A/T - Shudder
91mitsubishi04
NO. TSB-91-23-004
DATE February, 1991
MODEL 1990 Mirage
SUBJECT: 1990 MIRAGE AUTOMATIC TRANSAXLE SHUDDER
PURPOSE
Some 1990 Mirage vehicles equipped with a 1.5L engine and an automatic transaxle may exhibit a shudder when driving in higher gears under light acceleration or load. This condition usually occurs at speeds above 30 MPH and is most noticeable at approximately 40 MPH. The shudder is caused by the cyclical engagement and subsequent release of the automatic transaxle torque converter clutch and is felt about 1 time per second. The diagnosis and repair procedure contained in this bulletin should alleviate this condition.
PARTS INFORMATION
Diamond ATF SP: MS991154
Transaxle oil pan gasket: MD707183
Differential oil plug gasket: MF660035
WARRANTY INFORMATION
Standard warranty procedures apply.
PRELIMINARY DIAGNOSTIC PROCEDURES
Allow the vehicle to warm up to operating temperature. Test drive the vehicle to determine the extent of the shudder condition.
Use the Multi-Use Tester to determine if any fault codes exist in either the ECI or Automatic Transaxle systems. If any fault codes are found, follow the diagnostic procedures shown in the appropriate service manuals until the codes disappear.
After the fault codes disappear, test drive the vehicle again to determine if the shudder condition persists. If it still exists, perform the following repair procedures.
REPAIR PROCEDURE
The repair procedure consists of flushing the ATF from the transaxle and torque converter.
1. Set the parking brake and place the transaxle shift selector in the neutral position ("N").
Figure 1:
2. Remove the left (Driver side) transaxle cooler hose from the radiator and place the removed end into a large drain pan. In order to reduce splash, connect a clear extension hose on the transaxle cooler hose (Figure 1).
3. Temporarily disconnect the ignition coil high voltage wire from the distributor and ground the disconnected end.
4. Crank the engine 10 seconds. Verify that the oil being flushed out is being directed into the drain pan.
5. Reconnect the ignition coil high voltage wire.
6. Remove the transaxle dipstick and set aside.
Figure 2:
7. Start the engine. Allow the engine to IDLE for 1 minute unless air bubbles start flowing from the transaxle cooler hose, or if the transaxle fluid stops flowing from the cooler hose (Figure 2).
CAUTION: To prevent transaxle damage, stop the engine immediately if the transaxle fluid stops flowing from the cooler hose.
Do not allow the engine to run above idle speed.
8. Reinstall the removed transaxle cooler hose.
9. Remove the transaxle oil pan. Remove all accumulated residue from the transaxle oil pan and from the screen.
Figure 3:
10. Remove the differential drain plug and allow the differential to drain for at least 1 minute (Figure 3).
11. Install a new differential drain plug gasket
(PN: MF660035) and reinstall the drain plug. Torque the differential drain plug to: 30 - 35 N-m (22 - 25 ft.lbs.).
12. Using a new transaxle oil pan gasket
(PN: MD707183), reinstall the transaxle oil pan and torque the bolts to 10 - 12 N-m (8 - 9 ft.lbs.).
13. Refill the automatic transaxle using Diamond ATF SP.
CAUTION: Do not use any other brands or type of automatic transmission fluid and do not overfill the transaxle.
14. Set the parking brake. Hold your foot on the brake. Start the engine and slowly move the transaxle selector lever through all positions.
Figure 4:
15. Recheck the transaxle fluid level. Adjust as necessary and repeat the preceding step until the transaxle fluid level is correct (Figure 4).
16. Check the transaxle and cooler hose connection for leaks.