Throttle Position Sensor: Adjustments

Before adjusting the idle speed or the Throttle Position Sensor, be sure:
^ Engine coolant has reached operating temperature 185-195~F (85-95~C).
^ Lights, cooling fan, and all electrical accessories are OFF.
^ Transaxle is in PARK or NEUTRAL
^ Steering wheel is in a straight ahead position.

1. Slacken the accelerator cable.

Tachometer Connection:

2. Connect a tachometer.

Verifying TPS Output To The Control Unit:

3. Connect a digital voltmeter to the MPI Control Unit as illustrated, without disconnecting the harness connectors.
4. Turn ON the ignition switch (without starting the engine) for more than 15 seconds.
5. Turn OFF the ignition switch.

ISC Servo Connector:

6. Disconnect the connectors of the Idle Speed Control Servo and lock the ISC plunger at the initial position.
7. Back out the Fixed SAS.
8. Start the engine and let it idle.
9. Verify that the engine is running at the BASIC idle speed.
Refer to SPECIFICATIONS/MECHANICAL.

Idle Speed Adjustment Screws:

10. If the engine speed does not meet specifications, use a hexagon socket and driver to adjust the Idle Speed Adjusting Screw.
11. Turn in the Fixed SAS until the engine speed rises. Then back out the Fixed SAS until the Touch Point is found.
NOTE: The Touch Point is the where the engine speed does not fall any longer.
12. Back out the Fixed SAS an additional half turn from the Touch Point.
13. Stop the engine.
14. Turn ON the ignition switch (without starting the engine), and verify output voltage from the Throttle Position Sensor (TPS) is between 0.48-0.52 volts.

TPS Adjustment:

15. If the voltage is not within specification, adjust the TPS by loosening the TPS mounting screws and rotating the TPS. After adjustment tighten the screws firmly.
NOTE: Clock-wise rotation of the TPS will increase the output voltage.
16. Set the ignition switch to the OFF position.
17. Adjust the freeplay of the accelerator cable.
18. Reconnect the connectors of the Idle Speed Control Servo.
19. Remove the voltmeter.
20. Start the engine and verify that the idle rpm has returned to the CURB Idle Speed.
Refer to SPECIFICATIONS/MECHANICAL.