He all happy Jag owners.
I have 04 XJ8 with 89000 in it. When I'm driving up the hill , little hill or even on straight road with the constant speed my RPM gauge in going up and down by about (range)100 RPM's. I can feel the car accelerating a little bit when RPM's go up.

Any body had that problem. Or you guys know what it might be?

The car is running very good. No issues except this one. It does not bother me too much but I don't think that's normal.

Thank You all and enjoy your Jags.

 

My wife's XK does that sometimes we had a throttle sensor replace a few months ago and a reflash of the computer and it seems to be a lot better. Maybe get it checked at a dealer just to make sure. Our Town and Country 2010 does it a lot.

 

That sounds like a failing trans torque converter. They will start to slip & grab, slip & grab causing a slight RPM flair. It will only get worse as time goes on. Sometimes a clearing of the trans adaptions can help the situation, but you usually end up with a torque converter.

Good luck!

 

It all depends on when the problem occurs. On warm-up and for some minutes after, this hunting syndrome is a well known issue, and is normally cured with a tranny software reflash. If it's all the time even when hot, then XJRguy may well be right. IMHO you have the syndrome, not a failure, but only time will tell.

FWIW, I get the same thing as described above, but once warm it disappears. on my recent German holiday trip I noticed it, but once on the autobahn, you can keep it at 90 mph all day without any trouble, (apart from stopping for petrol every so often, of course !!)

 

I'm working only 20 minutes from my house so I'm not taking the car for long trips.
It looks like this problem appears after about 5 minutes of driving and it's getting better after about 10-15 minutes of driving.
It looks like I have this problem when I'm going up the hill. On flat surface I didn't notice that.
I had the transmission flush about 2 weeks ago. But this problem appears before that was done.

Any body know how much I'm looking to spend for trans torque converter?

 

Could be a fuel trim issue. Hook your OBD reader up to your laptop, have a look at the long term fuel trims, then set it to log your short term fuel trims, try to reproduce the symptoms, and see if it fluctuates by a large amount.

 

From your latest description, you have the "normal" hunting issue, and will not need a new torque converter. That's assuming it disappears when fully hot. You say you had a transmission flush, which I assume is the fluid was replaced. Have you had a software reload (reflash), or not ?

I don't know what a torque converter costs exactly, sorry.

 

Fraser, I'm going to have to differ with you on a couple of points. First, I don't consider any of this "hunting" business these transmissions do as normal. For anyone whom really pays attention to their car, it detracts from the enjoyment. Second, our experience has been that some of them exhibit the condition during warm up and not when fully warm, some never feel it on a cold start, but it shows up as it approaches operating temp, and in some, it's just there almost all the time.

Over time we have just learned that the best course of action is to attempt to correct it first by doing the TCM adaption clear and reconfiguration. For some folks, their seat of the pants feel is satisfied with that improvement, others are not; everybody is different. The only true fix will be a torque converter, and of course, that's expensive. If you shop around you can probably find a reman part for $500-$700, a converter from Jaguar is over $1000. Then you have the labor for the trans R&R on top.

Cheers,

 

Have you had a software reload (reflash), or not ?


No I did not.

 

I used the word 'normal' in an ironic sense, in that this issue has been around so long and experienced by so many, that in the famous words of a large IT supplier, "Its not a bug, Sir, it's a feature" seems to describe how dealers and Jaguar themselves seem to treat the problem.

I agree, we shouldn't have to put up with this sort of issue, and yes, it does detract from enjoyment of the car. Why Jaguar cannot sort this thing out properly, I do NOT know !! FWIW, I still get this syndrome on warmup ocasionally, when driving in certain circumstances, but car is perfectly OK when on cruise. Main issue I have currently is slugglishness around 40-50 when on a twisty road. Car is very reluctant to change down unless I really press on the accelerator. There is somethibng amiss, but I can't put my finger on it. No fault codes at all.

Only thing I can say, is that I won't be replacing my torque converter until I really have to, which will be when the car becomes difficult/impossible to drive.

One final question - assuming a new torque converter cures the problem, what stops the hunting from coming back, if it is a premature wear problem ?

 

Well, I understand where you are coming from, and I hate it that some dealer people take that attitude......frustrating.

Also, as with most things in the car business it's not really Jaguar's deal to sort out, that falls on ZF, the maker of the trans. Luckily, they do seem to have it sorted. Problem is, there are numerous cars out there that do or will exhibit the condition at some point. After late 2005 assembly, we don't see too much of it, seems more confined to those built before then. Once the converter is changed I think the risk of a repeat is pretty small, provided the rebuilder is on his game, a new one I know is pretty reliable.

Now, here we have a teaching moment.........
I can see you are one who really DOES pay attention to his car. Lots of people SAY they know what's going on beneath them, but precious few actually do. I think you have detected a function of your transmission that is working exactly as it was designed, you just don't know it. The ZF utilizes a function they call Corner Recognition. During some spirited driving, say, on twisty roads, the TCM picks wheel speeds off the network and monitors them. If it sees one front wheel speed up compared to the other one, it "knows" you are in a turn. At that point it will INHIBIT shifting. It does that so the torque is not removed from the drive wheels during maneuvers. We all know that can lead to tires breaking loose. Now if you push it [the pedal] far enough, it figures "this guy wants to get with it", and will finally force a downshift.

Edit: I should add that this function can kick in if the tires are mismatched or of uneven tread depth. I have seen this happen. Guy puts one new front tire on and suddenly it won't upshift until he almost floors it. Weird.

So, kudos for truly paying attention.

Cheers,