I just bought a 2004 XJR with a known issue with the adaptive cruise module. I bought the car planning to replace the adaptive cruise module a few months down the line.

The car has various miscellanous issues, which the seller says most will fix once I replace the adaptive cruise module (the steering column adjust function doesn't work; heated seats don't work). But most critically, there is something weird going on with how the transmission behaves, and I am afraid it is a transmission issue (the seller says it will be resolved once I replace the adaptive cruise).

I bought through ebay, and there is a guarantee against drivetrain problems within the first 30 days, but it may not be realistic for me to replace the adaptive cruise within the timeframe to prove that the issues I am seeing is not related to that.

Here are some of what I am observing:
- When I am in certain gears (hard to tell, maybe the 3rd or 4th gear), the gear does not feel like it is staying connected (the car slows down a bit and the engine surges a bit) before going back to normal, intermittently.
- When I am going down the freeway at 50 mph, and press the gas sort of with the intent to do an aggressive passing maneuver at 70 mph, the engine surges upwards to 4000-6000 rpm, but there is no acceleration, for a whole second or two, and it seems to be taking an inordinate amount of time to "connect" and start accelerating.
- But I am not getting any transmission fault type errors or codes

I took it to a local Jaguar dealer but they charged me two hours to give me a non-definitive and unsatisfactory answers, telling me I need new tires, the surging is due to the tires being bald and spinning (I know it's not the tires spinning) and need new adaptive cruise, and being unable to do any more troubleshooting because the car needs a second key to do some troubleshooting steps, and they won't cut keys for me until the title is fully transferred etc.

Can symptoms like I describe really occur from the adaptive cruise module not being functional?

Are there things I can or should do to prove this is transmission or other powertrain related issues within the two weeks or so I have left on the drivetrain reimbursement guarantee from ebay?

I appreciate any suggestions or experiences that can help shed some light on things so I can take maximum advantage of guarantees in place before the time runs out.

Thank you.

 

I have been doing more detailed reading of the forum on this issue, and am now suspecting the symptoms can be accounted for by a faulty torque converter. What is the typical parts cost for a new torque converter? What is the typical labor cost? Can this be installed by an independent repair shop, or does it inherently require diagnostic equipment only the dealer has?

If I ignore this problem, because it is not too severe, am I unduly risking damage to the transmission or other components?

It looks like the transmission is covered by the ebay guarantee, but not the torque converter, so if this turns out to be the problem, I may have to pay to fix this, or try to negotiate with the seller for an undisclosed problem that came with the car.

I appreciate any feedback from anyone with any experience.

 

The symptoms during driving that you mention definitely point to the torque converter. There were problems with the early cars. This repair runs about $2500. I doubt that the problems you mention are related to the cruise control.

 

Hi Eric,

Take your car to Jaguar of Seattle (located in Lynwood). I had the best experience with them. Avoid Jaguar of Tacoma. The Bellevue dealers is OK, but I got the impression they don't want to do a lot of preventive work for some bizare reason. Don't tell them you got the cat from eBay cause they got ticked off by that. Tell them you got it from a private party.

Not sure why you would need a second key for troubleshooting.

I think you should get the problem diagnosed (discovered and documented) withing 30 days to qualify for the eBay warranty.

 

From my experience, the only issue with the torque converters is hunting of the RPM at constant speed when the torque converter lock up. Your problem doesn't sound like that. But....if I am driving in NORMAL mode at about +50 and press the pedal down without pressing the kick down button. The car will only shift to 5th gear and the acceleration is not great. If you fully press the accelerator and kick down button the car will shift to 5th and then to a lower appropriate gear, I think 4th. It's a little annoying and does have some lag. Have you tried doing the same think in SPORT mode? It's a much faster shift and I think it will skip the 5th gear shift. There are TONS of sensors on these transmission that look for how long it takes to shift, how much slip happens between shift and tempature. If you have a major problem it would be flagged.

 

I have a 2004 XJR, trans shifts funny into 1st and then to second gear with a noticeable
clunk anyone have an idea on this problem

 

Just to follow up on this issue, I just recently did a service on this transmission (ordering the plastic type transmission oil pan with built-in filter, ZF oil, etc. from the site recommended on the sticky note), and the people who serviced it said how remarkably good a condition the transmission was in, considering the 80,000 miles, i.e., the oil looked good, there was no metalic debris at all stuck to the magnet, no sign of any wear and tear, etc.). So I tend to conclude my concerns were just based on my not being used to this kind of transmission and its characteristics.

I may have the dealer check if the shifting algorithm/software needs to be updated, as I have read about cars with a VIN ending at less than G13700 has an older, less smooth shifting algorithm, but it seems like everything is in good shape.

I think since the oil change, the transmission seems smoother overall.

An interesting piece of trivia I learned while at the transmission shop -- that the Lincoln Navigator uses the same ZF 6HP26 transmission.

Anyway, thank you for all of your inputs!

 

Mine (2005 XJ8-L) exhibits similar behavior. I have made an appointment for next week to reconfigure the transmission control module (TCM). The dealer indicated it takes about a 1/2 hour. I've attached the TSB. It does state the XJ range so it should include the R.

I'll let you know how it works out