Torque Converter Stall Test

TORQUE CONVERTER STALL TEST





This test measures the maximum engine speed when the selector lever is in the D or R position and the torque converter stalls. This tests the operation of the torque converter, stator and one-way clutch operation, as well as the holding performance of the clutches and brakes in the transaxle.

WARNING: Do not let anyone stand in front of or behind the vehicle while this test is performed.

1. Check the transmission fluid level and temperature. Check the engine coolant temperature.
^ Transmission fluid level: At the HOT mark on the dipstick
^ Transmission fluid temperature: 70 - 80°C (158 - 176°F)
^ Engine coolant temperature: 80 - 100°C (176 - 212°F)

NOTE: Measure transmission fluid temperature with scan tool MB991958 (MUT-III) sub assembly).

2. Chock both rear wheels.
3. Connect a tachometer.
4. Apply the parking and service brakes fully.
5. Start the engine.





CAUTION:
^ The throttle should not be fully open for more than five seconds.
^ If you repeat the stall test when the transmission fluid temperature is greater than 80°C (176°F), move the selector lever to the N position and let the engine run at approximately 1,000 r/min for at least one minute. Wait until the transmission fluid temperature returns to 80°C (176°F) or less.

6. Move the selector lever to the D position. Fully depress the accelerator pedal and read the maximum engine speed.
Standard value: Stall speed: 2,500 - 3,000 r/min <4A/T>
Standard value: Stall speed: 2,200 - 2,700 r/min <5A/T>
7. Move the selector lever to the R position. Fully depress the accelerator pedal and read the maximum engine speed.
Standard value: Stall speed: 2,500 - 3,000 r/min <4A/T>
Standard value: Stall speed: 2,200 - 2,700 r/min <5A/T>

TORQUE CONVERTER STALL TEST JUDGMENT RESULTS
1. Stall speed is too high in both "D" and "R" range.
^ Malfunction of the torque converter (Slippage on the splines of the torque converter and the input shaft)
^ Low line pressure
^ Low-reverse brake slippage and malfunction of the one-way clutch
2. Stall speed is too high in "D" range only
^ Underdrive clutch slippage
3. Stall speed is too high in "R" range only
^ Reverse clutch slippage
4. Stall speed is too low in both "D" and "R" ranges
^ Malfunction of the torque converter (Slippage of the one way clutch)
^ Insufficient engine output