TPS Adjustment

The Throttle Position Sensor (TPS) is part of the Fuel and Emission Control System. It has two major functions:
  1. To notify the ECU of the position of the throttle body. This allows the ECU to make adjustments to the air/fuel mix at different throttle positions.
  2. To cut the fuel off when you snap the throttle shut from being wide-open; this prevents backfiring.

Most common signs of a TPS that needs adjustment is a rough idle or a hesitation problem during acceleration. Bad backfiring could also be caused by the TPS, but this can also be due to installation of an aftermarket free-flowing exhaust.

NOTE: There are two types of Throttle Position Sensors.

The Series 4 sensor is NOT interchangeable with the Series 5. The Series 4 ('86-'88) TII and NA sensors are interchangeable, but the Series 5 ('89-'91) TII and NA sensors are NOT interchangeable. However, they are adjusted exactly the same.

Tools Required:

  1. TPS Tester (see Picture #1 below)
  2. Screw Driver
#1 TPS Tester
#2 Diagnostics Connector
#3 TPS Adjustment

Procedure:

    1. Bring car up to operating temperature.
    2. Plug in your TPS Tester :
    1. Remove the Intercooler (On a TII).
    2. Turn the car OFF and turn the ignition switch to the ON position. The TPS Tester should light up.
    3. If ONE lamp lights up, the TPS does not need adjusting.
    4. Otherwise (TWO or NO lights) adjust the TPS Adjustment Screw until ONE lamp lights up; approximately 1/4 turn past the 1st light (Picture #3):
      • Turn the screw counterclockwise if both lights are lit
      • Turn the screw clockwise if no lights illuminate

NOTE: DO NOT use excessive pressure on the screw; this will cause incorrect adjustment

Printable PDF Version

If you would like to purchase a TPS Tester please click here.

Banzai Racing Inc. & Associates are not responsible for any adverse effects arising from application of this procedure.

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