For the first three or four miles each day, when the car is cold the RPM's (and to a lesser extent speed) wavers about 200 rpm, this can be seen in the tach. As I try to maintain a constant speed (usually around 50 mph) the tach will waver up and down about 200 rpms while under load. This doesn't change the cars speed much but I can hear it and feel it. After the car warms it runs beautifully. I have no codes or a CEL. At least on my simple Foxwell code reader. The air filter is new, the plugs and fuel filter I assume are original (32K miles). Morning temps have been around 70*f. What can this be? I could guess a few things but they would just be guesses. So I ask you gentlemen and ladies, where do I go from here? Thank you in advance.

 

This is a well known issue. It's a transmission programming quirk that can sometimes be solved by reflashing the software. I don't have the TSB handy, possibly someone else can post it for you.

 

Wow, I should have searched for trans. issue. But that never occurred to me. Thanks Mikey.

 

I was told by an ex-Jaguar technician who was around at the time, that this was a clever wheeze to warm the transmission oil quicker by switching the torque converter lock-up on and off quickly until the fluid was warm. I had this syndrome the whole time I had my previous X350 and it was never cured despite a couple of TCM reflashes. In the end I just did a work-round by putting the car into 5 or even 4 for a while.

It just shows that clever wheezes are sometimes not so clever. I suppose this action saved an egg-cup full of petrol every time the car was driven from cold. The cure apparently was to change the torque converter. I queried this with the technician and was told to cure the fault the friction plates were re-profiled on later cars so the action still occurred but was no longer noticeable by the driver. Whether I have been told a load of bullsh*t, I don't know, but what I do know is my current X358 Sovereign doesn't do it.

 

Thank you Fraser. this is good to know. I guess as long as it doesn't worsen and was designed to do this, I won't worry about it. It isn't very noticeable and only lasts about three minutes. I guess I can live with that once a day. Otherwise I love the car. I got rid of the 14 year old maypops on the back and replaced them with Continental ExtremeContact DWS06's. I'm very happy with those, they made the car even quieter than it was!
Thanks again.

 

Interesting Fraser, I hadn't heard the later plates were reprofiled. I wonder how much later they were fixed, if ever. I have never noticed anything of the sort happening on my 04 x350, but I do have it happen in my 06 x100 when at steady speed on certain roads. Interesting enough, I didn't notice the surging prior to me doing a partial transmission fluid flush with Mercon SP, but I noticed it directly after. It could have been happening before and I just wasn't aware. The partial trans flush cured much of the hard downshifting which was occuring, but may have added the surging. No TCM reflash was performed.