Idle Adjustment Precautions Mercury Sable II

Idle speed is controlled by PCM and idle speed control air by-pass valve. If control system is operating properly, engine idle RPM is fixed and cannot be changed by standard adjustments. A scan tool must be used on these systems because control strategy and idle speed specification are controlled by PCM.

Before adjusting idle speed, complete a thorough basic inspection and self-tests (KOEO, KOER and continuous memory) to confirm correct operation of sub-systems contributing to idle speed control. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section.

Ensure throttle bore and both sides of throttle plate(s) are clean, throttle plate does not stick in bore, and/or linkage is not limiting throttle plate operation. Throttle lever must rest on throttle stop screw. When idle speed control device (air-by pass solenoid or DC motor) is disconnected to set minimum air rate, engine may stall. This is acceptable only if throttle plate and linkage are not stuck.

Throttle bodies use sludge resistant throttle plate designs and must not be cleaned because of protective coating on lip of throttle plate(s). For location of identification label on 3.0L, 3.2L and 3.8L, see illustration. see scheme 2& 3.

Ensure all accessories are turned off before checking and adjusting idle speed. Ensure cooling system is filled to correct level. Ensure vacuum leaks do not exist and unmetered air does not enter throttle chamber on mass airflow design systems. If vehicle is equipped with electric cooling fan, check and adjust idle speed when fan is off.

Scheme 3

Scheme 4

IDLE SPEED SPECIFICATIONS

Scheme 5

1. Connect Super Star II scan tool to diagnostic connector. Enter KOER self-test. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section. After Code 11 or 111 has been displayed, unlatch and then, within 4 seconds, latch STI button. A single pulse code indicates that entry mode has been successfully entered.
2. Observe scan tool readout. If a constant tone, solid light or STO LO is displayed, base idle speed is within range and no adjustment is necessary. Unlatch STI button to exit self-test.
3. If a beeping tone, flashing light or STO LO at 8 Hz is displayed, Throttle Position (TP) sensor is out of range and should be checked. See «THROTTLE POSITION (TP) SENSOR»(ref-22781-S10113124462001010300000). Repeat KOER self-test.
4. If a beeping tone, flashing light or STO LO at 4 Hz is displayed, base idle speed is too high. Go to step 6). If a beeping tone, flashing light or STO LO at one Hz is displayed, base idle speed is too low. Go to next step.
5. DO NOT clean throttle bore. Check throttle plate for presence of throttle plate orifice plug. (Scheme 5) If plug does not exist, turn idle adjusting screw clockwise only to adjust idle speed until conditions in step 2) are obtained. If plug from previous service exists, remove it and turn screw to obtain conditions in step 2). After adjustment is complete, ensure screw contacts lever pad.
6. Turn engine off. Using tape, block off orifice in throttle plate. (Scheme 5) If orifice is already plugged, go to step 9).
7. On mass airflow engines, reconnect air cleaner hose. On all models, restart engine, and check idle speed. If engine stalls, crack throttle plate open using throttle plate stop screw. (Scheme 6) If idle speed is still too high as described in step 4), go to next step. If idle speed drops to specification or less as described in steps 2) and 4), go to step 9).
8. Perform KOEO self-test. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section. Check for fault codes, especially TP sensor fault code. If fault codes are present, repair as necessary. If TP sensor fault code is present, check for proper TP sensor output. See «THROTTLE POSITION (TP) SENSOR»(ref-22781-S10113124462001010300000). Ensure adjustment screw contacts lever pad. If no fault codes are present, see appropriate TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
9. Turn ignition off. Remove air cleaner hose, and remove tape covering throttle plate orifice. Select correct color plug for orifice. Plugs are available in Throttle Plate Plug Kit (FOPZ-9F652-A).
10. Reconnect air cleaner hose, and start engine. Recheck idle speed. If idle speed is not within specification, turn adjusting screw clockwise until condition in step 2) is obtained. After adjustment, screw must contact lever pad.
11. Perform KOEO self-test to ensure TP sensor fault code is not present. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section. Move throttle plate to ensure it is not stuck in bore and linkage is not keeping throttle from closing. On models with automatic overdrive transmissions, check throttle valve pressure adjustment.

Scheme 6

Note. If electric cooling fan comes on, discontinue testing until fan goes off.