Computers and Control Systems: Adjustments
CONTROLLED IDLE SPEED CHECKNOTE Before performing this check:
- Verify no codes displayed
- Idle air control system has been checked
- Ignition timing is correct
PROCEDURE
- Set parking brake and block drive wheels.
- Connect a SCAN tool to the data link connector (DLC), 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 control module.
- If not within specifications, refer to DIAGNOSIS, TESTING AND INSPECTION PROCEDURES / TESTING PROCEDURES / DIAGNOSIS BY SYMPTOM / ROUGH, UNSTABLE OR INCORRECT IDLE.
MINIMUM IDLE AIR RATE CHECK
Minimum Idle Air Rate is not adjustable on this engine.
CONTROLLED IDLE SPEED
Body Gear Idle Speed IAC Counts [1] OPEN/CLOSED Loop [2]
M D 550 5-40 CL
L D 625 15-50 CL
[1] Add 2 counts for engines with less than 500 miles. Add 1 count for every 1000 ft. above sea level.
[2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop).