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Stall Speed Test

This test checks operation of the following items:

WARNING: Apply the parking brake firmly while carrying out each stall test.
CAUTION: Always carry out the Line Pressure Test procedures 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 Speed Test should be carried out with the engine and transmission at normal operating temperatures.
  1. Connect tachometer to the engine.
    2. CAUTION: After testing each of the following ranges D5, D4, 3, 2, 1 and R, move the transmission range selector lever to N (NEUTRAL) and run the engine at 1,000 RPM for about 15 seconds to allow the torque converter to cool before testing the next range.
    CAUTION: Do not maintain wide open throttle (WOT) in any range for more than 5 seconds.
    CAUTION: If the engine RPM recorded by the tachometer exceeds maximum specified RPM, release the accelerator pedal immediately. Clutch or band slippage is indicated.
    NOTE: Prolonged use of this procedure may set DTC P0712, P1783. After carrying out Stall Speed Test, run OBD Test and clear DTCs from memory.
    Fig 1: Identifying Air Pressure Hole
    G04691136Courtesy of FORD MOTOR CO.
  2. Press accelerator pedal to floor (WOT) in each range. Record RPM reached in each range. Stall speeds should be as follows:
    STALL SPEED CHART

    Vehicle Engine RPM
    Lincoln LS 3.9L 2,268-2,677

    If stall speeds were too high, refer to the following STALL SPEED DIAGNOSIS CHART . If stall speeds were too low, first check the engine idle speed. If engine idle is OK, remove torque converter and check the torque converter one-way clutch for slippage.

    STALL SPEED DIAGNOSIS CHART

    Transmission Range Selector Lever Position Stall Speeds High Stall Speeds Low
    D5, D4 and 1 Overdrive one-way clutch, rear one-way clutch -
    D4, 2 and 1 Forward clutch, overdrive one-way clutch -
    D5 Forward clutch, overdrive one-way clutch -
    D5, D4, 3, 2, 1 and R General pressure concerns, forward clutch, overdrive one-way clutch Converter one-way clutch or engine driveability concerns
    R Only High/reverse, high clutch, low and reverse band/servo -
    2 Only Intermediate band/servo -
    1 Only Low/reverse band/servo -

    A no-drive or erratic shift condition may be due to inoperative bands and clutches. To diagnose these conditions, a series of checks can be made by substituting air pressure for fluid to determine the location of the damaged or obstructed component.

Follow the procedure to determine the location of the inoperative clutch or band by substituting air pressure into the various test plate passages.

NOTE: Use only dry, regulated 276 kPa (40 psi) maximum air pressure.
  1. Remove the main control valve body. Refer to MAIN CONTROL VALVE BODY .
  2. Install the transmission test plate and gasket.
    • Tighten to 10 Nm (89 lb-in).
    3. NOTE: Do not apply air to the test plate vent hole.
  3. Apply air to the appropriate clutch or servo port (refer to plate layout diagram). Refer to the AIR PRESSURE TEST DIAGNOSTIC CHART  for conditions, possible causes and actions.
  4. After the testing is completed, remove the air test plate and basket and proceed with any repairs that are needed.
  5. After the repairs are completed, install the main control valve body. Refer to MAIN CONTROL VALVE BODY .
AIR PRESSURE TEST DIAGNOSTIC CHART

Condition Possible Causes Actions
Dull thud heard or movement felt when air is applied and released Clutches, bands and fluid passages are OK. Concerns may not be in the transmission. Check the PCM, wiring harness and non-transmission related components.
No drive Clutches and bands inoperative. Disassemble the transmission, clean and inspect to locate area of concern.
Erratic shifts Clutches and bands inoperative due to incorrect pressures. Disassemble the transmission, clean and inspect to locate area of concern.
No dull thud heard Clutches, bands and fluid passages may be damaged or obstructed. Disassemble the transmission, clean and inspect to locate area of concern.
No movement felt Clutches, bands and fluid passages may be damaged or obstructed. Disassemble the transmission, clean and inspect to locate area of concern.
Hissing sound heard Clutch seals or check ball may be damaged or leaking. Disassemble the transmission, clean and inspect to locate area of concern.
Servos do not operate Seals and pistons may be damaged. Supply and release ports may be obstructed. Spring may be broken. Disassemble the transmission, clean and inspect to locate area of concern.
Multiple clutches are applied Fluid passages in the center support or the clutch cylinders may be obstructed. Disassemble the transmission, clean and inspect to locate area of concern. Check fluid passages in the center support for obstructions.
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