You need to understand that transmissions are not designed for any one style of shifting. That really is why we have a sport mode built into the ZF. It's always a trade off. Here is where the problem is at. When an automatic transmission shifts you have to release the current gear and connect the next gear. There is always a bit of overlap when this happens. Now they have figured out that to get really smooth shifts the engine torque needs to be backed off when the shift occurs. Or you can slow down the speed of the shift but that increases transmision wear. Ideally we want an instant shift to the next gear with no overlap. This is what shift kits mostly do. This increases the harshness of the shift. So even though it feels worse it's much better for the transmission.

The ZF also modulates the hydraulic line pressure which is another variable in shift quality. So the adaptive techniques really focus on this line pressure to try and get the shifts where the current driver wants them.

The 2nd to 1st downshift clunk is because they tried to add some engine braking to the automatic. Most automatic transmissions do not do this.
I like a bit of feel in my shifting so I leave it in "Sport" mode.
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I wasn't meaning that a tranny was designed for any one style of shifting but they are designed not to lurch. You don't see people with every other tranny saying they have a lurch.

On some boxes you can hardly feel changes, on others they're quite easy to feel but none of them lurch in my experience. Except the ZF.

I think they should be honest and say "it lurches, sorry, but that's how it is and the TSB will at best maybe improve it if you're lucky" (or whatever the details actually are cos they don't appear to be what they've so far admitted).

As yet mine only appears to have a mild lurch. If it drifts and becomes bad I dunno what I'll do. Is it just the KAM I'd have to clear? Not that I'd want to as then it loses the other data. Yuck. Can I just clear the TCM? How?

You'll be aware that others (I think STR owners) have complained they can't get the car to red-line, particularly off the line. Another ZF-ism?

 

No. The red line problem is an ECM issue. The 2003's are very bad about short shifting from 1st to 2nd. My 2005 goes to 6100 rpm red line before shifting. That is if I can find a road where I can watch the tach!!!

Same for the other gears but the speed at which it shifts is well above legal limits. So I can only do it on certain roads. I feel Jaguar left a LOT of power in the car that could be exploited if we ever get a decent ECM reprogrammer. This most likely will never happen. The rear gear ratio is also very high at 2.87:1. If it was dropped to say 3.31:1 and a locking differential installed it would really be a monster off the line!!!

No way to just clear the TCM. Have to kill it all. So you are right it starts everything from the beginning again!
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Wouldn't an ECM reflash fix it (for the 2003s)?

You're soooo right about hitting the legal limit!

 

You would think a reflash would help the early 2003/2004 STR but the postings I have read indicate that the fix was only temporary and after a little while of easy driving it reverts back to the short shifting behavior? I don't know enough to understand why??
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I am in no way an expert on any of this, but out of every car I've ever had from a $200 junker to my 300m shifting has never been an issue. Maybe some shift harder or smoother than others and I don't notice anything because the feeling always stays consistent in each car, but this zf transmission feels like garbage to me. Whether the lurch is adaptive programming with a bug or whatever the reason, it's very annoying and nothing has ever fixed it for me. There's a sport button, why can't it simply be an on/off switch for faster shifting? I always leave the car in sport because it shifts a lot smoother than non-sport mode, which is almost unbearable.

 

The problem for me is that the shifting is unpredictable. What happened to the good ‘ol days when the driver adapted to the car, not the other way around. I drive differently depending on my mood and who’s in my car so stop trying to learn what I’m going to do.
Living in the land of rolling stops I've noticed that sometimes it lurches, other times it’s fine. I’ve found a light throttle tip-in seems to help. I think this trans needed another year of software engineering but at this point there is no financial reason for them to develop a fix.

 

I did a 'hard reboot' and its drastically improved shifting both up and down. Non-Sport mode is so smooth and now only when I left off the throttle load at the shift from 1st to 2nd does it give me a mild lurch.

Not sure what thats worth but information is information.

PS great tips here guys, not much info over at the XJ section for this.

 

Is that in the 2004 XJ8? (just making sure)

 

yes it is, sorry i forgot to mention it.

it also gave me the 'set park brake' which i dunno how its supposed to be configured, but i had the brakes and then the park brake button and it disappeared.

much better shifting, and a 50% increase in city mpg. I went from 10.8 to 15.+mpg in the city.

 

Hi StrateLoss, what does that involve?

 

Battery disconnect

(so the KAM loses its kept alive memory lol)

 

My battery was disconnected to replace the ECU and the lurch was there before and after.

