, everything should be back to normal, provided you reconnected all of the hoses properly.


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