What voltage should the Throttle Position Sensor (TPS) be set to?

The sheet says to set the TPS anywhere from .96 to .98 volts by loosening the mounting screws and lightly rotating the TPS. If the desired range can't be obtained, the mounting holes can be drilled slightly larger.

Which TPS wires should be probed when setting TPS voltage?

Generally the BLACK and GREEN wires, or the GRAY/RED and GRAY/WHITE wires, depending on your vehicle.

What do I do if the engine stalls when the IAC solenoid is unplugged?

Turn the throttle-stop screw in one full turn and restart. Repeat as necessary until the engine will idle with the IAC solenoid unplugged.

How do I reset the computer to factory defaults after adjusting idle?

Stop the engine and disconnect the negative battery terminal cable for 15-20 minutes. Tapping the brakes or turning the headlights on and off a few times helps purge remaining electrical current, resetting the computer to factory defaults.

What should I check if the idle problem persists after the procedure?

Inspect for mass air meter problems and possible vacuum leaks.

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Ford Racing Idle Setting Procedure Instruction Sheet IS-1850-0156 - TPS & IAC

Ford Racing idle setting procedure instruction sheet IS-1850-0156 IAC TPS throttle stop

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Ford Racing idle-setting instruction sheet: disconnect IAC solenoid, set idle via throttle stop, and set TPS to .96-.98 volts in sequence.

AI caption March 2012 · Photo 1247 of 1799

This is a one-page Ford Racing Performance Parts instruction sheet (document number IS-1850-0156) describing the official idle setting procedure for Ford EFI engines. It presents nine sequential steps that must be performed in order: warm the engine to operating temperature, unplug the Idle Air Control (IAC) solenoid (turning the throttle-stop screw in as needed to keep the engine idling), set base idle with the throttle stop, and adjust the Throttle Position Sensor (TPS) to read between 0.96 and 0.98 volts by loosening and rotating the sensor (drilling the mounting holes slightly larger if needed). It notes the TPS wires to probe are generally BLACK and GREEN, or GRAY/RED and GRAY/WHITE, depending on the vehicle. The procedure then calls for disconnecting the negative battery cable for 15-20 minutes (tapping the brakes or cycling headlights to purge residual current) to reset the computer to factory defaults, reconnecting the IAC solenoid and battery, and restarting the engine. If idle problems persist, the sheet advises checking for mass air meter problems and vacuum leaks. Contact information for the Ford Racing Techline (800-FORD788) and Helm Publications (1-800-782-4356) for factory shop manuals is provided.

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Frequently asked questions

What voltage should the Throttle Position Sensor (TPS) be set to?: The sheet says to set the TPS anywhere from .96 to .98 volts by loosening the mounting screws and lightly rotating the TPS. If the desired range can't be obtained, the mounting holes can be drilled slightly larger.
Which TPS wires should be probed when setting TPS voltage?: Generally the BLACK and GREEN wires, or the GRAY/RED and GRAY/WHITE wires, depending on your vehicle.
What do I do if the engine stalls when the IAC solenoid is unplugged?: Turn the throttle-stop screw in one full turn and restart. Repeat as necessary until the engine will idle with the IAC solenoid unplugged.
How do I reset the computer to factory defaults after adjusting idle?: Stop the engine and disconnect the negative battery terminal cable for 15-20 minutes. Tapping the brakes or turning the headlights on and off a few times helps purge remaining electrical current, resetting the computer to factory defaults.
What should I check if the idle problem persists after the procedure?: Inspect for mass air meter problems and possible vacuum leaks.