Minimum Idle Speed Adjustment (7.4L)
- Check controlled idle speed and perform IAC system check first. Refer to CONTROLLED IDLE SPEED CHECK heading above. Set parking brake and block drive wheels. Start engine and operate to normal operating temperature, about 185-212°F (85-100°C). Turn engine off.
- Remove air cleaner, adapter and gaskets. Ensure that throttle lever is not binding TV or cruise control cables. Using a jumper, ground Diagnostic Link Connector (DLC). Turn ignition on (engine off). Wait for at least 10 seconds (this allows IAC pintle to extend and seat in throttle body).
- Disconnect IAC harness connector. Remove jumper from DLC. Connect scan tester to DLC. Place scan tester in "Open Mode". Place transmission in Neutral. Start engine. Allow engine RPM to stabilize. Check engine RPM. See «MINIMUM IDLE SPEED»(ref-19725-S05606255282001010200000) . Disregard IAC count on scan tester with IAC disconnected.
- If idle speed is not as specified, remove stop screw plug by using an awl. With engine at normal operating temperature, adjust stop screw to obtain nominal RPM with seated IAC valve. Turn ignition off. Reconnect IAC harness connector. Disconnect scan tester. Reseal stop screw hole and reinstall air cleaner assembly.
- Reset IAC valve. To reset IAC valve, turn ignition on (engine off) for 5 seconds. Turn ignition off for 10 seconds. Start engine and check for proper idle operation. Repeat procedure if proper idle operation is not obtained.
| Application | RPM |
|---|
| 7.4L |
| Auto. Trans. (2) | 600-650 |
| Man. Trans. (3) | 675-725 |
| (1) Idle speed with seated IAC is lower than specified, if engine has less than 500 miles or when checked at altitudes above 1500 feet. (2) Automatic transmission in Drive. (3) Manual transmission in Neutral. |
| (1) | Idle speed with seated IAC is lower than specified, if engine has less than 500 miles or when checked at altitudes above 1500 feet. |
| (2) | Automatic transmission in Drive. |
| (3) | Manual transmission in Neutral. |
