Minimum Idle (Eldorado & Seville) Buick Roadmaster VIII

1. Warm engine to normal operating temperature. Turn A/C and all accessories off. Enter diagnostics, and select Powertrain Control Module (PCM) override PS03, Idle Speed Control (ISC) motor. See appropriate G - TESTS W/ CODES article in this section.
2. Press COOLER button on Climate Control Panel (CCP). This action disengages A/C compressor, commands EGR off and turns off alternator. CCP will display 50 to 00. ISC motor will slowly move to a fully retracted position (in about 20 seconds).
3. Ensure throttle lever rests on minimum idle speed screw. Adjust plunger as necessary, using ISC Adjusting Wrench (J-38457). Check throttle lever for binding. Readjust or repair cables causing throttle to bind.
4. Check minimum idle speed displayed on Driver Information Center (DIC). If minimum idle is not as specified, go to step 5) or 6). See «MINIMUM IDLE SPEED - 4.9L»(ref-19418-S18133547002001010200000) table. If minimum idle speed is okay, check TP sensor adjustment. See THROTTLE POSITION (TP) SENSOR.
5. If engine stalls at minimum air (ISC fully retracted), check throttle blades for deposits which might restrict airflow. Clean throttle bores. Clean behind and around throttle plates. Check minimum idle speed displayed on DIC. Use average RPM reading to set minimum idle speed. See «MINIMUM IDLE SPEED - 4.9L»(ref-19418-S18133547002001010200000) table. Check for vacuum leaks.
6. If engine RPM is too high, check for vacuum leaks at throttle body, intake manifold, vacuum fittings, etc. Repair vacuum leaks. Adjust minimum idle screw to obtain specified RPM. See the «MINIMUM IDLE SPEED - 4.9L»(ref-19418-S18133547002001010200000) table. Check TP sensor adjustment. See THROTTLE POSITION (TP) SENSOR. Start engine, and check for proper idle operation.

MINIMUM IDLE SPEED - 4.9L