I have searched around the forum and not found anything quite similar, so I will ask and see if anyone has any similar experience or insight.

Problem:
When accelerating, my X revs up and then shifts. But when it shifts, under "normal" acceleration, there is a delay from 1st to 2nd, 2nd to 3rd, etc. It's just a little hesitation for a split second, not a 3 second delay or anything. But the nose of the car dips down, and you can feel the loss of momentum. It makes getting up to speed not much fun.

Now if you stomp hard on the gas, this effect is much less noticeable.

The flip side of this is that when you let off the gas and coast, it seems to downshift early, and again the nose dips and you lose momentum like you stepped on the brake. It also doesn't coast well, like the brake is on. My XK8 and for that matter, my daughters 1998 minivan both coast easier. The X will lose speed when coasting downhill! This effect is reduced in neutral, and increased when the car is cold.

I had the dealer replace the transmission fluid a year ago - no effect. That was $900 down the drain. Although they did say the "lifetime fluid" was dark and burnt, so still glad I did it.

I am in the middle of replacing the transfer case oil, have done 2 fill and drains so far as a poor mans flush. There was appx 70ml of oil in the case when I started, and what appeared to be shoe polish on the plug. This does seem to have helped a little, but not 100%.

Car is a 2006 and has 107k miles.

Differentials? Prop shaft bearing? Gremlins? Would appreciate any suggestions or leads! Thanks all.


PS thanks to those who contributed on the t-case oil replacement. It's amazing the amount of help you get here. I could never have done that (or several other things) without the excellent folks here sharing their experiences.

 

Sorry to hear about your problem. I think this result can stem from 2 different areas:

1) An actual transmission shifting issue
2) Some sort of engine problem (like running rich/lean) that has not yet triggered a check engine light but is still throwing off the cars' computers and causes the lack of power. You'd be surprised how closely tied in transmission shifting is to a properly running engine.

Remedies:

-Try disconnecting both terminals from the battery and waiting around 5 mins before connecting back again (this seems to erase any learned shifting parameters the car adapted and resorts to a factory default setting. From here you can even get your car to shift around 4000 rpm during normal driving like I did just by driving aggressively around town.

-Try cleaning the MAF/air filter/Throttle Body (lots of instructions here)

-Replace/Clean Spark Plugs

-Check for any small vacuum leaks

~best of luck

 

I just experienced the same problem with my 03 x type transmission. I am the second owner and knew the car had not been hurt in any form when I owned It so I was at a loss. Finally when mine started shifting so hard from 1st to 2nd I thought maybe its the transmission fluid. Little did I know the fluid was only checkable from underneath. Mine had never been checked since it was manufactured apparently and was 2 quarts low. Hindside > the car shifts smooth as glass 1st thru 4th but on the ride home.... reverse is now out completely. So I waited to long.


Long story short the revving up and shifting hard is exactly what mine did.