U decsribred mine to a tee. I did a trans flush, reflash and added the Jaguar modifier. Still the same outcome. I have drove the car 10k miles without any other problem. To me it seems like two different temp sensors are fighting over what program to run. Simular to different fuel curves from a warm engine to a cold one. Why else would the problem go away when it warms up. It's like the trans says its to cold to engage the converter, but the engine sensors says we are warmed up enough to engage the converter. Sorry, just thinking out loud.

 

I have heard it was torque converter lockup however the ECM will not give the command to lock up the torque converter under the following conditions:

1. when the engine is cold
2. vehicle is not in 6th gear
3. the brake is depressed.

I stand corrected. This transmission will lock up torque converter in all 6 speeds if needed
here is a link:
http://en.wikipedia.org/wiki/ZF_6HP26_transmission


This problem, on my car, will do it under those circumstances.
Mine feels as if it is attempting to go into two different gears at once. Once I hit passing gear or a few brisk shifts it goes away.
My guess is its a programing/learning problem

 

I do believe the ZF transmission can lock the converter as low as 3rd gear. Mine has deffinitely hunted in 5 and 6.

 

I put the gear selector into 3rd until the car warms up to minimize the hunting between gears. Even in 3rd it will hunt a little at low speeds however it's much better then leaving it in "D". It's not a fix however it does the trick. The only fix I've been told is to replace the torque converter.

 

That is correct. From the X350 training guide:

Torque Converter lock-up Control
The TCM controls how the torque converter clutch is engaged as a function of:

Pedal position
Output speed
Oil temperature
Gear selected
Shift program

Lock-up is possible in all forward gears, but usually it is restricted to third fourth, fifth and sixth gears (4th to 6th for S/C variants).

 

I did notice it was hunting in 4th yesterday. It's still weird, why does it stop after the trans warms up?

 

As Microsoft would say, "it's not a bug, it's a feature" !

 

My 2004 XJ8 transmission has been "hunting" for about a year and a half, even after a rebuild. The trans guy has bent over backwards, had the dealer reflash several times, replaced the valve body twice, and done everything except replace the torque converter.

I've read all over this forum but I don't recall seeing a true documented resolution.
I'm ready to take the next step, but I need at least a few confirmed success stories to have the confidence that the torque converter is the culprit.

Has anyone actually had the transmission "hunting" issue resolved?
What did it take?

Any help is greatly appreciated.

 

Go back to page 1 of this thread and look at post #3. He apparently replaced his torque converter and it fixed the issue. Perhaps you can ask him about the details.

 

If this issue is as pervasive as the posts indicate, I think a few more confirmed resolutions would be expected.

So yes, we have one confirmed torque converter "hunting" resolution.

Any more?

 

Mine does it too, 04 XJR.

 

It fixed it or you have this problem as well?

 

It does it, and is not fixed. What I wonder is, is the hardware(torque converter) different on the '04 model? If not, then a software update would seem to be in order.

 

I tried a reflashing and a shift adaption this last Saturday and it didn't help. The trans is flawless once warmed up, but hunts cold. I thought jag modified the converter in 05?

 

As I said before, its not a bug, its a feature. There seems to be a problem with the engine management software when the car is almost up to temperature, but not quite. My car does it, you just have to get used to it. I don't suppose Jaguar are going to spend a lot of time on it now unless the new XJ does it.

 

One of the conditions affecting ability to lockup is the temperature of the ATF. If the ATF is not all at the same temperature, but some of it is hot, then the temperature sensor will see it, and then see cold shortly afterwards as a slug of colder ATF passes by.

At a guess, the unfixed software sees hot, performs lockup, sees cold, disables lockup.

The flash might be an attempt to put a delay in lockup but the algorithm is still twitchy.

The best algorithm would be "do not lockup until after temperature has remained above lockup threshold for X minutes".

This may be why a couple of "hot shifts" makes the problem go away. Those shifts warm up the fluid and mix the fluid.

It might be tempting to blame the software engineers, but maybe they are operating under constraints such as maximising gas mileage at the same time.

 

It really is frustrating. I had the car reflashed once, do you guys think it is worth attempting it again?

 

I went to a Jaguar Enthusiasts Club seminar on the X350s yesterday. The person who took us through all the various known issues is an independent Jaguar specialist. There is no consensus on what causes the hunting. There is a lock-up clutch in the torque converter, and there is the possibility of fluid leakage past an internal seal causing this hunting but also the possibility of a software issue between the ECU and the gearbosx controller. He also poinnted out that he had never had to do a gearbox replace on this issue, and most owners accepted it as a feature to be endured, as it only happened in the last stages of warm-up, He has an XJR with the hunting and will be keeping an eye on it and advise club members if anything further happens. The club are setting up a new forum for the X350s and this specialist will be providing service, faults, and maintenance advice.

Main message of the seminar was how reliable and well built the cars are, and this from a chap who has Jaguars in for service and fault repairs all day and everyday.

 

Just bought a very clean 2004 XJR with 47,000 miles. Took it in for a checkup, and dealer said trans pan was seeping a bit, not dripping, and to change the pan, with new gaskets would be $800. The hunting condition would be another $200 to reprogram and the trans fluid is $55 per pint.

Does this seem reasonable to anyone? Too high to me, and why are the trans pans plastic? When I asked about just changing the gasket, they said no guarantee it would stop the seeping. You have to change the pan. Does anyone make a better replacement trans pan?

Any recommendation on this are much appreciated. Thanks for your feedback.

 

If it is only seepage and no drops I would just monitor it. Often times seepage never gets any worse.
I wouldn't pay 10 cents for the software update again. the hunting returned within a month of paying $150.

My wife drives the car mostly and she doesn't notice it. When i drive it and it hunts, I hit passing gear and it goes away. I still feel it is a software problem and it can't be truely fixed without replacing the module. (TCM) The current one (processor) can not handle some of the parameters the transmission experiences. (my opinion only)