Lincoln Corsair: Automatic Transmission - 8-Speed Automatic Transmission – 8F35/8F40 / Diagnosis and Testing - Special Testing Procedures

Principles of Operation

Line Pressure Test

This test verifies the line pressure is within specification.

1. Remove the air cleaner.
   REFER to: Air Cleaner (303-12B Intake Air Distribution and Filtering - 2.3L EcoBoost (199kW/270PS), Removal and Installation).

1. Connect the transmission fluid pressure gauge (307-004) to the line pressure tap.
   

1. Install the air cleaner.
   REFER to: Air Cleaner (303-12B Intake Air Distribution and Filtering - 2.3L EcoBoost (199kW/270PS), Removal and Installation).

1. NOTE: Some transmission calibrations may maximize line pressure (300 PSI (2068 kPa)) during warm-up. Commanding LINEDSD# may have minimal effect.

   Start the engine, allow TFT to reach normal operating temperature (if possible) and check the line pressure.
   

1. Using a diagnostic scan tool, monitor and compare the PID LINEDSD# to actual measured pressure. Actual measured pressure should be within 10 PSI (69 kPa) of PID LINEDSD#. Raise engine RPM to 2000 RPM and verify LPC operation by monitoring LINE pressure while commanding LINEDSD# up and down.
   

1. If the line pressure is not within specification, see the Line Pressure Diagnosis Chart for possible source.
   

1. Remove the air cleaner.
   REFER to: Air Cleaner (303-12B Intake Air Distribution and Filtering - 2.3L EcoBoost (199kW/270PS), Removal and Installation).

1. When the pressure tests are complete, install the line pressure tap plug.
   
   • Torque: 12 Nm (106 lb-in).
     

1. Install the air cleaner.
   REFER to: Air Cleaner (303-12B Intake Air Distribution and Filtering - 2.3L EcoBoost (199kW/270PS), Removal and Installation).

  Line Pressure Diagnosis Chart

Stall Speed Test

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 DTC s 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:

1. Apply the parking brake.
   

1. Connect the scan tool. Navigate to Datalogger: PCM
   

1. Monitor the PID s: APP (%), RPM, LOAD (%) and GEAR_CMD
   

1. Start the engine.
   

1. Place the transmission in reverse.
   

1. Start datalogger recording.
   

1. With the brake pedal firmly applied, press the accelerator pedal to 100% for 2-3 seconds until engine RPM stabilizes. Release the accelerator pedal.
   

1. Place the transmission in neutral.
   

1. Press the accelerator pedal to maintain 1500 RPM for 10 seconds to allow the torque converter to cool. Release the accelerator pedal.
   

1. Place the transmission in drive.
   

1. With the brake pedal firmly applied, press the accelerator pedal to 100% for 2-3 seconds until engine RPM stabilizes. Release the accelerator pedal.
   

1. Place the transmission in neutral.
   

1. Press the accelerator pedal to maintain 1500 RPM for 10 seconds to allow the torque converter to cool. Release the accelerator pedal.
   

1. Turn the engine off.
   

1. 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
     

Air Pressure Test

  8F35/8F40 Air Ports

1. Using a high volume rubber tipped blow gun, apply air pressure to the suspect clutch port for 2-3 seconds.
   
   • A dull thud indicates the clutch piston is applied.
     
   • A hissing noise may indicate a leak in the hydraulic passages.
     

1. While holding the blow gun nozzle firmly against the port in the transmission case, release the trigger.
   

1. Wait 1-2 seconds.
   
   • A hissing noise may indicate a leak in the hydraulic passages.
     

1. Remove the blow gun from the port.
   
   • A sudden release of air pressure indicates the hydraulic passages are capable of holding pressure.
     
   • No noise may indicate a leak in the hydraulic passages.