Shudder Occurs After TCC has Applied

Most of the time nothing will be wrong with the transaxle. Engine problems may go unnoticed under light throttle and load, but become noticeable after TCC is applied when going up a hill or when accelerating, due to mechanical coupling between the engine and the transaxle.

Inspect the following components to avoid misdiagnosis of TCC shudder and possibly disassembling a transaxle or replacing a torque converter unnecessarily:

Spark plugs

Inspect for cracks, high resistance or broken insulation.

Plug wires

Look in each end. If red dust or black carbon is present, the wires are bad. Also look for a white discoloration of the wire indicating arcing during hard acceleration.

Coil

Look for black on the bottom, which indicates arcing while the engine is misfiring.

Fuel injector

The filter may be plugged.

Vacuum leak

The engine will not get the correct amount of fuel. The engine may run rick or lean depending on where the leak is located.

EGR valve

The valve may allow too much unburnable exhaust gas and cause the engine to run lean.

MAP sensor

Like a vacuum leak, the engine will not get the correct amount of fuel for proper engine operation.

Carbon on the intake valves

This restricts proper flow of air/fuel mixture into the cylinders.

Flat cam

The valves do not open enough to let the proper air/fuel mixture into the cylinders.

Oxygen sensor

The engine may run too rich or too lean for too long.

Fuel pressure

The fuel pressure may be too low.

Engine mounts

Vibration of the mounts can be increased by TCC engagement

Axle joints

Inspect for vibration.

TPS

The TCC apply and release depends on the TPS in many engines. If TPS is out of specification, TCC may remain applied during initial engine starting.

Cylinder balance

Bad piston rings or poorly sealing valves can cause low power in a cylinder.

Fuel contamination

This causes poor engine performance.