Idle Rpm Test
NOTE:
Engine idle set RPM should be tested and recorded when vehicle is first brought into shop for testing. This will assist in diagnosing complaints of engine stalling, creeping, and hard shifting on vehicles equipped with automatic transmissions. Curb idle speed on 2.5L and 4.0L are controlled by electronic control unit and are not adjustable.
- Using a tachometer, connect Red tachometer lead to negative terminal of coil and Black lead to ground.
- Turn selector switch to appropriate cylinder position of engine being tested. Start engine and warm to operating temperature.
- Turn tachometer RPM switch to 1000 RPM position.
- With engine at operating temperature, momentarily open throttle and release to ensure there is no binding in linkage and throttle lever is fully against its stop.
- Note engine RPM. See CURB IDLE SPEED table. If engine RPM is not within specification, see appropriate TESTS W/CODES article for 2.5L and 4.0L and see ADJUSTMENTS article for 4.2L and 5.9L.
CURB IDLE SPEED
| Application | Idle RPM | |
|---|---|---|
| 2.5L, 4.0L & 4.2L | ||
| 50 States | 680 | |
| High Altitude | 700 | |
| 5.9L | 600 | |