Rick's Free Auto Repair Advice

Throttle body cleaning

Throttle body cleaning — step by step

If you own a late model fuel injected vehicle, chances are it has an electronic throttle body. They can suffer from carbon buildup just like the older idle air control valve, so you may need to do a throttle body cleaning procedure.

What causes carbon buildup in the throttle body?

Crankcase gasses cause throttle body carbon buildup

When you shut down the engine, crankcase vapors rise to the top of the engine. From the valve cover, the vapors make their way into the intake manifold and the throttle body. The vapors contain exhaust, soot, water vapor and some unburned fuel. As the engine cools, those vapors condense on the intake side of the throttle body, especially near the throttle plate. The carbon buildup hardens as it cools. As the buildup increases, it reduces airflow through the throttle body.

How to perform a throttle body cleaning

It’s fairly easy to clean a mechanical throttle body while it’s still on the engine. But you should never try cleaning an electronic throttle body while it’s on the engine. You must remove it an clean it off the vehicle. Here’s why:

An electronic throttle body is built with a powerful motor and a gear reduction set that’s strong enough to cut off your fingers! If you force the throttle plate open while the unit is on the vehicle, it will try to close and may cause injury. In addition, you need access to the backside of the throttle plate, something that’s impossible to clean while it’s still on the vehicle.

Supplies you need to do a throttle body cleaning

• New throttle body gasket
• Aerosol can of throttle body cleaner, and a clean ragthrottle body cleaner
• Socket set
• Pliers

Electronic throttle body cleaning— Step 1: Disconnect and label hoses

WARNING: Do NOT use carburetor cleaner. The solvents in carb cleaner can damage some of the plastic parts used in an electronic throttle body.

• Find and label all small vacuum hoses going to the throttle body. If you don’t do that now, you may forget which ports they attach to. Use removable (blue) masking tape and number both the hose and the port using a sharpie marker.

• Disconnect the air duct from the throttle body. Most air ducts are attached with worm drive clamps or plastic snap clamps. Undo the clamps first. Then check for any sensors in the air duct. If you find sensors, disconnect the electrical connectors and label them. If you can’t remove the clamps, leave this job to the professionals.

• Disconnect the negative battery terminal to prevent accidental activation of the radiator fan.

• Remove the electronic throttle body from the intake manifold and place it on shop rags on your workbench.

Electronic throttle body cleaning — Step 2: Clean carbon buildup with throttle body spray cleaner and a rag

Wear rubber gloves for the following steps.

• Spray the cleaner onto a rag and wipe the liquid onto the throttle plate and throat. Let it soak.

WARNING: Do not spray throttle body cleaner directly onto the throttle plate. The cleaner can wick into the electronic portion of the throttle body and damage the circuit board and motor

• Wipe off the softened carbon buildup with a rag. Do not use any tools to scrape the carbon. That can damage the non-stick coating inside many throttle bodies.

Clean electronic throttle body— Step 3

• Install the new throttle body gasket.
• Reconnect all hoses that you removed from the throttle body
• Insert all bolts and torque to spec.
• Perform the electronic throttle body relearn for your engine.

​Clean a mechanical throttle body— Step 1

Mechanical throttle bodies don’t require removal for cleaning.
• Open the throttle plate manually and hold open while you spray the throttle body cleaner on the carbon buildup. Then spray the cleaner directly onto the throttle plate and shaft. Let it soak
• Wipe off the carbon buildup with a rag

Ford electronic throttle body cleaningSpray the rag and continue wetting and wiping the carbon buildup until it softens.

Ford electronic throttle body cleaning

Clean the edge of the throttle plate

©, 2015 Rick Muscoplat

Posted on by Rick Muscoplat

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