Lurch/Lung in Transmission

[jookul100431]

Hi

On the way home this I noticed that the gear changes on my 2.7 sovergin diesel were not all that smooth they seemed a bit lungy and I noticed that the it seems to hold onto 3rd gear longer than I would normally expect...I have been noticing this from time to time only really when the car is cold. It does seems to be better when the car is hot.

We did change the filter and oils about 3 months ago using proper zf filter and oil and I must say I can't determine if this had any impact.

I understand there is a learning process that the car must do when the battery is disconnected and if u follow the workshop manual it takes about 40mins to complete. I must admit the last few times I have disconnected the battery I have not done the full reset procedure I have just driven as normal.

Can the box be reset..it is advised. I have read about software updates and have no idea has my car been updated....is it a 2007 car but looking at the history I would say it has been out of the dealer network for about 8 years... I'm assuming it's not oil and filter as this has been done

I am thinking easiest is maybe unpulg battery and do full learning process as set out in the manual

If not better see if the box can be rest

After that check sw updates with dealer

Then if still no good do another oil change...btw I am assuming my oil level is correct....may have to get mechanic to check that first

Any thoughts

[J44EAG]

A transmission ECU re-flash often forms part of a reputable maintainers all in costing for the job. This is done once the car has had its oil, filter/sump and connector sleeve replaced and after the transmission has attained a specific temperature. At that point, oil level is adjusted while the car is still on the ramp. Adjusting oil level is only done at a specific temperature which allows for fluid expansion. It should not be done cold and by an experienced operator who is doing this type of work on an everyday basis.

You could do a hard dump re-set by battery disconnection if and only if you feel confident of the procedure. It might though be more satisfactory to find a well qualified gearbox maintainer and just leave the technicalities to him. These cars were never meant to be DIY serviced so I`d favour putting this high tech work out to knowledgable professionals. Its a lot less bovver in the long run.

Mike K

[jookul100431]

Hi Mike

Thanks for the reply...I do tend to agree with u once this gets beyond me and to be honest that is some resets like pulling the battery and leaving for a few hours and doing the proper relearn procedure...beyond that it's a professional. I live in Ireland so unfortunately trying to find good specialist are not as easy as uk. If the problem persists it maybe main dealer...I'm not too concerned at the mo. Though I will go through the various options

I did find a tech bulliten and aon the jaguar forums about a relearn process. So I tried that this morning. Will have to wait till tomorrowmorning to see if it made any difference. Though I don't think it will

I have read a lot on various boards about a hard reset... disconnected positive and negative and then short positive to ground....my back ground is electronic engineer so I understand the logic of discharging residual current and not doing any damage...but I don't know the one and outs of the electronics of this car and feel a little aprihensive. But I may go there yet....

On my last two Mercs there was a way of resetting the gearbox via hidden menus on the car itself. But Jag don't seem to have that option. I'll move slowly and cautiously on this one as I dont want to f up the box.... I have attached an image of the thread I found for information. I also did find 2 or 3 versions of a tech bullitens which pretty much say the same thing

[J44EAG]

Disconnection of the battery shouldn`t cause issues. Leave disconnected for at least twenty minutes. I`ve never bothered to touch the +Ve and -Ve cables together. Before getting a diagnostic unit, my poor mans way of clearing codes was just disconnection of the battery. No problems and no issues.

Worth noting that sometimes even the best code reader can`t clear a stubbornly lodged code. Even professional garages sometimes resort to this hard dump method. The practice is very common.

As I recall, after a hard dump, you have to teach your car your driving style. I used to drive the car hard for half an hour, then keeping my foot on the brake pedal, I would switch off keeping the brake pedal held down for another thirty seconds...... That would confirm the learning process to the Drive Train ECU. Job done.

Mike

[jookul100431]

Thanks Mike o might that approach....there is all sort across the Google about different ways to reset. Never heard your method so might give that a go.....
....so far I have carri d out the reset method mentioned on previous post....my biggest problem there was that I could not get the car to go into 5th gear below 2000 rpm no matter what I tried. So I am not certain if it worked correctly. Also not certain if it made any difference.

On Thursday morning I called into my mechanic and he was able to reset the gearbox adaptations. So from what I understand it is relearning at the mo. Bit not sure if that is correct. Also so far it has made no difference.

My biggest challenge here is that when I say it's lurching I'm not too sure how bad it is on compersion to other cars. So maybe if u drove it u might say it was quite good. I have experienced that little kick u get just as the car changes into first when I are nearly stopped. An the other thing that Sims to be a bit odd from time tome is that the revs will go higher by about 200 rpm just as it changes gear. But it does not do this all the time and not in all gears....not certain am I chasing ghost.

[ptjs1]

jookul100431,

The surge when changing down to first is a known issue that is usually cleared when the adaptations are performed on the car. If the oil and filter are new and the oil level has been set correctly using the appropriate fill and temperature setting, then I would thoroughly recommend that you pay to get a good Jaguar independent, or even main dealer, to perform the adaptations. Then see if that has cured all the problems.

Good luck

Paul

PS Check that you're not in Sport mode, if the car won't change up to fifth, when warm, on a flat surface, at 1750rpm.