Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Idle Air Control (IAC) Valve: Installation
1991 Cadillac Seville STSSECTION Installation
- Check the extended distance of new IAC before installing. Damage will occur if measurement is incorrect. Distance must not exceed 1 1/8" (28 mm). Measurement should be taken from valve housing flange to end of cone. DO NOT extend or retract pintle on IAC valve that has been in service, or damage to internal worm drive may occur.
- To retract pintle on new IAC, slowly exert finger pressure on valve. Install new "O" ring or gasket on valve. Coat "O" ring with oil. Install IAC valve. Tighten IAC valve to specifications. See TORQUE SPECIFICATIONS table at end of article. Install electrical connector.
- To reset IAC valve on 2.3L (VIN A), connect "Scan" tester. Start engine and hold engine speed at about 2000 RPM. Using "Scan" tester, select Field Service mode for 10 seconds then exit from Field Service mode. Turn engine off, then restart engine and check for proper idle operation.
- On 2.3L (VIN D), turn ignition on, but do not start engine. Ground ALDL connector for 5 seconds. Remove ground from ALDL connector. Turn ignition on for 10 seconds. Start engine and check for proper idle operation.
- On 3.1L & 3.4L, turn ignition on for 5 seconds, then turn ignition off for 10 seconds. Start engine and check for proper idle operation.
- On 3.3L, turn ignition on, but do not start engine. Ground ALDL connector for 5 seconds. Remove ground from ALDL connector. Start engine and check for proper idle operation.
- On 5.7L (VIN 8), depress accelerator slightly. Start and run engine for 5 seconds. Turn ignition off for 10 seconds. Restart engine and check for proper idle operation.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.