K 3500 Truck 4WD V8-454 7.4L VIN N TBI (1995)
Idle Speed: Adjustments
Minimum Idle Speed Adjustment
1. Check controlled idle speed and perform idle speed control system check first.
2. Set parking brake and block drive wheels.
3. Start engine and bring it to normal operating temperature 85°C-100°C (185°F-212°F). Turn engine "OFF."
4. Remove air cleaner, adapter and gaskets. Check that the throttle lever is not being bound by the throttle or cruise control cables.
5. With IAC valve connected, Connect Tech 1 and command IAC counts to 0.
6. With ignition "ON," engine stopped, disconnect IAC valve electrical connector. (This disables IAC valve in seated position.) Care should be taken
to pull the connector straight out so that the moment of electrical disconnect is the same for all the pins. Otherwise the pintle may move as the
connector is removed.
7. Start engine. With transmission in neutral, allow engine rpm to stabilize. Make sure that the ISC actuator is not contacting the throttle lever. If so
refer to "IAC Actuator System Check."
8. Check rpm against specifications. Disregard IAC counts on Tech 1 scan tool with the IAC disconnected. If the engine has less than 500 miles or is
checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than values above.
9. If the minimum idle speed is within specifications, no further check is required.
10. If the minimum idle speed is not within specifications, perform the following procedures:
Idle Stop Screw
11. If present, remove stop screw plug by piercing it with an awl, then applying leverage. The screw is covered to discourage unauthorized
adjustments.
12. With engine at normal operating temperature 85°C-100°C (185°F-212°F), adjust stop screw to obtain nominal rpm per specifications with seated
IAC valve.
13. Turn ignition "OFF," and reconnect IAC valve electrical connector.
14. Disconnect Tech 1 scan tool or tachometer.
15. Use silicon sealant or equivalent to cover stop screw hole.
16. Install air cleaner and adapter.
17. Reset IAC valve. Refer to "Idle Air Control (IAC) System Check."
