I am presently experiencing a shifting issue with my XK8 and wanted to see if others had experienced the same issue. On the first drive of the day I will experience a delay shift to 2nd gear. However, after the first shift the trans shifts smoothly and on time every time and will respond without hesitation. I had the transmission rebuilt and the valve body replaced and the same thing. I looked into voltage, trans and TCM connections with no success. I am about to have the TCM tested and/or re-flashed but wanted to see what others have done. I am seeing several posts with the same issues with no solution .

 

Bump!

 

I was recently asked do we really have a problem with the ZF transmissions after I posted this thread. See the attached links

Link Another Transmission Issue - Jaguar Forums - Jaguar Enthusiasts Forum

Link 2003 S Type R Transmission Failing - Jaguar Forums - Jaguar Enthusiasts Forum

Link Transmission lurching after 100k miles, 2000 XK8 - Jaguar Forums - Jaguar Enthusiasts Forum

I know of another post from Matt XK8 that I am unable to find and of course my transmission.

How many others that have not posted or had a problem with shifting and fixed it? If you fixed it what did you do?

 

Torque converter? I just posted the same response to another question: does the first bullet sound like your issue? I had this in another vehicle. It sounded like a huge fan whirring until I shifted into second. After that it would shift fine for long periods and then once in a while either when cold or when I would park for 5-10 min's with engine running, it would happen again.

Abnormal Transmission Engagement
• A transmission that fails to shift into gear quickly and efficiently,especially when shifted from park to drive, is normally the result of a bad or dysfunctional torque converter. A lack of torque converter pumping strength can result in slow, delayed transmission engagement.
Transmission Surging
• Transmission surging is a condition where a vehicle's transmission alternates between periods of smooth, steady transmission function and brief, erratic periods of transmission jumping or lurching. This type of transmission function is normally the result of a torque converter that is losing its ability to deliver smooth, constant hydraulic fluid pumping action.
Slippage
• This is another common TC problem, and causes your car to resist acceleration while the engine continues to rev. The most common cause is low or overheated transmission fluid.

 

This car is on its 3rd torque converter with the same issue, rebuilt the trans same issue and replaced the valve body the same issue. What I do not understand is that I can put the shifter in manual “4” and it so far runs great. What is the difference between the two selection “D” or “4” it is the TCM or the ECU? Or something else!

 

Gus,
Does engaging 'Sport' mode make a difference ?

 

I have not move to that step yet I want to be sure that the shifting is not an issue with it in "4" first.

 

Fair enough - but getting a difference in 'S' maybe points to an electronic rather than a mechanical problem ?

 

Thanks! I have been playing with this for the past 6 to 9 months. The transmission is an area that I know little about and my only association with it is to put it in gear and it is to go if not you take it to the shop. For me that has all changed! I am getting hands on and contacts with Trans repair shops and ZF but wanted to see if others experienced the same issues and to see what they found. It is amazing how much you can learn when you talk about the problem. When this is all over I will have a lot to write about.. Then I will begin to work on the other things I put off for now.

 

I've had the same issue for a month, but thought it was the trans cable not being adjusted. Car will go into D and the car will move forward, but not shift. I noticed that the D would not light up. After a couple of shifts to neutral and back to D, the D would illuminate and all was well. This was only at start-up like you experienced; once going, the problem wouldn't return until next day. The thing that made me think of the cable is if I am in 4 and shift to 3, I can't get back into 4 again. The shifter moves, but maybe not enough to get the rotary position switch back enough. Naturaly, going into D at that point trips a trans error, since the TCM thinks I'm in the 3 position along with the 4-D switch signal. All is well at start up the next time.
I haven't tried to see if there's a difference in sport mode, but I will over the next few days to see if that gives any clues.
It could be that the gear shift lever is moving the trans gear selector far enough to change fluid flow in the trans, but the rotary switch may be wearing out or out of adjustment enough to not always properly signal the TCM. Good luck, and I'll post if anything comes up while I investigate my problem.

 

I thought about the shifter selector being part of the problem but mine was changed and adjusted, they broke the original one in the process of installing the trans. My trans has a problem upshifting from 1st to 2nd in the “D” position on a cold start only. I can put it in the manual position “4” on a cold start and leave it there it shifts perfectly every time (stop and go without interaction from me) for the past two weeks. I plan to put it in “D” with “S” mode turned on to see what is taking place.

From what I understand this transmission is not totally mechanically it is dependent on signals from the engine controls to make the transmission control module (TCM) to operate the transmission. So my take on this is that the trans is totally dependent on the TCM to tell it what to do (in manual “4” and auto “D” all functions) and the TCM is dependent on the ECM and all the other stuff that sends a signal to it. And the TCM & ECM are dependent on good programming (flashing) from Jaguar.

My plan is to have the TCM tested on the bench to see that all functions of the module are correct then to get it reflashed.

 

My thoughts too. The reason I was thinking rotary switch is that it seems like my trans engages 1st gear mechanically in D, but won't shift further because the TCM is getting input from the rotary switch that the trans is in neutral. That's why the D doesn't light up. Once I fiddle with the shift lever and the D lights up, then the TCM is getting the signal that the trans is in drive and so shifts normally. Too bad there's no way to substitute a known good switch to see if it helps. (Unless someone out there has an extra they're willing to loan out.) Maybe Jaguar dealer diagnostics can read the signal or test the integrety of the circuits involved?

 

After verifying fluid level, pull the TCM and Tranny harness electrical connectors and spray them with electronics cleaner and reseat carefully. Get the Rotary switch setting tool JD 161 (SPX Jaguar Tools) and set up the switch correctly. Check the shift cable for hanging up in the sheath. If none of this works, get the TCM reflashed and checked for problems. None of these problems sound mechanical to me, I don't think it's the TC or the valve body. I think its either the cable or the harness.

 

The Shifter selector switch was checked replaced and adjusted as the TSB suggested. As for the harness it was replaced from the valve body to the outside of the trans. I checked the cannon plug from the trans to the TCM and cleaned all the connectors No Joy! I have not traced all the leads to the TCM however I did pulled and tugged on the leads at both connectors. NO JOY!

 

Gus, I certainly don't have any level of expertise here, but I have experienced the same thing with other cars that I have owned. (not with my Jag, as I live in a small subdivision with 25 mph speed limit and go pretty slowly for a while until I can speed up) With my other vehicles, they seemed to hold to a lower gear longer when the weather was cold and would not shift up as quickly as in the summer. There was also a bit of a bump when they finally shifted that was not there in the summer.

I always assumed that it was some sort of method to try to get the engine to run up to more RPM to help it heat up sooner. I may be totally off base here, and this may have nothing to do with your situation, but it is similar to what I have experienced. Good luck.

 

This has been going on since last summer when I was in OC Md with temps well over 75° and now with temps under 50°. I thought of the temperature, humidity, weather and it does not change the situation I even thought of driving habits with NO JOY!

 

Still okay in 4 but not in D? Only difference betwen the two positions is the "D to 4" switch in the shifter console that tells the TCM to not go into 5th gear when 4 is selected.

 

That is what I thought and that is why I do not get it. Still on my quest to find answers. I will keep you posted unless someone has the answer and posts it.