Idle Speed: Adjustments

Fig. 2 Curb idle speed adjust. V6-182:

NOTE: Curb idle speed (RPM) is controlled by the Electronic Engine Controls (EEC-IV) processor and the idle speed control air bypass valve assembly. The throttle plate stop screw is factory set and does not directly control idle speed. Adjustment to this seting should be performed only as part of a full EEC-IV diagnosis of irregular idle conditions or idle speeds. Failure to accurately set the throttle plate stop position to the procedure below could result in erroneous idle speed control.

IDLE SPEED ADJUSTMENT
- Place the transmission in "NEUTRAL" or "PARK", turn the A/C-HEAT selector switch to the "OFF" position, apply parking brake and block the wheels. If equipped with automatic brake release, disconnect the vacuum hose and plug it.
- Bring the engine to normal operating temperature, check for vacuum leaks down stream of the throttle plate.
- Check to ensure throttle lever stop pad is resting on the throttle plate stop screw and throttle linkage is not binding. Correct those conditions before proceeding.
- Perform an EEC-IV Quick Test and repair codes.
- Perform an "Idle Adaptive Learning Cycle" by disconnecting the negative (-) terminal of the battery for 5 minutes minimum, then reconnect battery.
- Start engine and check curb idle speed. If it is not controlled at 700 rpm continue with adjustment procedure.
- Unplug Spark Output (SPOUT) line and verify ignition timing is 10 degrees BTDC (+/- 2). Adjust timing if necessary.
- Remove PCV entry line at PCV valve and disconnect idle speed control air bypass power lead.
- Install orifice tool T86P-9600-A in PCV entry line (0.200 inch orifice diameter).
- Start engine, allow engine to idle in "DRIVE" with automatic transmission and in "NEUTRAL" with manual transmission.
- If the idle speed is not 710 rpm (+/- 20), adjust the throttle plate stop screw.

NOTE: If electric cooling fan comes on during idle set, unplug fan motor power leads or wait until fan switches off.

- After idle has been set, shut off engine. After waiting 3-5 minutes, repeat last two steps.
- Shut off engine, repeat "Idle Adaptive Learning Cycle".
- Remove orifice and reconnect PCV entry line to PCV valve.
- Reconnect SPOUT connector.
- Reconnect idle speed control air bypass valve power lead.
- Reconnect electric cooling fan.
- Start engine and let run 1-2 minutes.
- Recheck curb idle rpm, 700 rpm.
- On automatic transmissions check Throttle Valve (TV) pressure adjustment.