2003 XKR WANDERING GEAR CHANGE

[simonmahoneyuk142]

Hi all
I have had two xkr's one 2002 and my current beauty a 2003 convertible.
Both have the same problem. When cold the gearbox seems unable to make its mind up which gear it should be in. This results in it wandering around aimlessly between gears regardless of terrain
I am having the gearbox flushed and a GB oil change, its done 46k but not sure this is the cause.
Anyone had the same problem and found a solution?
Thanks and have a wonderful, safe and happy Christmas and New Year
Simon

[Astromorg]

46k miles is a little early to need a fluid change, but depending on how it's been driven over the years, it may help to change it and if done in the approved manner, with the right fluid it will not do any harm and will give a known position from which to consider other angles. Any signs of a fluid leak that could over time have dropped the fluid level? Presumably no warning messages or lights as you don't mention them. Low fluid level does cause various problems.

Without knowing anything of those who are doing the fluid change for you, in case they are unaware, the level needs to be set with the gearbox at a temperature between 30 and 50 deg C, with the engine running and the selector in Park. The correct fluid is ZF Lifeguard Fluid 6.

Additionally the sump of the gearbox that houses the filter should be changed as should the seal arrangement for the electrical connector while the sump is off (A common leak point!)

There is in the Workshop manual an interesting paragraph that is the only reference I can find re 'hunting gears'. Sadly it doesn't really open any doors to how this hunting might be controlled and of course all of the listed g'box faults (of which there are many!) all come with a fault code and warning light/message

Adaptive Shift Strategies

The TCM of the six speed ZF automatic transmission incorporates adaptive strategies which improve the accessibility of the vehicle`s performance in driving conditions while maintaining a relaxed driving experience when cruising.

In 'Sport' mode, accelerator pedal usage and cornering behaviour are monitored to assess driving style and road conditions. When an enthusiastic driving style or a demanding road is detected, 6th gear is inhibited and the lower gears are made slightly more accessible in order to prevent unwanted 'hunting' between gears.

Conversely, when cruising conditions are detected, 6th gear is once again made available to maximise driving refinement and economy.
Under conditions of heavy braking, the transmission will perform one or more downshifts to improve response to a subsequent accelerator pedal application. Similarly if the accelerator pedal is released rapidly following hard acceleration, one or more upshifts are inhibited to increase engine braking and also improve subsequent response.

To complement these features, when a corner is detected transmission upshifts are inhibited. This inhibition is also maintained for a short distance after the corner allowing the driver to achieve a smooth balance through the bend without unwanted shifting mid-corner.

[simonmahoneyuk142]

Wow, what a comprehensions answer. Thank you so much
Will heed advice. Oil change is being done by a known to me Jag specialist (Collier Street Jaguar in Tonbridge), who has done quote "hundreds"
Thanks again very much appreciated. I will wait to see if any others have experienced the same
Simon

[Astromorg]

It will of course be appreciated by those with this hunting problem in the future to know the outcome of your fluid change so please keep the thread updated as to whether it helps or not