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 (M.U.T.-III sub assembly).

2. Chock both rear wheels.
3. Connect a tachometer.
4. Apply the parking and service brakes fully.
5. Start the engine.
6.
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.

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