The throttle position sensor (TPS) in your Pontiac Sunfire provides a variable-resistance signal to the onboard computer. Along with the manifold absolute pressure sensor (MAP) signal, the engine can calculate engine load. The computer adjusts ignition timing and fuel injector pulse width requirements based on these signals to provide smooth operation across the entire rpm range and under all driving conditions. The sensor in the Sunfire is a non-adjustable type and is easy to remove and replace.
Disconnect the negative battery cable using an 8 mm wrench. Lay the cable out of the way to prevent arcing that could happen if it makes contact with the battery terminal. Loosen the clamps that attach the flexible rubber duct to the air filter housing and the throttle body, using a flat-blade screwdriver. Twist and pull the duct until it slides off the air filter housing and throttle body. Remove the air duct from the engine compartment.
Unplug the electrical connector from the TPS, located on the side of the throttle body, opposite of the throttle cable. Remove the two T-15 Torx screws from the sensor, and pull the sensor from the throttle body.
Line up the tabs in the new sensor with the flat tang on the end of the throttle shaft and press the sensor into place on the throttle body. Rotate the sensor counterclockwise to line up the screw holes before installing the two Torx screws.
Connect the electrical connector to the new sensor. Reinstall the air duct and tighten the clamps securely with a screwdriver. Clear codes stored in the onboard computer, using a scan tool, and test-drive the car to verify that the repair fixed the problem.
