Adjusting the TPS
Ken Mosher
To adjust the Throttle Position Sensor to recommended settings of between 0.40-0.46 volts at idle and between 4.5 and 4.8 volts at Wide Open Throttle (WOT). This procedure should be performed after the minimum idle air settings are already made (via the IAC reset procedure).
Equipment Needed
The following tools are needed:
  • Flat bladed screwdriver
  • Scan tool (alternatively, a digital voltmeter)
  1. Hook up your scan tool where you can see the readings clearly from under the hood (alternatively, back probe the TPS blue wire with the positive lead of the meter and ground the meter's negative lead to the chassis or battery)

  2. Turn the key ON and leave the engine OFF

  3. Loosen the two screws on the side of the sensor (passenger side of the throttle body) enough to allow you to move the sensor in the "moon shaped" grooves.
  4. Grab the "nose" of the sensor (where the wires plug in) and pull the sensor as far forward as possible and snug the screws enough that it holds the sensor in place (but can still be moved if nudged)

  5. Check the idle reading and tap the nose of the sensor up or down until you get an idle reading of between 0.40 and 0.46 volts. Anything above about 0.5 volts will not be seen as "idle" by the ECM and can cause driveability problems.

  6. Snug the screws down tight enough that the sensor doesn't move and have someone floor the throttle (make sure that the floor mat is out of the car...)

  7. Check the reading and adjust until the sensor reads between 4.55 volts and 4.85 volts. The intent is to make sure that the reading is high enough that the ECM reads full WOT. The actual number doesn't really matter as long as it is with the range.

  8. Recheck the idle reading to make sure that it hasn't changed. This can be a bit of a balancing act and require some very small adjustments and several iterations before both the high and low settings are where you want them to be.

Note: Occaisonally a TPS will need the moon shaped grooves honed out a bit with a rat tail file to get enough adjustment, but normally the trick of moving the sensor as far foward as possible gives enough adjustment. Also, be very careful around the little roll pin that rests on the throttle lever, since it can bend or break.

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