Hi, I have a xjr-6 1995 . The transmission shifts good but when it's in top and going slightly down hill it shift into fourth. It doesn't do it as much when cold , also if you give it a foot full in fourth (red line) it won't do it for a while. It's not the fluid level , I change out the TCM and no difference. It was stood for about 12 mouths before I bought it , I've done about 2000 miles in it and there seems to be a slight improvement, maybe . Can anyone please help?
Thanks, Phil.

 

'Top' and 'fourth' are the same thing. It's a 4-speed automatic.

Presumably this is when going down hill with the throttle released? If so I think you might be feeling the locking torque convertor disengage


Perhaps I'm not correctly understanding the symptom, though.

Cheers
DD

 

Sorry , my mistake , I meant 3rd and 4th . It's with the throttle open and constant , then it goes back into 4th with and bit of a thump, at worst it does this about 4 times ever mile.
Thanks, Phil.

 

A locking torque convertor disengaging and engaging sounds like a possibility.

 

Is this an easy fix ?
Phil.

 

Let's try to narrow this down.

At, let's say, 60 mph the difference between 3rd gear and 4th gear will be several hundred RPM.....like 500 rpm.

The difference between a locked vs unlocked (engaged/disengaged) torque convertor will only be about 100-200 rpm.

Which best describes what you are experiencing?

If you think you might just be feeling the torque convertor.......

Does this symptom occur under any other driving circumstances?

Here's why I ask: it IS possible to inadvertantly find a sweet spot (or should I say sour spot?) where road speed, engine load, and throttle position put the torque convertor right on the very edge of being engaged and disengaged. As it result it hunts back and forth....trying to decide where it oughta be.

Trying going a couple MPH faster or slower, or try altering the throttle opening just a bit. If the symptom goes away then you can be pretty sure that you've simply be driving in the sour spot.

However.....

While this torque convertor hunting (if that is indeed what you're feeling) in the sour spot is generally benign it shouldn't be particularly harsh or disturbing. Shouldn't like a hard jolt. Should be more like a mild jiglle. If it harsh, you might have a problem.

Cheers
DD

 

Hi Doug, Thanks to your thought provoking answers . I think I was wrong in my assumption the problem was between 3rd and 4th , rather the torque converter lock up engaging and disengaging as the rpm only alters about100- 200. it does this between 55mph (after 4th has engaged) right up to 120mph, the fastest I've been . The jolt is just a little uncomfortable , not enough to be scared over.
Appreciate your help, Phil.