Idle Air Control (IAC) Valve: Installation

1991 Cadillac Seville STSSECTION Installation
  1. Inspect gasket or "O" ring for damage. Replace as necessary. Measure distance from IAC contact flange to tip of pintle. Distance should not exceed 1 1/8" (28 mm). If valve is extended too far, valve will be damaged during installation.
  2. To set IAC pintle length on new IAC, use finger pressure to slowly retract pintle. Lubricate new "O" ring with ATF and install new gasket. Install IAC valve on throttle body. Tighten IAC valve to specification. See TORQUE SPECIFICATIONS  table at end of article.
    CAUTION: DO NOT  extend or retract pintle if IAC valve has been in service, or damage to worm gear will result.
  3. Connect electrical lead to IAC valve, and install air cleaner. Start engine and hold engine speed at greater than 2000 RPM. Ground ALDL connector for 10 seconds then remove ground. Turn ignition off then restart engine. Check for proper idle operation.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.