For 1990-2009 cars

1. Inspect the engine flywheel and the torque converter for loose or missing torque converter-to-engine flywheel bolts. Tighten or replace the bolts as necessary. Refer to Engine Flywheel Replacement and/or Flywheel to Torque Converter Bolt Replacement in Automatic Transmission/Transaxle.
2. Inspect the torque converter for damaged or missing balance weights. Replace the torque converter if the torque converter is damaged or if any balance weights are missing.
3. Change the position of the torque converter to the engine flywheel 120 degrees at a time in order to cancel out an engine and torque converter imbalance. Check for vibration improvements in each position.

Important: Check to make sure that the engine flywheel-to-torque converter bolts do not bottom in the holes. Rotate the torque converter by hand after adding the washers.

4. If the unbalanced condition continues, leave the torque converter bolted to the engine flywheel in the best balanced position. Install longer engine flywheel-to-torque converter bolts, and add or remove washers in order to achieve the best balance.