The Ins and Outs of Throttle Bodies

What is a Throttle Body?

A throttle body is the part of the air intake system that controls the amount of air flowing into the engine, in response to the driver accelerator pedal input. What this means is when the driver pushes the gas pedal, the throttle body opens to allow air to get to the engine. So basically, the more gas you give your car, the more air the throttle body allows to get to the engine.

What is the Difference Between a Mechanical vs. Electric Throttle Body?

There are two different types of throttle bodies that your car can have, mechanical and electric, also know as “drive by wire”. The type of throttle body you have depends on how the automaker made the car. The way a mechanical throttle body works is that the accelerator pedal motion communicates through the throttle cable, which activates the throttle linkages then, moves the throttle plate to allow air into the engine. “Drive by wire” uses an electric motor which controls the throttle linkages, and the accelerator pedal connects to a senor, not the throttle body. The sensor sends the pedal position to the Engine Control Unit (ECU), which determines the throttle opening based on the accelerator position and other engine sensors.

Mechanical Throttle Body

“Drive By Wire” or Electric Throttle Body

Why is it Important to Clean Your Throttle Body?

Over the years of driving your car, gasoline gum build up, dirt and other foreign matter attaches themselves to the throttle body fuel injection (TBI) unit walls and passages. The build up affects the unit’s operation and fuel quality entering the engine. In severe cases, the throttle plate many start to have difficulty opening and closing, and may even get stuck. If the throttle plate gets stuck, the car won’t start so it is very important to clean your throttle body every once in a while.

How to Clean Your Throttle Body?

1. Pop the hood, relieve the fuel system pressure, and disconnect the black negative cable from the battery terminal. Refer to the car’s manual to properly relieve the fuel system pressure on your particular vehicle and locate components if necessary. If you do not have your car’s manual, you can purchase one at most auto parts stores or find one for free at a public library.

2. Take off the air cleaner assembly.

3. Disconnect the cable of cables attached to the throttle lever.

4. Unplug the electrical connectors from sensors, valves, idle control motor unit, and disconnect vacuum hoses attached to the throttle body (if necessary) make a note of the connector you unplug for easier installation.

5. Disconnect the inlet and return fuel lines from the throttle body.

6. Remove the bolts or nuts attaching the TBI unit to the intake manifold using a wrench or ratchet and socket.

7. Lift the throttle body off the intake manifold and remove plastic, rubber, and other electrical parts still attached to the unit. Keep part organized for easier reassembling.

8. Immerse the TBI in carburetor cleaner following the product manufacturer instructions.

9. Replace gaskets, seals, and worn parts as necessary and reassemble the throttle body. If you need the replacement parts, bring old ones to an auto parts store for assistance.

10. Clean the intake manifold mating surface from old gasket material thoroughly, using a scraper, lacquer thinner and a clean rag.

11. Install the throttle body unit on to the intake manifold using a new base plate gasket and tighten the mounting bolts in sequence to the specifications listed in the car’s manual.

12. Connect the inlet and return fuel lines; plug electrical connectors and install vacuum hoses, throttle lever cables, air cleaner assembly, and connect the black negative cable to the battery terminal.