C 2500 Suburban 2WD V8-350 5.7L (1994)
Idle Speed: 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.
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Set parking brake and block drive wheels.
-
Connect a SCAN tool to the DLC connector with tool in Open Mode.
-
START engine and bring it to normal operating temperature.
NOTE Normal engine operating temperature range is 92° C to 104° C (196° F to 222° F)
-
Check for correct state of PRNDL position (R-D-L) 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 BY SYMPTOM / ROUGH, UNSTABLE OR INCORRECT IDLE.
MINIMUM IDLE AIR RATE CHECK
Minimum Idle Air Rate is not adjustable on this engine.
UNDER 8500 GVW
CONTROLLED IDLE SPEED
Transmission
Gear
Idle Speed
IAC Counts [1]
OPEN/CLOSED Loop [2]
Man.
N
650 +/- 25
5-30
CL
Auto
D
525 +/- 25
5-30
CL
[1] On manual transmission vehicles the scanner 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).
OVER 8500 GVW
CONTROLLED IDLE SPEED
Transmission
Gear
Idle Speed
IAC Counts [1]
OPEN/CLOSED Loop [2]
Man.
N
700 +/- 25
5-30
CL
Auto
D
550 +/- 25
5-30
CL
[1] On manual transmission vehicles the scanner 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).
