I recently noticed the following in my 2000 S-type 3.0...

When taking a highway on ramp I have to accelerate quickly.

In doing so, I noticed that my car hesitates and it feels like the tranny is quickly switching back and forth between gears. This usually happens as I am accelerating quickly and approach the 80km/h(50mph) - 100km/h(60mph) range.

Once the car is in top gear, it is perfect and there are no issues dropping down a gear when I then have to pass someone on the highway.

No codes have appeared.
Tranny fluids are good.

Has anyone experienced this before?

 

Be sure to check for vaccume leaks and that the tran. shift linkage is set correctly. Did you mean that the trans. fluid has the correct level or recently replaced? If there is over 75k miles on the trans. fluid you should replace the fluid and filter.

 

A possibility is misfires which then lead the car not to quite know what to do with the transmision. Misfires are usually caused by an air leak or coil(s) but can be plugs or other issues.

Another is torque convertor trouble.

 

Yep, agreed.

 

Do you get "restricted performance" when it hesitates? Mine started off just feeling sluggish. Then, when I really got on it (let it rev to redline), it would trigger "restricted performance" and start to studder real bad until the light would go out and it would go back to normal. Once the light triggered, it was able to produce codes. It was recording misfires on all bank 2 cylinders. It ended up being a failed catalytic converter that was causing the issue. Dealer replaced the cat and all as been good since.

 

The tranny fluid was replaced 5000km(3000m) ago.
I will check for a vacuum leak... Thanks.