 

Just disconnecting the battery is only a partial fix. Did you follow the correct driving procedure to allow the adptive programming to relearn?
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Carry out the adaptation drive cycle road test:
Note: This process must be carried out in normal mode (not sports mode). On a flat road, the transmission fluid temperature must be above 60° C (140° f) and below 100° C (212° f) (vehicle at normal operating temperature will ensure that the transmission fluid temperature is above 60° C (140° f)).
9. Accelerate from rest with light throttle (do not exceed the upper rev limit in appendix 1). 1-2, 2-3, 3-4 shifts must occur with engine speed between the following limits:.
• 3.0L VIN ALL 1800 - 2000 rpm
• 4.2L N/A Prior VIN M96321 1450 - 1600 rpm
• 4.2L N/A From VIN M963221550 - 1700 rpm

10. Continue to accelerate gently to 50 mph (80 km/h) so that transmission shifts into 5th gear.
11. Go into overrun and let the transmission shift down into 4th gear without braking.
12. Brake gently to a standstill and hold footbrake on for at least 15 seconds.
13. This process should be carried out at least five times.

Page 2 of 3 Bulletin Number S307-17

 

After listening to the lurch theory, this got me to thinking. I had a noticable bump from time to time, upon a rolling accelleration - I think Type 2 from the official lurch website. However, the dealer did a transmission service about 6 months ago. To tell you the truth, I haven't felt this in a long time. Could the fluid (accurate levels achieved) and filter change helped somehow? Could the TCM have finally adapted to my driving style? A combination of both? I am not sure...just spouting nonsense I suppose.

 

There's an oddity about the lurch TSB for the STR.

Jag used to say (and still do?):

6 speed transmission adaption process:
This process must be carried out in normal mode (not sports).
The transmission oil temperature must be above 60 deg C (vehicle at normal operating temperature will ensure transmission above is 60 deg C)
Accelerate from rest with light throttle, 1-2, 2-3 and 3-4 shifts must occur with engine speed between 1300-1800 rpm (Supercharged vehicles between 1000-1500 rpm).
Continue to accelerate gently to 50 mph so that transmission shifts into 5th gear.
Brake gently to a standstill and hold footbrake on for at least 15 seconds.
This process should be carried out at least 5 times.

NOTE: The above process must be adhered to rigidly to ensure that the transmission adaptions are completed successfully.

 

i disconnected the negative terminal of the battery,

i touch the positive battery terminal and and lead (still connected) with the negative (disconnected) cable.

then disconnected the positive terminal from the battery.

just the two leads together again , left disconnected for 15minutes

then i reconnected the terminals, started the car, set the brake, let idle for 5 min and followed the procedure mentioned below to the best of my memory.

shifts much smoother now.

try the above steps and it should get better. another way to stop lurching on most all cars is avoid panic stops and any type of stops that shifts the load to the front heavy and then to the rear heavy.

example : brake hard and heavy or whoever it is that you brake coming to a stoplight/sign but try to come to a complete stop about 10 ft before the actuall crosswalk or stopping line.

once almost completely slowed down ease off of the brake and slowly finess the pedal to brake as smooth as possible. this 1-2mph roll within 10ft eases lurching almost to a paint where all you head is a whisp in rpm increase and decrease.

my 2008 civic 'lurchs' on heavy braking. so did my fathers 2000 vdp. my 98 kia , 95 ford van, q45 and even my very first geo metro all lurched downshifting into first at .5mph. its whats automatics do

sorry for the essay but sometimes i can just go on and on and on explaining my thoughts and experiances.


yes i did this the best my memory allowed, this specific procedure IMO leaves to much room for error and sounds more like 'Legal Language' for anyone that knows what that is.

everytime i hard rebooted or reset ecu's i would just start the car, let idle for 5 minutes and take it on a nice easy shifting, light load driving for 3-5 miles with light acceleration to 45 and lights braking.

also with electrical draw kept to a minimum i.e,.. lights, radio, if i wanted my windows open i would open them previous to the motor running

these are my own personal experiances, they can be subject to disagreement and thats fine with me.enlighten us with knowledge

-VIC

 

Interesting because after two weeks of gentle early rush hour commuting and slow, easy stops, the lurch is not as bad. I'll try your suggestion of rolling the last 10 feet.

 

This procedure has been abandonded by ZF. They no longer consider this procedure valid.

 

Reprogramming the ECM, or disconnecting the battery will not erase transmission adaptations. Adaptations are stored in the TCM, not ECM. As far as I know, the dealer software is the only thing out there that can reset trans adaptations, reprogram the TCM and perform the adaptation procedure. Updated adaptation procedure from Jag is done with the laptop. And that I just mentioned cures it......for good.