Hello again,

I just bought XJ8 3.2 from 1998 and on my way noticed, that while NOT in sport mode, the car is very hesitant to down shift. Even when at relatively low RPM, around 2000 or even below, for down shift I need to press the pedal nearly 2/3 before something happens. Also when going around 100km/h and pressing the pedal to the metal, car down shift only to 4th gear (not sure if it is 4th of 3rd, but revs go to around 3000 so it should be 4th, but it does not matter) but in sport mode it down shift to even lower gear. Also if I press the pedal to some length, it can take around 2 seconds, before the car decide to down shift. I understand, that sport mode changes map of shifting points, but even kick down? Anyone know the exact speeds, at which kick down occur to which gear? For example at kick down it down shifts to 2nd gear up to 85km/h or something like that. It seems weird to me, that when in normal mode, the kick down and down shifts would be so bad. I have driven quite a lot of cars with automatic (some really bad), but this is really terrible. On normal mode it is virtually impossible to control down shifts with gas pedal.
Thanks for your answers. I couldn't find this on forum so I started a new thread.

 

The car learns the driving style of the owner to some extent, particularly shift points. It may be possible that the transmission fluid is low, but give it a little time.

 

. . . and there is extensive discussion on removing the slack from the accelerator cable. Most who have explored this issue have ended up removing an eight to a quarter inch of slop in the cable connection. Sound like that is the place you need to start.

 

According to service manual, while the transmission have 6 different maps, it is not adaptive gearbox, so there should not be an issue.
Fluid should have been changed recently (I even have paper from service about it, among other stuff) and in sport mode, it works absolutely fine.
But yes, I will give it some time and see what happens. : -)


Well, that sounds rather brutal to me. : -) This is definitely later option.

What puzzles me, that it really works superbly in sport mode. So maybe it actually works as it should even in normal mode. That is why I am looking for information about those shifting points. Maybe I am just used to something different. (If you floor it at, let's say 100kph, in normal mode, does it kick down to the same gear as in sport mode?)
One more thing. On my way car suddenly decided, to down shift, out of nowhere, at around 80kph, and hold the revs at 3000 rpm. Lifting the gas, shifting in J-gate to 4rd, nothing had any effect on the revs and they stayed like that for around 15 seconds. Any ideas? Bad connection possibly? It is hard to say of course, what is the problem, but maybe someone has encountered something similar.

 

If i had a problem with the gearbox i would check oil level make sure its good and disconnect the battery positive to neg and hold it for a while so power is off the car for sure. And reconnect and then go for a good drive make sure you got the radio code when lost current it will ask of the code sometimes you can find it in the manual people write it in there.

 

Yes, but right now I am still not sure, if I do have a problem. : -) That's why I am asking about kick down and gear changes speed. Maybe it really is the way it should be.

 

Anyone?

 

Sounds normal to me. But I believe the box does adopt to your driving style. I run mine in 4th around town (not drive to preclude tc lockup). Even so, the kick down is slow;kicks down much faster in sport mode, as it should. It has five gears with shift points mapped to mode and driving style.

 

Thanks for reply. But I am not sure, that 5hp24 in jaguar is adaptable. According to literature (service manuals and internet), it has only fixed maps for certain conditions. Later variations do have ability to adapt. But even if it is adaptable, the biggest question I have right now is, if kick down should work the same way, no matter if it is in sport mode or normal. In my car, at say 60mph, normal mode kick down only to 3000rpm (don't know which gear) and in sport mode one speed lower (4500rpm). If that is normal, that kick down is not giving the best acceleration on normal mode, than it is probably fine. But it seems odd to me.
Btw, mine is running on 5th at 30mph (maybe even at lower speeds), which seem quite low to me. But no problem there, just it doesn't down shift as I would like on normal mode.

 

Are you sure you are in5th at 30? Have you manually shifted to 4th and seen the change in revs? That does seem low.

 

Several people have given you good advice, and instead of trying to find out shift points, you should act on their advice. The easiest one for you to check is the throttle cable, they do go very slack. My transmission is razor sharp because I have 100% WOT (Wide Open Throttle) from adjusting the slack out of it. It responds instantly to any change in my foot's position, and shift down is quick. Put it in sport, and you have to keep your wits about you because that cats taking off.

Here is the link to tell you what you need to do to the throttle, it's on the XKR forum, but it's the same engine as the XJ8: https://www.jaguarforums.com/forum/x...d-38663/page3/

 

Yes, I am positive. I tried to move the the lever to 4th and it did down shift. At 32mph it is in 5th for sure. But probably at lower speeds too. On normal mode the whole gear box is behaving like the kick down cable is loose. But on sport, it shifts perfectly, but keeps the rev little higher than I would like for normal drive. Which is of course why is it called sport mode. : -) But I am telling myself, that if the cable was really loose, than sport mode would not work well too. And since the whole car is in mint condition, I am first trying to find out, if that kick down behaviour is normal or not. (Again, if kick down at normal mode down shift to the same gear as kick down at sport mode.)

 

I left the car at the other side of the town (till the paperwork is done) so I am first trying to find as much info as I can, because I am unable to get there on daily basis. Tomorrow I am going to try the ideas mentioned here. And I am really glad for all the info. Don't want to be viewed as ungrateful for all the info here. : -) But I was really looking for info, if the behaviour is normal or not. And it seems, that there is some problem.

 

Btw. another reason why I am still a little doubtful about the cable is that the engine revs, in normal mode, to 6400 (sport 6700 or something like that) maybe slightly lower (6300 min). If the cable was loose, it would probably up shift earlier, wouldn't it?

 

The throttle cable has absolutely nothing to do with shifting other than to define the TCM's use of shift strategies. There is no transmission kick down cable.

Folks have reported that slack in the throttle cable only produced 70% WOT on the OBII port info. Therefore . . . you are not invoking a kick down request to the TCM. The fact that it works better in SPORT only says the down shift requirements in NORMAL are not met.

Adjust your cable . . . adjust it!

 

Well, that sounds reasonable. : -) I did not check how exactly this transmission work with kick down and so on. Well, I'll see tomorrow.