C 1500 Truck 2WD V8-350 5.7L (1989)
Idle Speed: Adjustments
Minimum Air Rate - Fuel Injection Only
CONTROLLED IDLE SPEED CHECK
1.
Set parking brake and block drive wheels.
2.
Connect a SCAN tool to the assembly line data link (ALDL) connect with tool in Open Mode.
3.
START engine and bring it to normal operating temperature.
4.
Check for correct state of PARK/NEUTRAL switch on SCAN tool.
5.
Check specifications chart for controlled idle speed and IAC valve pintle position (counts).
6.
If within specifications, the idle speed is being correctly controlled by the ECM.
7.
If not within specifications, perform MINIMUM IDLE AIR RATE CHECK.
MINIMUM IDLE AIR RATE CHECK
1.
Check controlled idle speed and perform idle air control check first.
2.
Set parking brake and block drive wheels.
3.
START engine and bring it to normal operating temperatures 185-212 degrees Fahrenheit (85-100 degrees Celsius). Turn engine OFF.
4.
Remove air cleaner, adapter and gaskets. Check that the throttle lever is not being bound by the throttle, throttle valve or cruise control cables.
Figure 1 Terminal Arrangement In Connector
5.
With IAC valve connected, ground the diagnostic terminal (ALDL).
6.
Turn ON ignition, DO NOT START engine. Wait at least 10 seconds (this will allow the IAC pintle to extend and seat in the throttle body.).
7.
With ignition ON, engine stopped, test terminal still grounded, disconnect IAC valve electrical connector. (This disables the IAC valve in the
seated position). Remove the ground from the diagnostic terminal.
8.
Connect a SCAN tool to the ALDL connector and place in open mode. If a tool is not available connect a tachometer to the engine.
9.
START engine. With transmission in NEUTRAL, allow engine rpm to stabilize.
