If Shudder Occurs After TCC Has Applied

If shudder occurs after the TCC has applied, most of the time there is nothing wrong with the transmission.

As mentioned above, the TCC is not likely to slip after the TCC has been applied. Engine problems may go unnoticed under light throttle and load, but they become noticeable after the TCC apply when going up a hill or accelerating. This is due to the mechanical coupling between the engine and the transmission.

Once TCC is applied, there is no torque converter, fluid coupling, assistance. Engine or driveline vibrations could be unnoticeable before TCC engagement.

Inspect the following components to avoid misdiagnosis of TCC shudder. An inspection will also avoid the unnecessary disassembly of a transmission or the unnecessary replacement of a torque converter.

• EGR Valve
  
  The valve may let in too much or too little unburnable exhaust gas and could cause the engine to run rich or lean.
• Carbon On Intake Valves
  
  Carbon restricts the proper flow of air/fuel mixture into the cylinders.
• Flat Cam
  
  Valves do not open enough to let the proper fuel/air mixture into the cylinders.
• Fuel Pressure
  
  This may be too low.
• Engine Mounts
  
  Vibration of the mounts can be multiplied by TCC engagement.
• Axle Joints
  
  Check for vibration.
• TP Sensor
  
  The TCC apply and release depends on the TP sensor in many engines. If the TP sensor is out of specification, TCC may remain applied during initial engine loading.
• Cylinder Balance
  
  Bad piston rings or poorly sealing valves can cause low power in a cylinder.
• Fuel Contamination
  
  This causes poor engine performance.