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.
- Bring the engine to normal operating temperature, check for vacuum leaks down stream of the throttle plate.
- Unplug Spark Output (SPOUT) line and verify ignition timing is 10 degrees BTDC (+/- 2). Adjust timing if necessary.
- Shut off engine and disconnect air bypass valve assembly connector.
- Remove PCV entry line at PCV valve and 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.

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

- If the idle speed is not 625 rpm (+/- 30), adjust the throttle plate stop screw.
- After idle has been set, shut off engine.
- Restart vehicle and confirm idle speed is 625 rpm (+/- 30) after 3-5 minutes.
- If speed is not to within specification repeat adjustment procedure.
- Shut off engine.
- Remove orifice and reconnect PCV entry line.
- Reconnect SPOUT line.
- Reconnect air bypass valve assembly connector.
- Reconnect electric cooling fan.
- Verify throttle plate is not stuck in the bore and that the throttle plate stop screw is setting on the rest pad with the throttle closed. Correct any condition that will not allow the throttle to closed to the stop set position.
- Restart engine. After 3-5 minutes of running engine speed should be at idle speed specification.