Throttle Body Assembly


Throttle body inspection and service procedures vary widely depending on the year and make of the vehicle. However, some components such as the TP (throttle position) sensor are found on nearly all throttle bodies. Since throttle bodies have some common components, inspection procedures often involve checking common components.

  • Check for smooth movement of the throttle linkage from idle position to the wide-open position.
  • Check the throttle linkage and cable for wear and looseness.
  • Check the vacuum at each vacuum port on the throttle body while the engine is idling and while it is running at a higher speed.
  • Apply vacuum to the throttle opener. Then, disconnect the TP sensor connector, and test the TP sensor with an ohmmeter connected across the appropriate terminals.
  • Loosen the two TP sensor mounting screws and rotate the TP sensor as required to obtain the specified ohmmeter readings. Then retighten the mounting screws. If the TP sensor cannot be adjusted to obtain the proper ohmmeter readings, replace the TP sensor.
Loosen the TP sensor's mounting screws to adjust the sensor. Reprinted with permission.
  • Operate the engine until it reaches normal operating temperature, and check the idle speed on a tachometer. The idle speed should be 700 to 800 rpm.
  • Disconnect and plug the vacuum hose from the throttle opener. Maintain 2,500 engine rpm.
  • Release the throttle valve and observe the tachometer reading. When the throttle linkage strikes the throttle opener stem, the engine speed should be between 1,300 and 1,500 rpm. Adjust the throttle opener, as necessary, and reconnect the throttle opener vacuum hose.