Things You'll Need
The throttle body injector (TBI) of a vehicle helps control the throttle and maintain the minimum revolutions per minute, or rpm. General Motors vehicles use the TBI in the same manner as most automobiles. To adjust the throttle position sensor (TPS) of the TBI, you must remove the TBI and alter its makeup slightly. Turning the TPS down may help improve the way your vehicle runs, but if you turn it too low, your vehicle may not start. Adjusting the TBI requires precise movements and should only be attempted by someone familiar with GM engines.
Turn your car off by turning the key counterclockwise. Remove the key from the ignition.
Open the hood of your car and locate the TBI. The location of the TBI will vary, depending on your GM vehicle. Consult the engine diagram that came with your vehicle for extra guidance.
Remove the TBI using an Allen wrench. Unscrew the TBI's bolt with the wrench and pull the TBI from the car. Set it on a flat surface.
Test the voltage of your TBI using a multimeter. Push the multimeter pin into the TPS screw and check the voltage. Note the reading on the multimeter.
Adjust the TBI. Turn the throttle down by tightening the TBI's screws. Tighten the screw by turning it clockwise.
Test the voltage of your TBI using a multimeter. Push the multimeter pin into the TPS screw and check the voltage. The reading should be the same as the previous reading.
Replace the TBI by placing it back in the engine. Close the hood of the car. Start the engine to test the TBI. Take note of the rpm when the car is in park.
Adjusting TBI can be difficult if you are unfamiliar with automobile engines.