tranny shifts in neutral when braking hard

[neo4you]

I have a 2000 LS V6 with 118K which I bought about a year ago when it had like 102K on it.
Last summer, the tranny started acting little wild. My previous car wsa 94 MakrVIII, so I'm I guess I'm getting used to transmission problems in Lincolns
Anyway, here's the problem - say I'm doing around 45-60 mph, then brake pretty hard to a complete standstill, then try to continue driving (you know, like stopping at a STOP sign or whatever). But the RPMs would go up, and the car is still not moving, then maybe a second or two after it will jerk and finally start accelerating. It seems like it shifts into neutral and then back into gear. Few times it even stalled (but this might have been a separate problem - I've changed coils&plugs and it never happened again). I took it to a dealership to do transmision service - fluid&filter (some LS owners with similar problems told me it fixed theri issues), but it didn't help.
If I brake nice and smooth, this whole thing doesn't happen.

Do you guys have any ideas how to fix this?

Any help will be appreciated.

 

[2001LS8Sport]

It sounds to me like the hard braking is forcing the fluid away from the pick up in the tranny pan and cavitating the pump. This is actually a common problem on race cars with engine oil pans and many use exotic pans and baffles to control this. In your case, I would guess you are low on transmission fluid. It might be time to take the car in and have the tranny serviced and filter changed. I'm betting that takes care of it for you.

 

[neo4you]

Well, I already did take it for service. Just like I said in the original post, other LS owners told me exactly what you wrote, but it didn't help. Maybe I should take it back and tell 'em to re-check the trans fluid level...

 

[Jim Henderson]

Wild guess is that the Torque converter lockup is sluggish or failing. When you hit the brakes the TC will unlock. When you hit the gas, it should lockup again relatively soon. There should still be some power to the wheels but the RPM will be higher.

Also, if the converter locks when the car is stopped or slowing a lot, it may bog the egnine down and make it stall.

Like I said a wild guess but the symptoms kind of fit your description.

Good Luck,

Jim Henderson

 

[2001LS8Sport]

Well, I already did take it for service. Just like I said in the original post, other LS owners told me exactly what you wrote, but it didn't help. Maybe I should take it back and tell 'em to re-check the trans fluid level...

Yes you did state that! I apologize! Were you having this problem prior to servicing? If so, I would doubt it's the problem I described. If the problem is post servicing, I would most definitely have them recheck it!! Make sure it's full of fluid and the filter isn't loose or something dumb like that and sucking air because of that.

 

[neo4you]

I took it back, they added more fluid, but the problem is still there. I took it back again today and they're going to hook it up to the computer to see if there are any error codes. So I'm waiting for the results.

I think Jim is right. It does seem like a problem in torque converter.
My dealership is probably going to charge me some crazy $$$ for that.