Stall Speed Test

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Carry out the Line Pressure Test prior to the Stall Speed Test. If line pressure is low, do not carry out the stall test or additional transmission damage will occur. Do not maintain Wide Open Throttle (WOT) in any gear range for more than 5 seconds.

NOTE: If the engine speed exceeds maximum specified rpm, release the accelerator pedal immediately.

NOTE: Only perform the stall speed test with the engine and transmission at normal operating temperatures.

To prevent damage to transmission and driveline components, the PCM will truncate engine torque output when a stall condition exists. Because of this torque truncation, the stall test cannot be used as a diagnostic test for determining the health of the transmission clutches.

The PCM monitors clutch performance and will set one or more DTCs when an undesired slip is detected.

The torque converter stator one-way clutch should hold at idle and during acceleration. A failed one-way clutch can be identified if all of the following conditions/symptoms exist:

Transmission fluid is clean and free of excessive contamination
Normal/expected vehicle performance at cruising speed
Poor engine idle quality. The engine may even stall
Very poor acceleration/Lack of power
Very low stall RPM: <1500 RPM. Perform test procedure below:

Apply the parking brake.
Connect the scan tool. Navigate to Datalogger: PCM
Monitor the PIDs: APP (%), RPM, LOAD (%) and GEAR_CMD
Start the engine.
Place the transmission in reverse.
Start datalogger recording.
With the brake pedal firmly applied, press the accelerator pedal to 100% for 2-3 seconds until engine RPM stabilizes. Release the accelerator pedal.
Place the transmission in neutral.
Press the accelerator pedal to maintain 1500 RPM for 10 seconds to allow the torque converter to cool. Release the accelerator pedal.
Place the transmission in drive.
With the brake pedal firmly applied, press the accelerator pedal to 100% for 2-3 seconds until engine RPM stabilizes. Release the accelerator pedal.
Place the transmission in neutral.
Press the accelerator pedal to maintain 1500 RPM for 10 seconds to allow the torque converter to cool. Release the accelerator pedal.
Turn the engine off.
Review the recording. A properly functioning stator one-way clutch should fall within the following parameters:
- APP = 100%
- RPM > 1500
- LOAD < 100%
- GEAR_CMD = Reverse or 1st Gear commanded