2006XJ8 Vanden Plas with 51 K miles on it. Bought the car new, never had an issue. We live in sunny and hot AZ, so it has never seen snow or inclement weather...the car started developing a Jerking issue when shifting into D (when cold), same jerking when coming to a stop... It almost felt like the transmission was out of fluid in the morning. First symptoms occurred last March, when the night temp's were still in the 40's, the car would shift perfectly at normal operating temp, but jerk in the morning until operating temp is achieved. I changed the Fluid, Filter/Pan etc etc. Old fluid was clean with no sign of metal shavings...summer came in and all the symptoms went away. Shifted perfectly at any time...Well, we are back in the winter here and the same symptoms are back. In the morning, the tranny Jerks 1 or 2 times when going into 1st, same jerking when coming to a stop - then everything settles back to normal when the temp is normal or after about 20 min of idling...Driving during the day @70F is all good - no issues. I am a bit stumped at this point. Should I send it out for a Transmission Software Update? Should I reset the adaptations? Any input on this would be greatly appreciated!

 

Hi cartopics,

Hopefully one of our members has had the same symptoms and has found the resolution.

I can think of a few questions:

1. Have you scanned the car for any stored Diagnostic Trouble Codes (DTCs)? The basic Powertrain (P) codes can be read by many standard OBDII scanners such as those used by most local auto parts stores. To read any of the proprietary Jaguar codes (including the U or Network codes) requires a system with dealer-level capabilities.

2. When you changed the fluid and pan/filter, did you set the fluid level per the manual instructions and at the specified temperature? Have you checked the fluid level recenlty?

3. Did you replace the cylindrical plastic sleeve around the transmission electrical connector? It is a known leak point, and either low fluid or contamination of the electrical connector could cause your symptoms.

4. Smooth gearshifts rely on communication between the Transmission Control Module (TCM), Engine Control Module (ECM) and other modules, so corrosion on electrical connectors or ground points can contribute to rough gearshifts.

Since your symptoms seem to be temperature dependent, the first thing I would do is check the fluid level and for any signs of leaks, especially at the electrical connector.

Cheers,

Don

 

Don,
I do have a SDD setup and I can scan, but the transmission never set any codes - I will double check. The case is bone dry and I don't see any leaks at the Sleeve. Fluid is at the correct level.

 

In the event of a catastrophic failure - I am not ruling that out and preparing myself for the worst case scenario. Does anyone know if swapping transmissions requires any coding? Or is it a plug-and-play? (Obviously ZF 5HP24 to ZF 5HP24 from another XJ8).

Thanks.

 

If your XJ8 is a 2006 it should have a ZF 6HP26 six-speed. What fluid did you use when you changed the pan/filter? Did you flush the old fluid out of the torque converter or just replace what drained from the pan?

How are you measuring the temperature of the fluid while you check the level?

Sorry for all the questions, just trying to think of all the possibilities.

 

I followed the "Sticky" in the forum for the Transmission fluid change. Used Pentosin ATF1. I let the transmission drain for about 6 hours, about 5.5L went back in. Used the Infrared Temperature Meter to measure optimal temp to add fluid. Verified Fluid level 1 day after and 2 days after at 35C and 45C. All good..I was sure they have the 5SPD? (SAJWA82B66SH01714). Now that I am getting more paranoid, I am also sensing a slight hesitation in the idling when cold, a hesitation that may coincide with the "bucking" when in gear...I also tried shifting manually - starting in 2nd in switching manually, this seems to have ameliorated the Hard Bucking, however still noticeable when coming to a stop...

 

The more I am listening to this car, the more I believe there is an actual engine misfire when cold that is throwing the Transmission into a "Jerk" when shifting...The misfire is there in the morning (when cold) and not in gear...I have done the plugs last night, the original ones looked good - no signs of issues. Since there are no codes thrown, I am running a bit in the dark. Is it possible that a misfire in the engine will throw the wrong signals to the transmission?

 

Our S-Type did that. It had two bad coil packs.

 

Hmm...Possible. It is sunny and 75F now, you could swear this car just rolled off the lot. No misfire, no jerking no issues...Is there anything else that possibly adjusts Air/Fuel/Electrical while under cold weather? Maybe a sensor is off?

