Computers and Control Systems: Adjustments

CONTROLLED IDLE SPEED CHECK:

NOTE: Before performing this check, there should be no codes displayed, idle air control system has been checked and the ignition timing is correct.

- Set parking brake and block drive wheels.
- Connect a SCAN tool to the assembly line data link (ALDL) connect with tool in Open Mode.
- START engine and bring it to normal operating temperature.
- Check for correct state of PARK/NEUTRAL switch on SCAN tool.
- Check specifications chart for controlled idle speed and IAC valve pintle position (counts).
- If within specifications, the idle speed is being correctly controlled by the ECM.
- If not within specifications, refer to DIAGNOSIS BY SYMPTOM/DIAGNOSIS AND TESTING PROCEDURES/ROUGH, UNSTABLE OR INCORRECT IDLE.

MINIMUM IDLE AIR RATE CHECK
Minimum Idle Air Rate is not adjustable on this engine.

CONTROLLED IDLE SPEED

Transmission Gear Idle Speed IAC Counts [1] OPEN/CLOSED Loop [2]

Man. N 650 +/- 25 5-30 CL

Auto D 550 +/- 25 5-30 CL

[1] On manual transmission vehicles the TECH 1 will display RDL in Neutral. Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level.

[2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop).