My wife's '04 XJ8's transmission started acting up with some hard shifts and then a transmission fault message. We've only had the car a year and it only has 55,000 miles and is a great car. So I took it to the dealer where we bought it, I bought a warranty with the car, and on to the trans shop. After looking at it the trans shop said something about the clutch packs for 4th to 5th gear were bad and their in the process of putting a rebuilt into it.
I've searched the form and haven't seen this problem. Is this unusual because it seems like this trans is pretty bullet proof. I'll know more after they finish and I question the tech. Sure glad I got the warranty.

 

i used to have a xj8 that bought new in 2000, transmission went kaput at 60k

 

Very unusual for that mileage with that gearbox. Most times a TCM reflash and fluid/filter change sorts it out.

 

I would have gotten a second opinion.

 

At least, right or wrong, it's not out of your wallet!

John

 

ldol, you had a different trans. The ZF 6hp26 in the X350's 2003.5 and later seems to be pretty bulet proof and like Fraser said a reflash and fluid change correct any problems that do come up.

 

Fluid was changed 10,000 miles ago.

 

Got the car back the other day, new trans, rebuilt, shop said when they pulled the pan there was a lot of metal. The tech said that an oil passage was blocked and that caused the clutches to go away. Just bad luck I guess.

 

I think you are right -you have been unlucky but on the positive you had a warranty!

 

I have an 04' XJ8 with 96,000 miles on it. I had a transmission leak, but I noticed the problem right away and fixed the leaks in the line, the pan, and got new fluid (all done at certified Jag mechanic). The car functions fine, but I do have a problem when I do rapid accelerations on the freeway. If i'm drving at 65 mph and I want to accelerate rapidly, the transmission downshifts as normal but then it wont shift up to the higher gear at all! It doesnt seem to catch that higher gear and my engine is just reving until I release the gas pedal and it finally selects the higher gear but with an unpleasant jerk. No engine lights or faults appear on the car. Even if I plug in the diagnostic, no codes even appear. I'm not sure what is causing this. Please, can anyone tell me what I can do to fix this problem? How can I do a transmission reflash? Should I be worried that my transmission will fail soon? Lately, I've been driving normal and avoiding high speed bursts.

 

Jagman, that doesn't sound good..at all. If the fluid level is still good (because that is a typical symptom of low fluid) then it could be the torque converter. I'm no expert, but get the level checked again (or do it yourself, its relatively easy if you can get the car level and yourself under it)

 

ihad these same symptoms in my mark viii just before it quit all the forward gears, i had to drive home in reverse

 

I checked the level again and it's perfect and full. There are no leaks at all and everything is solid. However, the problem still persists if I try to accelerate rapidly when I'm already at a high rate of speed. If I drive normal and if I don't accelerate too quickly, the car shifts fine. If it was the torque converter wouldnt the fault sensors pick something up? How much would something like that cost me? Should I try a TCM reflash before taking other actions?

Thank you

 

Are you checking the level by putting the car on a lift, running it up to 40degC trans fluid temp and pulling the plug on the side to check it? If not, then you may have th ewrong fluid level. You may also have the wrong fluid, be sure the shop used the correct ZF Lifeguard6 fluid or all bets are off in solving the problem. The problem you are having should be generating a code that the Dealer can read, I would take it in before doing anything other than a fluid level check. If I had to guess, the slow upshifts could be low internal oil pressure or a shift solenoid problem on the Mechatronics unit.

 

Ok my advice is have them to clear the EEPROM adaptations from the TCM MODULE..The mileage is not high enough to cause issues like this meritting a tranny service.Some early x350 module had torque converter issues.The symptoms were the tacometer would surge about 45-55mph instead of turning maybe 1500-1600rpms it would jump to 3200-3600rpms.The zf6 is really a great transmission...lighter then the zf5,and has less moving parts. Also it would help to ask them for the P-CODE for the transmission.Present it to the forum for further input.

 

Yes, I did exactly all that and I went to check to see if the proper fluid was used and proper methods. All checked out fine, so my next step is to call the dealer and see what codes pop up (if any) and get the TCM reflashed. I'll see if that does the trick. It's funny because my Porsche Boxster started doing the same thing from 4th to 5th gear. I replaced the transmission pan myself and got the correct fluid to pump into the system at the right temp. The Porsche has been shifting perfect after that. I hope the Jag problem can be solved soon.

 

Hi JagMan,
Just wondering if you rectified the problem with your transmission. I have the same car (2004 VDP), with the EXACT same problem, but no leaks, and fluid is full. I have owned the car for 6 months, now at 105,000 miles, and no other problems. Trans started acting this way about a week ago. Any info or pointers would be greatly appreciated.

 

I had that problem when under factory warranty.
They re-flashed it and has been good since.

When someone has an after market warranty they are a good candidate for a re-man.

 

I still think there is a fluid, or a level problem. OR a mix of old and new fluid. Don't forget you don't get all the old fluid out with just a pan drain.

These transmissions are EXTREMELY sensitive to fluid variations. The trans will exibit symptoms with over / under fill conditions of less than 1/2 quart.
Yes a glass of transmission fluid can be the difference between a perfectly shifting trans and one that feels like its about to fall apart.

The usual symptoms with a zf6hp26 experiencing a low fluid condition, are rough shifts and slipping / jerking in low gears, especially when the trans is cold. It's most pronounced in bumper to bumper traffic type situations, I've had cars come in that feel almost like someone who doesn't really know what they are doing with a manual transmission is driving. Once they warm up they seem to shift OK.

What you describe to me though, the lack of an upshift until you release the pedal (Just how far up the rpm will it hold the gear?) is almost indicative of an overfill condition. Seems like someone rushed to fill it and didn't wait for the trans to warm up properly, pumped too much fluid in, and capped it. Too much trans pressure leads to an almost "hydrolocking" of the drums in the transmission. Releasing the throttle, and therefore lowering the pressure in the transmission momentarily initiates the shift.

Don't forget that the torque converter transfers all the power to the engine via hydraulic pressure. There is no mechanical link between the crankshaft and the transmission input shaft on an automatic transmission. Aka spinning the fluid almost like a centrifuge, with two fan shaped drums.

So before you go any further.

Just HOW long will it hold a gear? Indefinitely? Till Redline? Or just higher in the RPM's than you expected it to shift? Is the trans in sport or regular mode.

Next, can you engage each and every gear distinctly using the J-Gate shifter?


Let me know and we will go from there.

Take care,

George

 

George,
Thanks for the reply.
I will have to drive again to verify the symptoms, but from memory (questionable), getting on frwy onramp, hard accel for traffic, trans shifted down to 3rd(?) and when merged, foot lessened on gas pedal at about 70 mph. Car stayed in 3rd, rev's at about 3500. Foot completely off the gas, revs stayed at 3500, decreasing with speed. Got off frwy, and after a stop, car was in 1st, and shifted normally (was in sport mode). Went thru J-gate shifts on surface streets, speed limit 50 mph, and shifted normally. have not had it on frwy since, but trans shifts are normal, never a harsh shift, no flare-up while shifting, all seems normal. I will test again, and put it through all modes (J-gate, sport, spirited, etc.) and post findings.
Thanks again.