It doesn't "shut off" you torque converter, it simply prevents it from locking up. You need some background info on how an automatic transmission works.
You torque converter constantly allows slippage. The harder you accellerate, the les slippage you get. The slower you accellerate, the more slippage it allows. Once you reach a certain speed, you torque converter "locks up", and doesn't slip any more. Once you slow down, the torque converter "unlocks", and starts slipping again. This is the way it's designed, to promote fuel economy and longevity.
But it my case, and probably in your case as well, your torque converter does not "unlock", therefore when you're sitting at idle your torque converter is locked up and won't slip, causing your car to stall. Intermittently it will go into gear fine, but more often than not it will stall when put in gear if you're not giving it gas at the same time (ie: neutral drop
).
The switch can be accessed by removing the air cleaner. I'm not sure exactly what you have to do to disconnect it, but most likely it's as simple as removing an electrical connector. I believe its called (go figure) the Torque Converter Lockup switch (a.k.a. overdrive switch).
Don't fret - if this is your problem (more than likely) it's a 5 minute fix by someone who knows what to do. My brother-in-law (who is a mechanic and immediatly diagnosed the problem based on previous experience) disconnected in in about 5 minutes in the dark!
Also, just F.Y.I., the '91 Sunbird this was done on has been running fine for the last 3 years with the overdrive disconnected. It doesn't get great highway fuel economy, but a '91 3.1 V6 w/ 280,000km really shouldn't!