 

MAF could be an issue as well. Coil packs can cause a rough shift, but it would likely constantly buck at 50 mph.

 

True, unfortunately I don't have any codes...So I am running in the dark, I could throw money at it (MAF/Coils) and hope that I nail it or just wait and hope that it will set a code. Would the MAF act funny when cold and then level out? Wouldn't it just run rough/oscillate continuously?

 

Temperature can play a huge part on how sensors work as they are wearing out. When a couple coils went out on the S-Type, the failure was so intermittent that I never had a code. They can either be tested or you can do what I did and replace them all. I used OEM and replaced the spark plugs while I was at it.

 

Did you find a good price for the Coils? I know from BMW's that they don't like just any coils...

 

I used OEM ones, but I bought them from a liquidator that bought out the supplies from a Jaguar dealer that closed, so 8 coils only cost me $300. I wouldn't recommend going aftermarket.

 

It was explained to me around 2011, (car bought in 2010), that very gradual wear in the box can result in pressure changes in the valving, and a reflash of the TCM software can reset the system to recognise the values present rather than those set at tranny build time. If nothing is done the pressures continue to change until eventually the pressure values will be detected as out-of-range and a fault display and code will appear.

This wear doesn't mean the transmission is worn out, BTW

Yeah, I know; what was wrong with the old Borg Warners ?

 

A quick update for all that may be interested...I had the car cool off overnight and at 4 am I had it hooked up to my LAUNCHX431 live data (the JLR SDD didn't find anything). I had it running for about 45 minutes collecting live data and displaying all 8 cylinders misfire sequence. At exactly, 50 minutes in - cylinder 2 misfired 11 times and then went back to normal. No codes found with Autel DS708, JLR SDD or Launch X431, but the LAUNCH has the live data. Purchased a coil at a local European store and so far - no more issues. No transmission bucking or jerking. I'll keep my fingers crossed - but this is the craziest thing. The local Jaguar of North Scottsdale diagnosed a bad valve body on the transmission and another shop - a rebuild of the transmission. So far it cost me a coil and a set of plugs + Transmission fluid change. I will keep you guys updated!

 

cartopics,

Congratulations on tracking this one down, and thank you for reporting back so we know how you resolved the issue. Thanks also to Torrid for suggesting a coil as a possible suspect.

Unfortunately, as far as I was able to determine, the OE Denso coils are no longer available. But for the benefit of other members who may find your thread due to similar symptoms, I've had good performance so far from the Airtex 5C1420 coils, which are marked FoMoCo, indicating Ford is supplying them for their own vehicles now (Airtex is an OEM to Ford, Chrysler, GM, Toyota and others). RockAuto sells the 5C1420 coils for less than $40.00 each.

Cheers,

Don

 

Well, I must say that all symptoms have completely disappeared. The vehicle runs amazing! Thank you Torrid and Don for the input and a "thank you" to a local diagnostic shop that kindly loaned me their expertise and tools!!! I am not sure if I can mention names / or websites, but they were the first ones to suggest that I may have a misfire that is causing my headache. Also, I must say that the Launch Diagun (X431) has been the most amazing diagnostic scanner I played with so far. The Live Data options are amazing. On a last note - the coil I purchased is working excellent. Although not OEM, it was the only thing available on a Sunday morning. The COil is a IMPORT DIRECT brand available at O'reilly Auto Parts, part number 23-0112 (AJ810445) and the cost is $46.00. And lastly - I am disappointed at the "local" North Scottsdale Jaguar Dealership that has diagnosed the car with a bad valve body in the transmission. They were 100% certain, according to their Service Manager. This is proof that it is always good to get a 2nd or 3rd opinion on just about everything!

Thank you all.

 

Glad to help out. I was sure I had a bad transmission when when it happened to me too. I took a gamble replacing all of the coils. I replaced all the plugs first with no change in the issue. After seeing it happen myself and also now your experience I'll know where to look when it happens to me again.

I'll note that Airtex part info down. When it happens I may replace the whole set on this car too for that price.

 

Are you thinking of the old BW66 used in the series I, II, III? Those were little workhorses but a little too small for the vehicles. As I understand it, they were originally used in the early 60's Buick "Specials".

Those cars were much smaller. Jaguar bought them out and used them along with the GM 400 which I think had fewer complaints than the BW66?

Maybe I imagined all this....