AODE TQ Converter going bad, I think?

94_302,

I’ve been down this same path with the clutch plate surfaces in the lockup torque converter getting glazed and causing the shudder problem. Dr. Tranny’s Instant Shudder Fixx will cure it for a while, but eventually the clutch surfaces get so bad that you have to replace the torque converter.

Regarding your other problem. It sounds to me now like your entire torque converter lockup mechanism is starting to fail and actually unlock in OD while you are driving down the highway.

Bear in mind that when the car shifts from 3rd to OD the lock up does not happen instantaneously. It might seem that it does, but there is just a slight delay. First the speed of torque converter turbine (connected to the transmission input shaft) needs to nearly catch up to the speed of the torque converter pump (connected to the engine flywheel). As soon as that happens, the PCM (power train control module) signals the torque converter lockup clutch to engage and physically lock the turbine and pump together making them turn at exactly the same speed. (At this point, the transmission no longer serves as a fluid coupling, but as a solid mechanical connection between the engine flywheel and the transmission input shaft.)

The same process happens in reverse when you downshift from OD to 3rd. First the lock up clutch plates disengage, unlocking the turbine from the pump. When this happens the transmission actually operates in OD for a very short period of time before it downshifts into 3rd . All of this happens pretty seamlessly and so quickly that most people don’t notice.

You can actually conduct a little road test to observe it happen when downshifting from OD to 3rd. Find a nice long road with a slight uphill grade and start up there in OD. Then push the OD On/Off button to cycle the OD OFF. As soon as you do this you will immediately notice a slight increase in RPM when the torque converter lock up clutch disengages. Shortly after that you will notice a second, more significant, increase in RPM when the transmission actually downshifts out of OD and into 3rd.

This is actually a pretty good test to see IF your lock up torque converter is working properly.

All that said, I think your torque converter clutch plates are now so far gone that even with the lock up engaged it cannot hold the turbine and pump together and keep them from slipping.

Note: A possible second cause for this type of transmission symptom may be a MLPS (manual lever position switch) that is going bad. The MLPS is mounted on the outside of your transmission and tells the PCM what gear the transmission is in. This can easily be changed out without removing the transmission from the car. I think they cost around $50 bucks.

Hope that helps. Good luck.