Stall Speed Test
WARNING:
Apply the service and parking brakes firmly while carrying out each stall test.
CAUTION:
Carry out the LINE PRESSURE TEST prior to carrying out the Stall Speed Test. If line pressure is low at stall, do not carry out the Stall Speed Test or further transmission damage will occur.
NOTE:
The stall test should only be carried out with the engine and transmission at normal operating temperatures.
The stall test checks the operation of the following items:
- Torque converter one-way clutch.
- Forward clutch.
- Low one-way clutch.
- Reverse clutch.
- Overdrive one-way clutch.
- Direct clutch.
- Engine driveability concerns.
- Connect a tachometer to the engine.
- After testing each of the following ranges, (D), 2, 1 and R, move the transmission range selector lever to N (NEUTRAL) and run the engine for about 15 seconds to allow the torque converter to cool before testing the next range.
- Press the accelerator pedal to floor (WOT) in each range. Record the rpm reached in each range. Stall speeds should be in the appropriate range.
CAUTION:
If the engine rpm recorded by the tachometer exceeds the maximum specified rpm, release the accelerator pedal immediately. Clutch or band slippage is indicated.
CAUTION:
Do not maintain wide-open throttle (WOT) in any gear range for more than 5 seconds or damage to the transmission may occur.
STALL SPEED CHART
| Series | Engine | Min. | Max. |
|---|---|---|---|
| Expedition/Navigator | 5.4L 2V | 2,297 | 2,725 |
| Navigator | 5.4L 4V | 2,274 | 2,736 |
If the stall speeds were too high, refer to Fig 1. If the stall speeds were too low, check engine tune-up. If the engine is OK, remove the torque converter and check the torque converter reactor one-way clutch for slippage.