Throttle Position Sensor (TPS) Adjustment
Symptoms: high idle, won't idle, dies when throttle is lifter when slowing down, surging idle speed
1. First bring the engine up to normal operating temperature.
2. Turn the engine off and unplug the Idle Air Control (IAC). This is located on the backside of the Throttle Body near the firewall. This device is a round cylinder approximately 5 inches long with a (2) bolt flange and 3 wire male / female plug connector (see pic).
3. Start engine and using a screwdriver adjust the base idle to 700 – 800 RPM using the screw on the throttle body (see pic)
4. Locate the Throttle Position Sensor (TPS) on the Throttle Body. This is also located on the backside of the Throttle Body near the firewall. This is a black plastic device with (2) screws that allows adjustment and (3) wire male / female connector (see pic above). Connect the voltmeter to the TPS and ground. The wire should be either black with a green stripe or green with a black stripe.
5. Using the small Phillips screwdriver adjust the TPS output voltage to approximately 1.0 volts. Most turbo tuners find that setting your voltage to around .90 - .95 volts works best. I set mine around .94 volts.
6. Turn off the engine.
7. With the engine off and the voltmeter still connected move the throttle linkage slowly from idle position to wide open and back to idle, look for a steady increase and then decrease in voltage without any voids or dead spots. Any voids or dead spots would indicate a faulty TPS. If you find a dead spot you need to replace the TPS.
8. Plug in the IAC.
9. Start the engine. The engine’s idle speed should settle in around 1000 RPM. If it settles higher than this, adjust the screw until idle is at 1000 RPM.
10. Go for a test drive and enjoy the smooth idle.