My 2004 XK8 with 47K miles seems to have somewhat harsh 1-2 shifts. All the other up and down shifts are very smooth. I'm not sure if this is this is normal or not......since my frame of reference is my Nissan Murano with a CV tranny.

I found this TSB http://www.jagrepair.com/images/TSB/...S307-17am2.pdf that talks to this issue. Apparently it requires a dealer to reflash the TCM and ECM followed by a driving new adapation cycle.

I'm wondering if anyone else has had this problem and success with the TSB solution

 

Is it a harsh up shift or downshift? A sort of splat into first when coming gently to a stop is a common problem.

For that one, the reflash is reported to be a mixed bag whether it helps.

 

Upshift only. Butter smooth going down

 

[QUOTE=gwagner;664895]My 2004 XK8 with 47K miles seems to have somewhat harsh 1-2 shifts. All the other up and down shifts are very smooth. I'm not sure if this is this is normal or not......since my frame of reference is my Nissan Murano with a CV tranny.

I found this TSB http://www.jagrepair.com/images/TSB/...S307-17am2.pdf that talks to this issue. Apparently it requires a dealer to reflash the TCM and ECM followed by a driving new adapation cycle.

I'm wondering if anyone else has had this problem and success with the TSB solution[/QUOTE

A CV is a horrid comparison. CVs don't have gears like a regular automatic, more like pulleys and belts. Compare it to a another performance 6 speed and see what you think. I should point out that twin clutch automatics are often smoother too so don't use an Audi or a Porsche as a base line. Now if you really want harsh, try an R8 single clutch automatic, that puppy will give you whiplash. My XKR is in line with other performance cars I've used, the first two gears under load are harsh because that is where the torque is highest.

CVs are cool but they don't take to a lot of power well which is a shame because they are incredibly smooth if done right. The Murano's big brother (the FX, I've got one with a Supercharger) didn't get the CV.

 

When I first purchased my 2004 XK8 it had 63k miles on it and i had the same harsh up shift from 1-2, all other shifts were completely fine. There have not been many people reporting this issue on the forum so there was not much to go on, and I started searching the TSB's too. I tried the hard reset of the car as mentioned often on this site, made no difference. I think I read somewhere subsequently that the hard reset does nothing for the TCU. So I went to my local Jaguar dealer with a very similar TSB and they ended up reflashing the TCU,and this resolved the issue. It is interesting that after I had this resolved, for a long time I continued to brace myself for the harsh shift even though it was gone. BTW, prior to having the reflashing, I had them replace the transmission fluid and pan/filter which made no difference, but I do recommend it for peace of mind.

 

@Steve: Thanks, that sounds exactly like my situation. I too, was surprised to see little discussion of this issue on the forum given that there is a TSB on it.

Do you recall what your dealer charged for the reflash and tranny drain and refill?

 

I'm sure it wasn't as 'crystal clear' since the TSB is for the s-type, and we members knowing the transmissions were identical, we deduced similar TCM reflashes would benefit us. There is actually many many references to getting a TCM reflash, or simply just clearing the adaptations w/o any software updates or reflash. The drive cycle following the clearing is very important, however, to teaching the TCM to shift properly.

 

The TCU reflash was about 240 as I recall, and without a doubt is what resolved my harsh up shift.

BTW, for the record, It was done after I had the fluid and pan/filter replaced. I am almost embarrassed to say that I paid $1200, which also included a quart of the magic bark eliminator elixir which I was also dealing with at the time.

 

Great point Matt about the drive cycle being so important. I had provided my dealer with this TSB, but they reflashed the TCU instead. What they told me was that in discussion with other techs, they believed the results of a reflash were more reliable than going thru the painstaking procedure outlined in the TSB I provided (clearing the adaptations and resetting them as described). I don't really know how factual that is, or what is better. At least it worked for me . Anyhow, I think this TSB is actually specific to this issue and this car. Good luck.

 

@Steve: Thanks!! great info

 

Interesting follow up on this: The Jag basically is my wife's car who lets me drive it on the weekends. While I was aware of the shifting issue, I never mentioned it to my wife........never expecting her to notice it anyway.

So....last weekend I was driving the Jag with my wife as passenger and noticed that the harsh up shift problem was pretty much gone. I casually mentioned something about this to her and her reply was: "oh yeah, I noticed that it was a little rough on take off so I refilled it with premium gas instead of the mid grade you told me to use"

I guess I'm not too old to learn something
1) Don't underestimate the wife
2) Somehow the premium gas affected the ECM/TCM adaptations to smooth out the shifts

I'm still a little skeptical of this being the cure. Is this possible?

 

Play it safe, go with #1.

You can always go with, "If your wife said it, it has to be true."

I don't claim any expertise on this subject, but I do know that these Jags act in truly peculiar ways. It wouldn't surprise me a bit if poor or low octane gas made one of these Jags shift improperly.

I know that I had a Mitsubishi which had what they called "fuzzy logic" for the shifting of the transmission, and I think that our Jags have something similar, where they adapt the shifting to the pattern of the driver. Having two different people driving a car with different patterns may also cause some sort of unexpected reaction.

I have a Dodge minivan and I tow a fishing boat with it. Obviously, it shifts a lot differently when I am towing the boat. I have noticed that it will also have a different shifting pattern for a couple of days after I have towed my boat.

I am going to suspect that your wife drives this Jag more mildly than you do, and your different driving pattern (more depression of the gas pedal) might also have something to do with the shifting.