XJ6 gearbox

[Henry Harris]

I own a 2006/56 XJ6 2.7 diesel Sport Premium automatic, which is beautiful car to look at and drive. However, I have a couple of symptoms with the gearbox that I would like to share and seek an explanation.

When the car is cold, left overnight, for the first couple of miles driving, the engine speed goes back to idle when lifting off the throttle. It is as if the car is in neutral; there is no engine braking; the car is freewheeling.

The second symptom is when lifting off the throttle at about 40 mph, the car slows and I can see the gearbox changing down. As the speed drops just below 30 mph, the car appears to drop into neutral; as before there is no engine breaking. It is as if the mapping of the gearbox dictates that I am about stop and does not bother to select a lower gear. Whilst still rolling, if I accelerate the engine revs pick-up, but in my opinion in a too low gear.

My query is, are these symptoms normal gearbox characteristics for this car?

Thanks in anticipation.

[a8hex]

I certainly don't remember the one I've driven doing this. Not giving engine braking below 30MPH is something I would have noticed. That sounds very wrong.

[x200sxy]

Why not dump it at the stealer, it must be under warranty?

[Bat21]

I have just taken delivery of an 07 X358 sovereign 2.7, I've only done a few hundred miles,so far the only thing I have noticed is that when cold, the box holds onto gears and keeps the revs up until normal operating temp is achieved,otherwise it's as smooth as a smooth thing bieng smooth. You may have a software issue.

[Henry Harris]

Thanks for that last post.

That is exactly the symptom I get when the engine is cold - a reluctance to change up. However in that same warm-up period, the revs drop right away when I lift off the throttle.

By the way, the main dealrer say that they have fixed it; mine is better than another one that they have tried. That's no answer to exactly what are the characteristics of the gearbox under the conditions that I have described. Guess what - nothing has changed.

Edited by Henry Harris on Thursday 20th November 20:03

[Jaguar steve]

It was the usually the case a few years ago that autoboxes were programmed with a bias towards holding lower gears to promote a faster warm up of the engine to get the catalysts working efficently as soon as possible.

[Henry Harris]

Where do I go now?

A service representative from the main dealer that I have been using has stated that they do not talk to Jaguar. A representative of Jaguar Customer Services has stated that Jaguar does not give out technical information over the 'phone.

Where do I go and how do I get technical information on the gearbox operating characteristics covering the conditions described by the symptoms in the earlier post?

Edited by Henry Harris on Tuesday 25th November 16:07

[a8hex]

I seem to remember from somewhere way back that it isn't actually legal to put a car in neutral and just freewheel down hill. If that is the case then the gearbox could not have been type approved as it is. If the car is dropping out of gear then I'm sure it is wrong. Not sure what is done these days, but back in the pre cat days, fuel injected cars typically actually cut all fuel supply when engine braking with the foot off the throttle. I suspect that this would make things too hot for cats during the on or off phases, but I could be wrong. Have you experienced it on a steel hill? here you certainly would want an auto to drop out of gear during a descent.

If the car is still under warrantee then I'd try another dealer. I'm sure main dealers will be able to call Jaguar to further assistance.

[Henry Harris]

The latest:
Jaguar does not give out technical information to customers like me to protect my interests.
An independent gearbox specialist informs me that:
a) The symptoms when cold are to allow the catalytic converters to warm up
b) The symptoms under normal driving conditions are expected and are due to the gearbox lock-up mechanism.
Any comments would be welcome.

[Jaguar steve]

If you're not happy with the response you've had so far then perhaps it's time to try another dealer.

Either it's got a fault - in which case as it must still be under warranty - they'll fix it, or if there's nothing wrong with it they should be able to let you drive another one, or talk to a mechanic, or contact Jaguar on your behalf and get a factory rep to drive it with you as a passenger or do whatever else it takes to put your mind at rest.

Modern cars do have odd operating quirks - like holding on to lower gears to get the cats working quickly from a cold start - so it may just be doing somthing you think isn't quite right or you are not familar with - but is actually OK.

[Henry Harris]

Thanks for your reply post.

That is exactly what I want Jaguar to say - what should the gearbox symptoms be under these circumstances. I sense a distinct reluctance.

[a8hex]

Does any else here have an X350 and get these symptoms?

You could also try asking in the X300 forum on Jag-Lovers to see whether anyone else the same behaviour.

[cardigankid]

I had an X350 and while I never had any significant issues with it any warranty questions were dealt with instantly. Try another dealer.